Page 1 Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Agilent Technologies...
Page 2 © Agilent Technologies, Inc. 2007-2013 Safety Notices Firmware Version No part of this manual may be reproduced This manual is written for 7890 Series GCs in any form or by any means (including using firmware version B.02.01. C A U T I O N...
Page 3: Table Of Contents
Contents Programming Run Time Programming Using run time events Programming run time events The run table Adding events to the run table Editing events in the run table Deleting run time events Clock Time Programming Using clock time events Programming clock time events Adding events to the clock table Editing clock time events Deleting clock time events...
Page 4 Inlets Using Hydrogen Inlet Overview Carrier Gas Flow Rates About Gas Saver To use gas saver Pre Run and Prep Run The [Prep Run] key Auto Prep Run About Heaters About the Split/Splitless Inlet Septum tightening (S/SL) Standard and high-pressure versions of the S/SL inlet Split/Splitless inlet split mode overview Split/Splitless inlet splitless mode overview The S/SL inlet pulsed split and splitless modes...
Page 5 About the Cool On-Column Inlet Setup modes of the COC inlet Retention gaps COC inlet temperature control Setting COC inlet flows/pressures Setting COC inlet parameters About the PTV Inlet PTV sampling heads Heating the PTV inlet Cooling the PTV inlet PTV inlet split and pulsed split modes PTV inlet splitless and pulsed splitless modes PTV inlet solvent vent mode...
Page 6 Select a column mode Setting the column parameters for constant flow or constant pressure Enter a flow or pressure program (optional) Programming column pressure or flow Backflushing a Column Backflushing when connected to an MSD Backflushing using a capillary flow technology device Nickel Catalyst Tube About the nickel catalyst tube Nickel catalyst gas flows...
Page 7 uECD makeup gas notes uECD temperature programming Setting parameters for the uECD About the NPD New NPD features and changes NPD software requirements NPD flows and general information NPD flow, temperature, and bead recommendations NPD required gas purity Setting parameters for the NPD Selecting an NPD bead type Changing from a ceramic bead to a Blos bead Selecting an NPD jet...
Page 8 Lighting the FPD flame Setting parameters for the FPD Valves About Valves The Valve Box Heating the valves Valve temperature programming Configuring an Aux thermal zone Valve Control The valve drivers The internal valve drivers The external valve drivers Valve Types Configuring a Valve Controlling a Valve From the keyboard...
Page 9 Column Compensation Creating a column compensation profile Making a run using analog output column compensation Making a run using digital output column compensation Plotting a stored column compensation profile Test Plot Auxiliary Devices Auxiliary Devices About Auxiliary Pressure Control About Aux Thermal Zone Control About Cryo Trap Control About Auxiliary Device Contacts About the 24V Auxiliary Device Power Supply...
Page 10 Advanced Operation Manual...
Page 11 Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Programming Run Time Programming Using run time events Programming run time events The run table Adding events to the run table Editing events in the run table Deleting run time events Clock Time Programming...
Page 12: Programming
Programming Run Time Programming Run time programming during a method allows certain setpoints to change automatically during a run as a function of the chromatographic run time. Thus an event that is programmed to occur at 2 minutes will occur 2 minutes after every injection.
Page 13: Programming Run Time Events
Programming • Detector gas flow (on/off), including NPD H fuel gas • Inlet septum purge flow Programming run time events Press [Run Table]. Press [Mode/Type] to see the available run time events. Scroll to the event to be programmed. Press [Enter]. Enter values for the Time: and the other parameter.
Page 14: Editing Events In The Run Table
Programming Editing events in the run table Press [Run Table]. Move the cursor to the event you want to change. To edit the time for an event, move the cursor to the line labeled Time:. Type the desired time and press [Enter]. To edit a setpoint value, scroll to the setpoint line.
Page 15: Clock Time Programming
Programming Clock Time Programming Clock time programming allows certain setpoints to change automatically at a specified time during a 24- hour day. Thus, an event programmed to occur at 14:35 hours will occur at 2:35 in the afternoon. A running analysis or sequence has precedence over any clock table events occurring during this time.
Page 16: Adding Events To The Clock Table
Programming Adding events to the clock table Press [Clock Table]. Press [Mode/Type]. When entries are added, they are automatically ordered chronologically. Select the event type. Set appropriate parameters. Repeat this process until all entries are added. Editing clock time events Press [Clock Table] to view all events programmed.
Page 17: User-Key Programming
Programming User-Key Programming The two User Keys create macros (sets of frequently used keystrokes) and assign them to single keys. A macro is executed when the User Key is pressed. The stored keystrokes may be any keys except [Start], [Prog], [User Key 1], or [User Key 2].
Page 18: Post Run Programming
Programming Post Run Programming This function can be used with both isothermal and programmed methods. Post run is a period that begins at the end of the normal run. The parameters include: • Time—How long is the post run period? •...
Page 19: Flow And Pressure Modules
Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Flow and Pressure Modules About Flow and Pressure Control Maximum operating pressure PIDs Inlet Modules Detector Modules Pressure Control Modules Auxiliary Pressure Controllers Restrictors 1. Using an Aux EPC channel to supply purge gas to a splitter 2.
Page 20: About Flow And Pressure Control
Flow and Pressure Modules About Flow and Pressure Control The GC uses four types of electronic flow or pressure controllers; inlet modules, detector modules, pressure control modules (PCMs), and auxiliary pressure controllers (Aux EPCs). All of these modules mount in the slots at the top rear of the GC.
Page 21: Pids
Flow and Pressure Modules PIDs The behavior of a pressure control module is governed by a set of three constants, called P (proportional), I (integral), and D (differential). Certain gases or special applications (such as QuickSwap, headspace vial pressurization, or splitter and backflush applications) require different PIDs than those provided at the factory.
Page 22: Inlet Modules
Flow and Pressure Modules Inlet Modules These modules are used with specific inlets. They provide a controlled flow or pressure of carrier gas to the inlet and control the septum flow rate. Module locations depend on the type of module and the length of the tubing connecting it to the inlet.
Page 23: Detector Modules
Flow and Pressure Modules Detector Modules These are specific to the detector with which they are supplied, and differ according to the needs of that detector. For example, the FID module must supply controlled amounts of air, hydrogen, and makeup gas. The TCD module supplies the reference and makeup gases, but includes the reference switching valve that is essential to detector operation.
Page 24: Pressure Control Modules
Flow and Pressure Modules Pressure Control Modules The PCM is a general purpose module with two independent control channels, designated 1 and 2. The general name of a PCM module is PCM #, where the # (actually, a letter) identifies the PCM (there can be up to 3 installed). The two channels are not identical.
Page 25 Flow and Pressure Modules pressure mode can be very useful with a gas sampling valve, where it ensures that the sample pressure in the loop remains constant. For channel 1, gas input is via a threaded fitting. Gas output is via a coil of metal tubing with a Swagelok fitting on the end.
Page 26 Flow and Pressure Modules • In slot 5. If there are no PCMs in slots 1 and 2, the name is PCM A. If another PCM is installed in either slot 1 or 2, the PCM in slot 5 takes the name that is not being used (A or B).
Page 27: Auxiliary Pressure Controllers
Flow and Pressure Modules Auxiliary Pressure Controllers The Auxiliary Pressure Controller (Aux epc) is also a general purpose device. It has three independent forward- pressure regulated channels. Channels are designated by numbers 1 through 9 (there can be up to 3 Aux epcs), depending on where the module is installed.
Page 28: Restrictors
Flow and Pressure Modules Restrictors Both PCMs and auxiliary channels are controlled by pressure setpoints. To work properly, there must be adequate flow resistance downstream of the pressure sensor. Each channel provides a frit- type restrictor. Four frits are available. Table 2 Auxiliary channel frits Frit marking...
Page 29 Flow and Pressure Modules When installing or replacing a frit, always use a new O- ring (5180- 4181, 12/pk). Selecting a frit The frits change the control range of the channels. The objective is to find a frit that allows the required range of flows at reasonable source pressures.
Page 30: Examples
Flow and Pressure Modules Examples 1. Using an Aux EPC channel to supply purge gas to a splitter An Aux EPC channel operates only in the forward- pressure mode; it provides a constant pressure at its outlet. It is used to provide gas to some other device, such as a splitter with a makeup gas input.
Page 31 Flow and Pressure Modules Channel 1: Forward-pressure only This is identical to the carrier gas channel for the packed column inlet. Channel 2: Two-way channel If gas is supplied at the threaded connection and delivered by the tubing, this operates the same as channel 1. But the connections can be reversed—requiring some fittings—so that it will maintain the gas supplied to it at a fixed pressure.
Page 32 Flow and Pressure Modules Advanced Operation Manual...
Page 33: Inlets
Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Inlets Using Hydrogen Inlet Overview Carrier Gas Flow Rates About Gas Saver Pre Run and Prep Run Auto Prep Run About Heaters About the Split/Splitless Inlet Split/Splitless inlet split mode overview Split/Splitless inlet splitless mode overview...
Page 34 Inlets Cooling the PTV inlet PTV inlet split and pulsed split modes PTV inlet splitless and pulsed splitless modes PTV inlet solvent vent mode To develop a PTV method that uses large volume injection Multiple injections with the PTV inlet About the Volatiles Interface About the VI split mode About the VI splitless mode...
Page 35: Using Hydrogen
Inlets Using Hydrogen When using hydrogen (H ), as the carrier gas, be aware that WA R N I N G hydrogen (H ) gas can flow into the oven and create an explosion hazard. Therefore, be sure that the supply is off until all connections are made, and ensure that the inlet and detector column fittings are either connected to a column or capped at all times when hydrogen (H...
Page 36: Inlet Overview
Inlets Inlet Overview Table 3 Comparing inlets Sample Sample Comments Inlet Column Mode concentration to column Split/splitless Capillary Split High Very little Pulsed split High Useful with large Very little injections Splitless Useful with large Pulsed splitless injections Multimode Capillary Split High Very little...
Page 37: Carrier Gas Flow Rates
Inlets Carrier Gas Flow Rates The flow rates in Table 4 are recommended for all column temperatures. Table 4 Column size and carrier flow rate Column type Column size Carrier flow rate, mL/min Hydrogen Helium Nitrogen Packed 1/8-inch 1/4-inch Capillary 0.05 mm id 0.10 mm id 0.20 mm id...
Page 38: About Gas Saver
Inlets About Gas Saver Gas saver reduces carrier flow from the split vent after the sample is on the column. It applies to the Split/Splitless and PTV inlets (all modes) and to the split and splitless modes of the Volatiles Interface. It is most useful in split applications.
Page 39: To Use Gas Saver
Inlets To use gas saver Press [Front Inlet] or [Back Inlet]. Turn gas saver On. Set Gas saver flow. It must be at least 15 mL/min greater than the column flow. If in split mode, set Saver time after injection time. In all other modes, set after Purge time.
Page 40: Pre Run And Prep Run
Inlets Pre Run and Prep Run With some inlets and operating modes, certain instrument setpoints are different between runs than during an analysis. To restore the setpoints for injection, you must place the GC into the Pre Run state. You must use the Pre Run state when: •...
Page 41: Auto Prep Run
Inlets Non-Agilent samplers With most automatic injection systems, you do not need to use the [Prep Run] key. If your sampler or automation controller (for example, an integrator or workstation) does not support the [Prep Run] function, you must set the GC to Auto Prep Run.
Page 42: About Heaters
Inlets About Heaters Inlets (and detectors, valve boxes, etc.) are heated. There are six heater connectors on the GC mainframe, located as shown here: Front of GC Near front inlet Near top right corner of front detector board Near top right corner Near back inlet of back detector board Left end of valve bracket...
Page 43 Inlets Table 5 Heater connection locations by module (continued) Module Available heater connection location AUX 7,8,9 None Valve box 5 or 6 or Both Aux heater 1 Aux heater 2 Front FPD uses heater connectors 3 and 5. Back FPD uses heater connectors 4 and 6. FPDs can be configured for one or two heater versions.
Page 44: About The Split/Splitless Inlet
Inlets About the Split/Splitless Inlet This inlet is used for split, splitless, pulsed splitless, or pulsed split analyses. You can choose the operating mode from the inlet parameter list. The split mode is generally used for major component analyses, while the splitless mode is used for trace analyses.
Page 45: Split/Splitless Inlet Split Mode Overview
Inlets To determine the version that you have, press [Front Inlet] or [Back Inlet], scroll to the Pressure line, and press the [Info] key. The display will show the pressure range for the inlet—either 1 to 100 psi (for the standard version) or 1 to 150 psi (for the high- pressure version).
Page 46: Split/Splitless Inlet Splitless Mode Overview
Inlets Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Split/Splitless inlet splitless mode overview In this mode, the split vent valve is closed during the injection and remains so while the sample is vaporized in the liner and transferred to the column.
Page 47: The S/Sl Inlet Pulsed Split And Splitless Modes
Inlets Carrier Supply Split Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap Inlet Weldment FS = Flow Sensor Column PS = Pressure Sensor The S/SL inlet pulsed split and splitless modes The pressure pulse modes increase inlet pressure just before the beginning of a run and return it to the normal value after a specified amount of time.
Page 48: Split/Splitless Inlet Split Mode Minimum Operating Pressures
Inlets You can do column pressure and flow programming when in the pressure pulse mode. However, the pressure pulse will take precedence over the column pressure or flow ramp. Pressure pulse Pressure Flow Pressure or flow program Split/Splitless inlet split mode minimum operating pressures The minimum recommended inlet total flow is 20 mL/minute.
Page 49: Selecting The Correct S/Sl Inlet Liner
Inlets Table 6 Approximate minimum viable inlet pressures for split/splitless inlet in split mode, in psi (kPa) Split vent flow (mL/min) 50–100 100–200 200–400 400–600 Helium and hydrogen carrier gases Split liners - 5183-4647, 19251-60540 2.5 (17.2) 3.5 (24.1 4.5 (31) 6.0 (41.4) Splitless liners - 5062-3587, 5181-8818 4.0 (27.6)
Page 50 Inlets Splitless liner The liner volume must contain the solvent vapor. The liner should be deactivated to minimize sample breakdown during the purge delay. Solvent vapor volume can be reduced by using Pulsed Splitless mode. Use the “Vapor Volume Calculator“ to determine vapor volume requirements. Vapor volume <...
Page 51: Vapor Volume Calculator
Inlets Vapor Volume Calculator Agilent provides a Vapor Volume Calculator to help you determine if a liner is suitable for a method. To use the calculator install the Agilent Instrument utility provided with the GC. The calculator is also provided with the Agilent Instrument Utilities software.
Page 52: Selecting Parameters For The S/Sl Splitless Mode
Inlets If a column in the flow path is not defined Press [Front Inlet] or [Back Inlet]. Set the inlet temperature. Set Total flow into the inlet. It must exceed your intended Septum Purge flow. Measure the split vent flow using a flow meter.
Page 53: Setting Parameters For The S/Sl Splitless Mode
Inlets Table 9 Splitless mode inlet parameters Parameter Allowed setpoint range Suggested starting value Gas saver time 0 to 999.9 minutes After purge time Gas saver flow 15 to 1000 mL/min 15 mL/min greater than maximum column flow Setting parameters for the S/SL splitless mode Mode The current operating mode—splitless Oven temperature Below solvent boiling point Temperature Actual and setpoint inlet temperatures...
Page 54: Setting Parameters For The S/Sl Pulsed Modes
Inlets Enter a Purge time and a Purge flow. If desired, turn on Gas saver. Make certain the time is set after the Purge time. Press [Prep Run] (see “Pre Run and Prep Run” on page 40) before manually injecting a sample (this is automatic for Agilent ALS).
Page 55: About The Multimode Inlet
Inlets About the Multimode Inlet The Agilent Multimode (MMI) Inlet System has five operating modes: • The split mode is generally used for major component analyses. • The pulsed split mode is like the split mode, but with a pressure pulse applied to the inlet during sample introduction to speed the transfer of material to the column.
Page 56: Heating The Mmi
Inlets With higher inlet pressures, tighten the septum retainer until the C- ring stops turning, indicating that the retainer is in firm contact with the septum. If using a Merlin Microseal™ septum, finger tighten the septum nut, until snug (not loose). The pressure capacity depends on the duckbill seal used.
Page 57: Mmi Split Mode Minimum Operating Pressures
Inlets If using cryo as the coolant when configuring the initial inlet setpoint, set the Use cryo temperature equal to or higher than the inlet setpoint to cool the inlet and hold the setpoint until the inlet temperature program exceeds the Use cryo temperature.
Page 58: Selecting The Correct Mmi Liner
Inlets Table 10 Approximate minimum viable inlet pressures for MMI in split mode, in psi (kPa) Split vent flow (mL/min) 50–100 100–200 200–400 400–600 Helium and hydrogen carrier gases Split liners - 5183-4647, 19251-60540 2.5 (17.2) 3.5 (24.1 4.5 (31) 6.0 (41.4) Splitless liners - 5062-3587, 5181-8818 4.0 (27.6)
Page 59 Inlets Splitless liner The liner volume must contain the solvent vapor. The liner should be deactivated to minimize sample breakdown during the purge delay. Solvent vapor volume can be reduced by using Pulsed Splitless mode. Use the “Vapor Volume Calculator“ to determine vapor volume requirements. Vapor volume <...
Page 60: Vapor Volume Calculator
Inlets Table 12 Splitless mode liners (continued) Liner Description Volume Mode Deactivated Part Number 4 mm Dual Taper Direct column connect G1544-80700 Vapor Volume Calculator Agilent provides a Vapor Volume Calculator to help you determine if a liner is suitable for a method. To use the calculator install the Agilent Instrument utility provided with the GC.
Page 61 Inlets Split Carrier supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Cold split introduction For cold split sample introduction, use an initial inlet temperature below the normal boiling point of the solvent.
Page 62 Inlets A single temperature ramp is enough for the injection process. The remaining ramps may be used to clean the liner or to reduce the inlet temperature in preparation for the next injection. Hot split introduction For hot split introduction, set an initial temperature high enough to volatilize the analytes.
Page 63 Inlets Saver flow Reduced split vent flow, at least 15 mL/min. Saver time Time when flow is reduced to save gas. If all columns in the flow path are defined Press [Front Inlet]. Scroll to Mode: and press [Mode/Type]. Select Split or Pulsed split.
Page 64: Mmi Splitless And Pulsed Splitless Modes
Inlets MMI splitless and pulsed splitless modes In these modes—with or without a pressure pulse—the split vent valve is closed during injection and vaporization of the sample and stays so while the sample transfers to the column. At a specified time after injection, the valve opens to sweep vapors left in the liner out the split vent.
Page 65 Inlets Stage 2. Solvent purging After the sample has transferred to the column, the split vent valve opens to purge remaining solvent vapor from the inlet. Split Carrier supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap Inlet Weldment FS = Flow Sensor...
Page 66 Inlets Timelines This figure summarizes the flow, pressure, and temperature changes during a splitless mode analysis. Split vent flow Purge flow Saver flow Inlet is pressure controlled Purge Prep Start Saver Stop Post Inlet pressure Time Time Time Post pressure Column mode = Constant flow Inlet pressure Purge...
Page 67 Inlets Cold splitless introduction For cold splitless introduction, use an initial inlet temperature below the normal boiling point of the solvent. For most solvents, starting the first inlet temperature ramp at 0.1 minutes provides good transfer and reproducibility. A program rate of 500 °C/min or higher is appropriate for thermally stable analytes.
Page 68 Inlets Some experimentation is needed to refine the operating conditions. Table 13 provides starting values for the critical parameters. Table 13 Splitless mode inlet parameters Parameter Allowed setpoint range Suggested starting value No cryo, ambient+4 °C to 450 °C Oven temperature 10 °C below solvent cryo, –40 °C to 450 °C boiling point...
Page 69 Inlets Pulse time Pressure returns to its normal setpoint at this time. Purge time The time, after the beginning of the run, when you want the split vent valve to open. Purge flow The flow, in mL/min, from the split vent, at Purge time.
Page 70: Mmi Solvent Vent Mode
Inlets Enter the Purge time when you wish the split valve to open. Set Total flow greater than the column flow plus the septum purge flow to guarantee adequate column flow. Turn Gas saver on, if desired. Set the time after Purge time. Press [Prep Run] (see “Pre Run and Prep Run”...
Page 71 Inlets Stage 1. Sample and vent During sampling and venting, the split valve is open. The inlet is at Initial temperature, which is at or below the solvent boiling point. Solvent vapors are swept out the vent, while sample deposits on the liner walls or packing.
Page 72 Inlets Stage 2. Sample transfer When solvent venting ends, the split valve vent closes and the inlet heats to Final temperature 1. The sample transfers to the capillary column during Purge time. (Purge flow to split vent in a data system). Carrier Supply Septum Purge 80 PSI...
Page 73 Inlets mimics traditional splitless operation and transports the analytes from the liner to the column. The purging mode allows the user to prepare the inlet for the next run. A fundamental difficulty with solvent vent mode is the potential loss of volatile analytes with the solvent. Several solutions are possible for this situation: •...
Page 74 Inlets Table 14 The solvent vent process (continued) Step Parameter Value Inlet pressure Column pressure setpoint Solvent venting ends, analyte transfer begins as inlet heats up. At Purge time Flow at split vent Purge flow setpoint Inlet pressure Column pressure setpoint Analyte transfer ends, inlet is purged of residual vapor.
Page 75 Inlets Time Oven temperature Inlet temperature Inlet pressure Split vent flow Controlled by column Saver or Between runs flow or pressure setpoint Purge flow or program Prep Run Start Run Vent flow Vent pressure Initial time Vent end time Rate 1 Inlet is pressure Initial time...
Page 76 Inlets These additional injections take time. The inlet and oven temperature programs, mainly the Initial time values, must be adjusted to allow for this. So must the various time values that control the inlet operation. This is discussed in more detail under “To develop a MMI method that uses large volume injection”...
Page 77 Inlets Table 15 Minimum attainable pressures Vent flow (mL/min) Actual vent pressure at Actual vent pressure at “0“ psig setpoint “0” kPa setpoint 1000 12.7 Vent flow The flow of carrier gas out the split vent during the vent period. Higher flows sweep the liner more quickly and reduce the time for solvent elimination.
Page 78: Mmi Direct Mode
Inlets If desired, turn Gas saver on. Make certain the time is set after the Purge time. Press [Prep Run] (see “Pre Run and Prep Run” on page 40) before manually injecting a sample. If the column is not defined Set up the parameters as described for the defined column case.
Page 79: To Develop A Mmi Method That Uses Large Volume Injection
Inlets Split Carrier supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column To develop a MMI method that uses large volume injection This topic provides a recommended way to change from a splitless injection using a split/splitless inlet to a solvent vent mode injection using a Multimode inlet (MMI).
Page 80 Inlets The main advantage of the MMI's solvent vent mode is that you can inject slowly into the inlet, allowing large amounts of solvent to evaporate in the liner (not in the split vent line), concentrating the analytes prior to injection. This requires an injector with variable speed injections, a "large"...
Page 81 Inlets Set up the inlet to perform a 1 uL injection. Use the split/splitless inlet method conditions, except: • Start with the inlet temperature cold, near but slightly below the solvent boiling point. For example, if using methylene chloride (boiling point 39 °C), start with a temperature of 30–39 °C.
Page 82: Multiple Injections With The Mmi
Inlets • The vent time is too long. The inlet started to heat while the vent was open. If the response of early eluters is too low: • The inlet temperature is too high. • The Vent Flow is too high. If the response of late eluters is too low: •...
Page 83 Inlets MSD ChemStation Software revision E.02.00 SP2 or later EZChrom Software revision 3.3.2 or later Setting parameters for the inlet in solvent vent mode Set or configure the following parameters in the data system's 7890A GC method editor. Syringe size — Verify the syringe size is configured correctly. The configured syringe size changes the available choices for injection volume.
Page 84 Inlets Table 17 Inlet parameters Name Value Name Value Initial temp 40 °C Rate 2 (off) Initial time 0.3 min Pressure 15.6 psig Rate 1 720 °C/min Vent pressure 0.0 psig Final temp 1 450 °C Vent flow 100 mL/min Final time 1 5 min Vent end time...
Page 85 Inlets These results were compared with a splitless analysis of the same sample, which should produce 100% recovery of all analytes. The data showed that, under these conditions, compounds above C were completely recovered and that the recovery was independent of injection size. Compounds lower than C were partially vented with the solvent.
Page 86 Inlets • Raise the inlet initial temperature to vaporize more solvent and allow more to be eliminated. This also increases the loss of volatile analytes since their vapor pressures also increase. To improve recovery of low boiling analytes • Reduce inlet temperature to lower the vapor pressure of the analytes and trap them more effectively.
Page 87 Inlets The result is shown in the next figure. Note the difference in the vertical scale (5000 versus 500). Advanced Operation Manual...
Page 88: About The Packed Column Inlet
Inlets About the Packed Column Inlet This inlet is also known as the purged packed inlet (PP). It is used with packed columns when high- efficiency separations are not required. It can also be used with wide- bore capillary columns, if flows greater than 10 mL/min are acceptable.
Page 89 Inlets Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Inlet Weldment FS = Flow Sensor Column PS = Pressure Sensor The next figure shows the flow diagram for the packed column mode, with the column not defined the control is based on total carrier gas flow.
Page 90: Setting Parameters
Inlets Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Packed Column Setting parameters The inlet can operate in flow or pressure control mode. Flow is recommended for packed columns. Pressure is recommended for capillary columns.
Page 91 Inlets flow, or Ramped flow. The column control mode is set from the Column parameters display. When the Inlet control mode is Flow control, only column flow can be set on the Column parameters display. Temperature The setpoint and actual temperature values. Pressure The actual pressure (in psi, bar, or kPa) supplied to the inlet.
Page 92: About The Cool On-Column Inlet
Inlets About the Cool On-Column Inlet This inlet introduces liquid sample directly onto a capillary column. To do this, both the inlet and the oven must be cool at injection, either at or below the boiling point of the solvent. Because the sample does not vaporize immediately in the inlet, problems with sample discrimination and sample alteration are minimized.
Page 93: Setup Modes Of The Coc Inlet
Inlets Setup modes of the COC inlet The COC inlet hardware must be set up for one of three usages, depending on the type of injection and column size. • 0.25 mm or 0.32 mm automated on- column. Use predrilled septa. •...
Page 94: Setting Coc Inlet Flows/Pressures
Inlets Track oven mode In the Track oven mode, the inlet temperature stays 3 °C higher than the oven temperature throughout the oven program. You cannot enter a temperature setpoint—it is set automatically. If you have CryoBlast, the inlet will track oven temperatures to –40°C;...
Page 95: Setting Coc Inlet Parameters
Inlets Setting COC inlet parameters Track oven mode Press [Front Inlet] or [Back Inlet]. Press [Mode/Type] and select Track oven. There is no setpoint for Track oven mode. Ramped temperature mode Press [Front Inlet] or [Back Inlet]. Press [Mode/Type] and select Ramped temp. Enter a value for Temp.
Page 96: About The Ptv Inlet
Inlets About the PTV Inlet The Agilent Programmed Temperature Vaporization (PTV) Inlet System has five operating modes: • The split mode is generally used for major component analyses. • The pulsed split mode is like the split mode, but with a pressure pulse applied to the inlet during sample introduction to speed the transfer of material to the column.
Page 97: Heating The Ptv Inlet
Inlets Septum head Septumless head The flow diagrams in the rest of this document show the septum head in place with a separate drawing for the septumless head. Heating the PTV inlet The control parameters for PTV temperature programming are the same as for the column oven, but are reached by pressing [Front Inlet].
Page 98: Cooling The Ptv Inlet
Inlets • The inlet can be programmed downward—just set the Final temp below the previous temperature—to reduce thermal stress on the inlet. • Downward programming can be used to prepare the inlet for the next run. This can reduce cycle time for greater sample throughput.
Page 99 Inlets Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Cold split introduction For cold split sample introduction, use an initial inlet temperature below the normal boiling point of the solvent.
Page 100 Inlets A single temperature ramp is enough for the injection process. The remaining ramps may be used to clean the liner or to reduce the inlet temperature in preparation for the next injection. Hot split introduction For hot split introduction, set an initial temperature high enough to volatilize the analytes.
Page 101 Inlets Total flow These are the actual and setpoint values of the total flow into the inlet, which is the sum of the split flow, column flow, and septum purge flow. When you change the total flow, the split ratio and split flow change while the column flow and pressure remain the same.
Page 102: Ptv Inlet Splitless And Pulsed Splitless Modes
Inlets Subtract the septum purge flow and split vent flow from Total flow to get column flow. Calculate the split ratio (split vent flow/column flow). Adjust as needed PTV inlet splitless and pulsed splitless modes In these modes—with or without a pressure pulse—the split vent valve is closed during injection and vaporization of the sample and stays so while the sample transfers to the column.
Page 103 Inlets Stage 1. Sample injection With the split vent valve closed, the sample and solvent transfer to the column. Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap PTV Inlet Weldment FS = Flow Sensor PS = Pressure Sensor Column Advanced Operation Manual...
Page 104 Inlets Stage 2. Solvent purging After the sample has transferred to the column, the split vent valve opens to purge remaining solvent vapor from the inlet. Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Split Vent Trap PTV Inlet Weldment FS = Flow Sensor...
Page 105 Inlets Split vent flow Purge flow Saver flow Inlet is pressure controlled Prep Start Purge Saver Stop Post Inlet pressure Time Time Time Post pressure Column mode = Constant flow Inlet pressure Prep Start Purge Stop Post Inlet Time Time temperature Final temp 1 Initial temperature...
Page 106 Inlets For most applications of cold splitless, a single temperature ramp is enough. The remaining ramps can be used to clean the liner or to decrease the inlet temperature to prepare for the next injection. Hot splitless introduction For hot splitless introduction, select an initial temperature high enough to volatilize the analytes.
Page 107 Inlets Table 21 Splitless mode inlet parameters (continued) Parameter Allowed setpoint range Suggested starting value ≥ Inlet purge time Oven initial time 0 to 999.9 minutes Inlet purge time 0 to 999.9 minutes 2 x Liner volume Column flow Gas saver time 0 to 999.9 minutes After purge time Gas saver flow...
Page 108 Inlets Purge flow The flow, in mL/min, from the split vent, at Purge time. You will not be able to specify this value if operating with your column not defined. Total flow The Total flow line displays the actual flow to the inlet during a Pre- run (Pre- run light is on and not blinking) and during a run before purge time.
Page 109: Ptv Inlet Solvent Vent Mode
Inlets Press [Prep Run] (see “Pre Run and Prep Run” on page 40) before manually injecting a sample. This is automatic if an Agilent sampler is used. PTV inlet solvent vent mode This mode is typically used for large volume injections. For single injection use a 50 or 100 µL syringe with variable plunger speed—slowly, 5 to 30 seconds.
Page 110 Inlets Stage 1. Sample and vent During sampling and venting, the split valve is open. The inlet is at Initial temperature, which is at or below the solvent boiling point. Solvent vapors are swept out the vent, while sample deposits on the liner walls or packing.
Page 111 Inlets Stage 2. Sample transfer When solvent venting ends, the split valve vent closes and the inlet heats to Final temperature 1. The sample transfers to the capillary column during Purge delay time. Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit...
Page 112 Inlets mimics traditional splitless operation and transports the analytes from the liner to the column. The purging mode allows the user to prepare the inlet for the next run. A fundamental difficulty with solvent vent mode is the potential loss of volatile analytes with the solvent. Several solutions are possible for this situation: •...
Page 113 Inlets Table 22 The solvent vent process (continued) Step Parameter Value Inlet pressure Column pressure setpoint Solvent venting ends, analyte transfer begins as inlet heats up. At Purge time Flow at split vent Purge flow setpoint Inlet pressure Column pressure setpoint Analyte transfer ends, inlet is purged of residual vapor.
Page 114 Inlets Time Oven temperature Inlet temperature Inlet pressure Split vent flow Controlled by column Saver or Between runs flow or pressure setpoint Purge flow or program Prep Run Start Run Vent flow Vent pressure Initial time Vent end time Rate 1 Inlet is pressure Initial time...
Page 115 Inlets These additional injections take time. The inlet and oven temperature programs, mainly the Initial time values, must be adjusted to allow for this. So must the various time values that control the inlet operation. This is discussed in more detail under “To develop a PTV method that uses large volume injection”...
Page 116 Inlets Table 23 Minimum attainable pressures (continued) Vent flow (mL/min) Actual vent pressure at Actual vent pressure at “0“ psig setpoint “0” kPa setpoint 1000 12.7 Vent flow The flow of carrier gas out the split vent during the vent period. Higher flows sweep the liner more quickly and reduce the time for solvent elimination.
Page 117: To Develop A Ptv Method That Uses Large Volume Injection
Inlets Press [Prep Run] (see “Pre Run and Prep Run” on page 40) before manually injecting a sample. If the column is not defined Set up the parameters as described for the defined column case. Set Total flow greater than the column flow plus the septum purge flow to guarantee adequate column flow.
Page 118 Inlets Injection speed Estimate the evaporation rate of solvent exiting the needle based on solvent type, inlet temperature, vent flow, and pressure. Start with about half that number. Note that you have to make sure that you configure the syringe properly. If not, you will over- or under- load the inlet.
Page 119 Inlets • Set a Vent flow of 100 mL/min as a starting point. • Keep the inlet isothermal for now. • Enter a Vent pressure of 0 psi (0 kPa) and Vent end time of 0.1 minutes. Make an injection using the empty vial. Use a stopwatch or your GC's timer feature to time how long the needle is in the inlet.
Page 120: Multiple Injections With The Ptv Inlet
Inlets Set a new vent time and initial inlet temperature time based on the new time the needle spends in the syringe. Make a 25 uL injection of your standard. Again, you should see 5 times the response. If not, see step 13. If you need more response, repeat steps through increase to larger volume.
Page 121 Inlets Preinjection washes and pumps are performed only before the first injection of a multiple injection set. Postinjection washes are performed only after the last injection in a multiple injection set. An example These values were used for a sample with a broad range of boiling points.
Page 122 Inlets Table 26 Oven parameters Name Value Rate 1 25 °C/min Final temp 1 320 °C Final time 1 10.0 min Rate 2 (off) Table 27 Detector parameters Name Value Detector Detector temp 400 °C Hydrogen flow 40 mL/min Air flow 450 mL/min Makeup (N 45 mL/min...
Page 123 Inlets These results were compared with a splitless analysis of the same sample, which should produce 100% recovery of all analytes. The data showed that, under these conditions, compounds above C were completely recovered and that the recovery was independent of injection size. Compounds lower than C were partially vented with the solvent.
Page 124 Inlets • Raise the inlet initial temperature to vaporize more solvent and allow more to be eliminated. This also increases the loss of volatile analytes since their vapor pressures also increase. To improve recovery of low boiling analytes • Reduce inlet temperature to lower the vapor pressure of the analytes and trap them more effectively.
Page 125 Inlets The result is shown in the next figure. Note the difference in the vertical scale (5000 versus 500). Advanced Operation Manual...
Page 126: About The Volatiles Interface
Inlets About the Volatiles Interface The volatiles interface provides a simple, reliable way to introduce a gas sample into your GC from an external device such as a headspace, purge and trap, or air toxic sampler. Manual syringe injections cannot be made with this interface.
Page 127: Vi Operating Modes
Inlets goes to the gas- phase sampler and from there is introduced into the interface. The second stream, called the pressure sensing line, passes through the frit block and is measured by a pressure sensor. This stream also provides a trickle flow to the interface.
Page 128: About The Vi Split Mode
Inlets Table 30 Specifications of the volatiles interface (continued) Specification Value/Comment Temperature range 10 °C above ambient (with oven at ambient) to 400 °C ≥ transfer line temperature of the Recommended temperature: external sampling device About the VI split mode When you introduce a sample in the split mode, a small amount of the sample enters the column while the major portion exits from the split vent.
Page 129 Inlets Carrier Supply Split Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Frit Gas Sampling Valve Headspace Purge and Trap Split Vent Trap FS = Flow Sensor PS = Pressure Sensor Column Setpoint dependencies Some setpoints are interdependent. If you change one setpoint, other setpoints may change to compensate.
Page 130 Inlets Table 32 Setpoint dependencies (continued) When you change These setpoints change Column defined Column not defined Column flow Pressure not available Split flow Total flow Split flow Split ratio not available Total flow Split ratio Split flow not available Total flow Total flow Split flow...
Page 131 Inlets Split ratio The ratio of split flow to column flow. Column flow is set using [Col 1] or [Col 2]. This parameter is not available if your column is not defined. Split flow Flow, in mL/min, from the split vent. This parameter is not available if your column is not defined.
Page 132: About The Vi Splitless Mode
Inlets Calculate the split ratio (split vent flow/column flow). Adjust as needed. If desired, turn Gas saver on. Set Saver time after the sample has been introduced. If Gas saver is on, be certain Auto prep run is On (see “Pre on page 40) or press [Prep Run] before Run and Prep Run”...
Page 133 Inlets Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Frit Gas Sampling Valve Headspace Purge and Trap Split Vent Trap FS = Flow Sensor Column PS = Pressure Sensor During sampling Pressure upsets caused by switching valves and trap restrictions in the external sampling device can cause fluctuations in column flow rates.
Page 134 Inlets During this user- specified sampling period, the solenoid valve is closed. Flow to the interface is measured by a flow sensor and controlled by a proportional valve. Split Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Valve Frit...
Page 135 Inlets Setpoint dependencies Some setpoints in the flow system are interdependent. If you change one setpoint, other setpoints may change to compensate. Table 34 Setpoint dependencies When you change These setpoints change Column defined Column not defined Purging You can change the Pressure and Total flow setpoints;...
Page 136 Inlets Table 35 Suggested starting values Parameter Allowed setpoint range Suggested starting value ≥ Interface purge time Oven initial time 0 to 999.9 minutes Ambient + 10 °C to 400 °C ≥ Transfer line Interface temperature temperature Interface sampling end 0 to 999.9 minutes 0.2 minutes longer than introduction time...
Page 137: About The Vi Direct Mode
Inlets Purge flow The flow, in mL/min, from the split vent at Purge time. You will not be able to access or specify this value if your column is not defined. Total flow When your column is defined, Total flow displays the actual flow to the interface.
Page 138 Inlets Before Pre Run The interface is forward pressure controlled; pressure is sensed downstream from the flow proportional valve. Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Frit Gas Sampling Valve Headspace Purge and Trap FS = Flow Sensor Column PS = Pressure Sensor During sampling...
Page 139 Inlets Flow to the interface is measured by a flow sensor and controlled by a proportional valve. Carrier Supply Septum Purge 80 PSI EPC Module Frit Frit Valve Valve Frit Gas Sampling Valve Headspace Purge and Trap FS = Flow Sensor Column PS = Pressure Sensor After sampling end...
Page 140: Preparing The Interface For Direct Sample Introduction
Inlets Preparing the Interface for Direct Sample Introduction Before you can operate your interface in direct mode, you must: • Disconnect the split vent line • Configure the GC for a direct injection Disconnecting the split vent line Be careful! The interface may be hot enough to cause burns. WA R N I N G Press [Front Inlet] or [Back Inlet].
Page 141 Inlets Loosen the hex nut connecting the split vent line to the interface until you can remove the line. Put the line aside. You do not need to plug it. Install a blanking nut into the split line port and finger- tighten the nut.
Page 142: Vi Direct Mode Setpoint Dependencies
Inlets Restore the GC to normal operating conditions. Perform a leak test on the interface fittings. Configuring the GC for a direct injection The GC cannot sense the presence of the split vent. When you disconnect or reconnect the vent, you must configure the GC so that the pneumatics work properly.
Page 143: Setting Parameters For The Vi Direct Mode
Inlets Table 37 Suggested starting values Parameter Allowed setpoint range Suggested starting value ≥ interface sampling end Oven initial time 0 to 999.9 minutes Ambient + 10 °C to ≥ transfer line Interface temperature 400 °C temperature Interface sampling end 0 to 999.9 minutes 0.2 minutes longer than actual sampling time...
Page 144 Inlets Set Sampling end at 0.2 minutes longer than the sample introduction time. Make certain Auto Prep Run is On (see “Pre Run and Prep Run” on page 40) or press before introducing a [Prep Run] sample. Advanced Operation Manual...
Page 145 Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Columns and Oven About the Oven Oven safety Configuring the Oven Cryogenic Operation Cryogenic setpoints About Oven Temperature Programming Programming setpoints Oven ramp rates Setting the oven parameters for constant temperature Setting the oven parameters for ramped temperature...
Page 146: Columns And Oven
Columns and Oven About the Oven Table 38 Oven capabilities Capability Range Temperature range –80 °C (liquid N ) or –40 °C (CO ) to the configured limit Maximum temperature 450 °C Temperature programming Up to six ramps Maximum run time 999.99 minutes Temperature ramp rates 0 to 120 °C/min, depending on...
Page 147: Configuring The Oven
Columns and Oven Configuring the Oven Oven configuration sets maximum temperature, equilibration time the cool down mode, and the cryogenic setpoints, if cryo is installed. Maximum temperature Maximum allowable oven temperature setpoint. Some accessories, such as the valve box, valves and columns have specific temperature limits.
Page 148: Cryogenic Operation
Columns and Oven Cryogenic Operation The cryogenic valve lets you operate the oven below ambient temperature. Minimum attainable oven temperature depends on the type of valve installed. The GC senses the presence and type of cryogenic valve and disallows setpoints if no valve is installed. When cryogenic cooling is not needed or cryogenic coolant is not available, the cryogenic operation should be turned off.
Page 149 Columns and Oven If the temperature goes below the minimum allowed temperature (–90 °C for liquid nitrogen, –70 °C for liquid ), the oven will shut down. External oven mode Isothermal internal mode and programmed external oven used to calculate column flow. Slow oven cool down mode On to run oven fan at slow speed during cool down.
Page 150: About Oven Temperature Programming
Columns and Oven About Oven Temperature Programming You can program the oven temperature from an initial temperature to a final temperature using up to 20 ramps during a run. A single ramp temperature program raises the initial oven temperature to a specified final temperature at a specified rate and holds at the final temperature for a specified period of time.
Page 151: Oven Ramp Rates
Columns and Oven Final temperature Temperature of the oven at the end of a heating or cooling rate. Final time Time in minutes that the oven will be held at the final temperature of a temperature- programmed rate. Total length of a run is determined by its oven temperature program.
Page 152: Setting The Oven Parameters For Constant Temperature
Columns and Oven Setting the oven parameters for constant temperature An isothermal run is one in which the oven is maintained at a constant temperature. For an isothermal run, set Rate 1 to zero. Press [Oven] to open the oven parameter list. Enter the oven temperature for the isothermal run.
Page 153 Columns and Oven To add additional oven ramps, repeat the steps described. Advanced Operation Manual...
Page 154: About The Oven Insert
Columns and Oven About the Oven Insert The Oven Insert for Fast Chromatography reduces the oven volume so that the column and sample heat more quickly, yielding faster separation and faster chromatography. Furthermore, the smaller volume oven cools faster than a full- sized oven, reducing the overall analytical cycle time.
Page 155: About Columns
Columns and Oven About Columns In all GCs, a sample—which is a mixture of several components—is vaporized in an inlet, separated in a column, and examined in a detector. The column separates components in time because: • When a vaporized component is presented with a gas phase and a coating phase, it divides between the two phases according to its relative attraction to the two phases.
Page 156: Select A Column Mode
Columns and Oven • Constant flow—Maintains a constant mass flow rate of carrier gas in the column throughout the run. If the column resistance changes due to a temperature program, the column head pressure is adjusted to keep the flow rate constant.
Page 157: Setting The Column Parameters For Constant Flow Or Constant Pressure
Columns and Oven Press [Mode/Type] to see the column mode list. Scroll to the column mode you want. Press [Enter]. This completes column mode selection. Next you must specify the inlet conditions either during the entire run (if you selected either of the constant modes) or at the beginning of the run (if you selected either of the ramped modes).
Page 158: Programming Column Pressure Or Flow
Columns and Oven remains at that value for Final time 1. You can then add a second and third ramp, each consisting of a Rate, a Final value (pressure or flow), and a Final time. The program ends when it reaches a Rate that is set to 0 (Off).
Page 159: Backflushing A Column
Columns and Oven Backflushing a Column Backflush is a means of discarding high- boilers from a column after the peaks of interest have eluted. It saves analysis time and has these additional benefits: • Longer column life • less high temperature exposure •...
Page 160: Backflushing When Connected To An Msd
Columns and Oven Backflushing when connected to an MSD If using an MSD with the GC, backflushing becomes more complex. Set up backflush as a post run event by using the Backflush Wizard present in the MSD Productivity ChemStation. Backflushing using a capillary flow technology device Because the following capillary flow technology (CFT) devices connect to a controlled carrier gas supply, they can be used to backflush a column:...
Page 161 Columns and Oven To set up a post run backflush A main advantage of the post- run backflush method is that the GC turns off detection during this time. If using an MSD, this helps prevent damage to the detector and is the recommended backflush method.
Page 162 Columns and Oven When developing the backflush portion of your method, consider the following: • Ensure that the split vent flow setpoint is at least 25 mL/min and at least 50% more than the column backflush flow rate. • If using gas saver, ensure that the gas saver flow setpoint is at least 25 mL/min and at least 50% more than the column backflush flow rate.
Page 163 Columns and Oven To backflush using a ramped flow program In this case, the backflush occurs as part of the run, so the detectors continue to collect data. During the backflush, you may wish to turn off data collection in the data system. To avoid damage to an MSD, Agilent strongly recommends setting C A U T I O N up backflush as a post run event, not as part of a ramped column...
Page 164 Columns and Oven The Run Table contains commands to perform these actions: • After the last peak of interest appears, switch the valve to Position 2. Higher boiling peaks are discarded through the inlet vent. • At the same time, turn data acquisition off. •...
Page 165: Nickel Catalyst Tube
Columns and Oven Nickel Catalyst Tube About the nickel catalyst tube The Nickel Catalyst Tube accessory, G2747A, is used for trace analysis of CO and CO with a flame ionization detector. The gas sample is separated on the column and passed over a heated catalyst in the presence of hydrogen, which converts the CO and CO peaks to CH...
Page 166: Setting Temperatures For The Nickel Catalyst Tube
Columns and Oven Table 41 Gas flows for a TCD/FID series installation Flow rate, mL/min Carrier (helium) TCD switching flow FID hydrogen 45 (see Caution) FID air Hydrogen flow is pressure-controlled, where an FID provides a C A U T I O N known resistance.
Page 167: Detectors
Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Detectors About Makeup Gas About the FID About the TCD About the uECD About the NPD About the FPD+ About the FPD Agilent Technologies...
Page 168: About Makeup Gas
Detectors About Makeup Gas Most detectors use a makeup gas to increase the flow rate through the detector body. This sweeps peaks out of the detector quickly, avoiding mixing of components and loss of resolution. This is particularly important with capillary columns because the column flow rates are so small.
Page 169: About The Fid
Detectors About the FID The FID passes sample and carrier gas from the column through a hydrogen- air flame. The hydrogen- air flame alone creates few ions, but burning an organic compound increases the number of ions produced. A polarizing voltage attracts these ions to a collector located near the flame.
Page 170: How Fid Units Are Displayed In Agilent Data Systems And On The Gc
Detectors Makeup EPC Module Vent Frit Frit Frit Valve Valve Valve Restrictor Restrictor Restrictor PS = Pressure Sensor Column Table 42 Properties of the FID Property Value/Comment Dynamic range 1 x 10 Sensitivity 10 to 100 picograms of an organic compound dependent on the molecular structure.
Page 171: To Light The Fid Flame
Detectors Table 43 Unit conversions Data system Height units LSV (height units) Area units Noise (ASTM) Agilent data system 1 pA 1.3 x10 1 pA-sec 0.038 pA † SIGRange 1 x 10 1.3 x 10 1 x 10 0.038 pA SIGRange 5 3.2 x 10 4.2 x 10...
Page 172: Recommended Starting Conditions For New Fid Methods
Detectors To change Lit offset: Press [Config][Front Det] or [Config][Back Det]. Scroll to Lit offset. Enter the new value and press [Enter]. Recommended starting conditions for new FID methods Table 44 for guidelines and rules to select initial detector settings for new methods. Table 44 Recommended starting conditions Combustible gas mix...
Page 173: Setting Parameters For Fid
Detectors Table 44 Recommended starting conditions (continued) 200 to 600 * Detector hydrogen is pressure controlled, where the detector provides a known resistance. If using a nickel catalyst tube, the resistance changes, and the flow rates displayed by the GC will not be accurate. Measure the actual hydrogen flow using a flow meter at the detector vent, with all other flows turned off.
Page 174: About The Tcd
Detectors About the TCD The TCD compares the thermal conductivities of two gas flows—pure carrier gas (the reference gas) and carrier gas plus sample components (the column effluent). This detector contains a filament that is heated electrically so that it is hotter than the detector body. The filament temperature is held constant while alternate streams of reference gas and column effluent pass over it.
Page 175 Detectors Column effluent Column effluent is forced away from is forced toward the filament. TCD the filament. TCD measures reference gas. measures peaks (if present). Advanced Operation Manual...
Page 176: Tcd Pneumatics
Detectors TCD pneumatics This is the pneumatics design of the TCD. Makeup Reference Gas Vent Valve EPC Module Restrictor Frit Frit Reference switching valve Valve Restrictor PS = Pressure Sensor Column TCD carrier, reference, and makeup gas Reference and makeup gas must be the same as the carrier gas, and the gas type must be specified in both the inlet and detector parameter lists.
Page 177: Tcd Gas Pressures
Detectors Ratio of reference flow to column + makeup flow Column + makeup flow, mL/min TCD gas pressures Choose a flow, find a pressure, set source pressure 10 psi (70 kPa) higher. Hydrogen Helium Reference gas flow, mL/min Nitrogen Pressure (psig) kPa) Advanced Operation Manual...
Page 178: Selecting Reference And Makeup Flows For The Tcd
Detectors Hydrogen Makeup gas flow, mL/min Helium Nitrogen Pressure (psig) kPa) Selecting reference and makeup flows for the TCD Table 45 Recommended flow rates and temperatures Gas type Flow range Carrier gas Packed, 10 to 60 mL/min (hydrogen, helium, nitrogen) Capillary, 1 to 5 mL/min Reference 15 to 60 mL/min...
Page 179: Changing The Tcd Polarity During A Run
Detectors compounds may attack the filament. The immediate symptom is a permanent change in detector sensitivity due to a change in filament resistance. If possible, such compounds should be avoided. If this is not possible, the filament may have to be replaced frequently. Changing the TCD polarity during a run Negative polarity On inverts the peak so the integrator or ChemStation can measure it.
Page 180: Setting Parameters For The Tcd
Detectors Setting parameters for the TCD Press [Front Det] or [Back Det]. Set the detector temperature. Do not set higher than the maximum temperature allowed for the column because part of the column passes through the heated block and into the cell. Verify that makeup gas type is the same as that plumbed to your instrument (next to Makeup line in the parameter list).
Page 181 Detectors Example: Capillary mode (small capillary columns) If combined column plus makeup flow is between 5 and 10 mL/min, set the reference flow at 3× the combined flow. For a combined flow between 10 and 15 mL/min, use a multiplier of 2. This will bring the TCD within 25% of the maximum response.
Page 182: About The Uecd
Detectors About the uECD The micro- cell detector (uECD) contains a cell plated with Ni releases β particles that Ni, a radioactive isotope. The collide with carrier gas molecules to produce low- energy electrons—each β particle produces approximately 100 electrons. The free electrons produce a small current—called the reference or standing current—that is collected and measured in a pulsed circuit.
Page 183: Uecd Warnings
Detectors uECD licenses Customers in the United states can purchase an exempt model uECD. Customers outside the United States should contact their local Agilent sales office for information. uECD warnings Although beta particles at this energy level have little penetrating power —the surface layer of the skin or a few sheets of paper will stop most of them—they may be hazardous if the isotope is ingested or inhaled.
Page 184: Safety Precautions When Handling Uecds
State regulation. For other countries, consult with the appropriate agency for equivalent requirements. Agilent Technologies recommends a vent line inside diameter of 6 mm (1/4 inch) or greater. With a line of this diameter, the length is not critical.
Page 185: Uecd Gas Flows
Detectors uECD gas flows Anode purge and makeup gas Restrictor Frit Vent Valve Restrictor Capillary adapter EPC Module PS = Pressure Sensor Column uECD linearity The uECD response factor versus concentration curve is linear for four orders of magnitude or more (linear dynamic range = 10 or higher) for a broad range of compounds.
Page 186: Uecd Analog Output
Detectors elution temperature of the last compound. If you operate at excessively high temperatures, your results will not necessarily improve and you may increase sample and column decomposition. uECD analog output If you intend to use the analog output from the uECD, you must set the output Range to 10.
Page 187: Uecd Temperature Programming
Detectors uECD chromatographic speed (for fast peaks) can be increased by increasing the makeup gas flow rate. uECD temperature programming The uECD is flow sensitive. If you are using temperature programming, in which the column flow resistance changes with temperature, set up the instrument as follows: •...
Page 188: About The Npd
Detectors About the NPD New NPD features and changes The NPD firmware in this GC (A.01.08 or higher) is considerably different from that in earlier versions and from the 6890 firmware. Major changes are: • Equilibration time parameter has been removed. •...
Page 189: Npd Flow, Temperature, And Bead Recommendations
Detectors minimizing hydrocarbon ionization, while the alkali ions on the bead surface facilitate ionization of nitrogen- or phosphorus- organic compounds. The output current is proportional to the number of ions collected. It is sensed by an electrometer, converted to digital form, and sent to an output device.
Page 190 Detectors Table 49 General operating values (continued) Gas or Setting Recommendation Capillary makeup (helium, nitrogen) Ceramic bead Nitrogen: 5 to 10 mL/min Helium: less than 5 mL/min Blos bead 1 to 20 mL/min Temperature Default is 250 °C; operating range is 150 °C to 400 °C. •...
Page 191: Npd Required Gas Purity
Detectors Flow, mL/min Helium Nitrogen Pressure (psig) kPa) Hydrogen Flow, mL/min Pressure (psig) kPa) Temperature programming The NPD is flow sensitive. If you are using temperature programming, in which the column flow resistance changes with temperature, set up the instrument as follows: •...
Page 192: Setting Parameters For The Npd
Detectors all detector gases, including the detector hydrogen, air, and makeup gases. Do not use plastic (including PTFE) tubing, plastic- bodied traps, or O- ring seals. Setting parameters for the NPD Before operating the NPD, make sure that detector gases are connected, a column is installed, and the system is free of leaks.
Page 193: Selecting An Npd Bead Type
Detectors column in the constant pressure mode, choose Column +makeup=constant. If your column is not defined, enter a makeup gas flow. Only constant flow is available. Monitor the offset adjustment process. If Auto Adjust is On, the adjust offset process starts automatically when the detector reaches setpoint.
Page 194: Changing From A Ceramic Bead To A Blos Bead
Detectors Changing from a ceramic bead to a Blos bead The Blos bead is more delicate than the ceramic beads, and may be C A U T I O N distorted during shipping. Before installing a Blos bead, verify that it is centered and adjust it if necessary.
Page 195: To Configure The Npd
Detectors 51.5 mm 43 mm 43 mm Figure 1 Capillary optimized NPD jets For the adjustable NPD, select one of the following from Table Table 52 Jets for adaptable fittings Figure 4 ID Jet type Part number Jet tip id Length Capillary with extended jet G1534-80590...
Page 196: Automatically Adjusting Npd Bead Voltage
Detectors Auto Adjust Bead Recommended On. When On, the automatic adjust offset process starts when the bead reaches the temperature setpoint after having been turned off or cooled below 150 °C. Auto adjust starts after Dry Bead hold time, if enabled.
Page 197: Setting Npd Adjust Offset On The Clock Table
Detectors Detector off When the detector is off, Adjust offset and Bead voltage are Off and initial Output is displayed. Detector on—detector temperature less than 150 °C. When you enter an Adjust offset value or press [On], detector gases turn on and the display blinks the Temp not ready message.
Page 198: Setting The Initial Bead Voltage For New Beads
Detectors • Keep the detector temperature high (320 to 335 °C). • Turn the hydrogen flow off during solvent peaks and between runs. Turning hydrogen off during a solvent peak When using the NPD, the baseline shifts after a solvent peak and can take some time to stabilize, especially with chlorinated solvents.
Page 199: Setting Npd Bead Voltage Manually (Optional)
Detectors Setting NPD bead voltage manually (optional) Bead voltage shows the voltage used to heat the bead. It can be a value derived from the Adjust offset value, or can be entered as a setpoint. Entering a setpoint causes the voltage to change at 13 mV/second until it reaches the setpoint provided that •...
Page 200: About The Fpd
Detectors About the FPD The sample burns in a hydrogen- rich flame, where some species are reduced and excited. The gas flow moves the excited species to a cooler emission zone above the flame where they decay and emit light. A narrow bandpass filter selects light unique to one species, while a shield prevents intense carbon emission from reaching the photomultiplier tube (PMT).
Page 201: Fpd + Linearity
Detectors linearity Several mechanisms produce sulfur emission. The excited species is diatomic, so that emission intensity is approximately proportional to the square of the sulfur atom concentration. The excited species in the phosphorus mode is monatomic, leading to a linear relationship between emission intensity and atom concentration.
Page 202: Fpd + Temperature Considerations
Detectors temperature considerations The FPD provides two temperatures zones, one for the transfer line (the main detector temperature) and one for the emission block. For the transfer line temperature, we recommend a temperature that is 25 °C higher than the highest column temperature.
Page 203: Lighting The Fpd + Flame
Detectors Table 53 Recommended flows mL/min Carrier (hydrogen, helium, nitrogen, argon) Packed columns 10 to 60 Capillary columns 1 to 5 Detector gases Hydrogen Carrier + makeup Helium, either as carrier or makeup gas, may cool the detector gases below the ignition temperature. We recommend using nitrogen rather than helium.
Page 204: Setting Parameters For The Fpd
Detectors Manual ignition Press [Front Det] or [Back Det]. Scroll to Flame. Press [On/Yes]. The flame ignition sequence begins. Automatic ignition If the FPD output with the flame on falls below the flame- off output plus the Lit offset value, this is interpreted as a flame- out condition.
Page 205 Detectors shown next to Makeup in the parameter list. Change the gas type, if necessary. If your capillary column is defined, choose a flow mode and set the makeup gas flow or combined flow. If your capillary column is not defined, enter a makeup gas flow.
Page 206: About The Fpd
Detectors About the FPD The sample burns in a hydrogen- rich flame, where some species are reduced and excited. The gas flow moves the excited species to a cooler emission zone above the flame where they decay and emit light. A narrow bandpass filter selects light unique to one species, while a shield prevents intense carbon emission from reaching the photomultiplier tube (PMT).
Page 207: Fpd Linearity
Detectors FPD linearity Several mechanisms produce sulfur emission. The excited species is diatomic, so that emission intensity is approximately proportional to the square of the sulfur atom concentration. The excited species in the phosphorus mode is monatomic, leading to a linear relationship between emission intensity and atom concentration.
Page 208: Inlet Liners For Use With The Fpd
Detectors The phosphorus filter is yellow/green and transmits at 525 nanometers. Inlet liners for use with the FPD Compounds containing sulfur may adsorb on an inlet liner and degrade the GC’s performance. Use deactivated, clean liners or a cool on- column inlet, which injects directly onto the column.
Page 209: Lighting The Fpd Flame
Detectors Table 54 Recommended flows (continued) Sulfur mode flows, Phosphorus mode mL/min flows, mL/min Detector gases Hydrogen Carrier + makeup Helium, either as carrier or makeup gas, may cool the detector gases below the ignition temperature. We recommend using nitrogen rather than helium. Lighting the FPD flame Before trying to light the flame, have the detector at operating temperature.
Page 210: Setting Parameters For The Fpd
Detectors Manual ignition Press [Front Det] or [Back Det]. Scroll to Flame. Press [On/Yes]. The flame ignition sequence begins. Automatic ignition If the FPD output with the flame on falls below the flame- off output plus the Lit offset value, this is interpreted as a flame- out condition.
Page 211 Detectors surface, such as a mirror or chrome- plated wrench, over the vent exit. Steady condensation indicates that the flame is lit. Advanced Operation Manual...
Page 212 Detectors Advanced Operation Manual...
Page 213 Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Valves About Valves The Valve Box Heating the valves Valve temperature programming Configuring an Aux thermal zone Valve Control The valve drivers The internal valve drivers The external valve drivers Valve Types...
Page 214: About Valves
Valves About Valves Valves may be used to alter the usual inlet/column/detector flow path in the GC. Sampling valves can replace the inlet, switching valves can select columns, multiposition valves, used in conjunction with sampling valves, can perform the same functions for sample streams that an ALS performs for liquid samples.
Page 215: The Valve Box
Valves The Valve Box The GC holds up to four valves in a heated valve box on top of the oven. The valve box is the preferred location for valves because it is a stable temperature zone, isolated from the column oven. Back of chromatograph Valve heater blocks...
Page 216: Valve Temperature Programming
Valves Valve temperature programming Most valve applications are isothermal; however, you can define three temperature ramps if desired. Press [Aux Temp #], then [1] or [2]. Program this ramp the same as an oven ramp. Refer to “Setting the oven parameters for ramped temperature”...
Page 217: Valve Control
Valves Valve Control Valves can be controlled manually from the keyboard or as part of a clock or run time program. Note that only sampling valves automatically reset at the end of a run. Other valve types remain at the new position until activated again. For other valve types, you must include any desired resets in the program.
Page 218: The External Valve Drivers
Valves Keyboard Connector V1 Connector V2 Internal valve drivers Run table (1 through 4) Connector V3 Connector V4 Clock table There is no direct relationship between the location of a valve in the valve box and the driver that controls it. This depends on how the solenoids are wired and the actuators are plumbed.
Page 219: Valve Types
Valves Valve Types The possible valve types are: Sampling A two- position (load and inject) valve. In load position, an external sample stream flows through an attached (gas sampling) or internal (liquid sampling) loop and out to waste. In inject position, the filled sampling loop is inserted into the carrier gas stream.
Page 220: Configuring A Valve
Valves Configuring a Valve Press [Config]. Scroll to Valve #. Enter the valve number and press [Enter]. The current valve type is displayed. To change the valve type, press [Mode/Type], select the new valve type, and press [Enter]. Advanced Operation Manual...
Page 221: Controlling A Valve
Valves Controlling a Valve From the keyboard Valves (except multiposition valves) have two positions controlled by the [On] and [Off] keys. The keyboard commands for two- position valves are: [Valve #] <scroll to the valve> [On] Rotates valve to one stop [Valve #] <scroll to the valve>...
Page 222: Gas Sampling Valve
Valves Use a run table entry to ensure that the valve is in the Off state between runs. Gas sampling valve If a valve is configured as a gas sampling valve, it starts a run automatically when it is switched to the Inject position. This can be done with a keyboard command or by a subsequence or clock table entry.
Page 223: Multiposition Stream Selection Valve With Sampling Valve
Valves Load time Time in minutes that the valve remains in the Load position before becoming ready. Inject time Time in minutes that the valve remains in the Inject position before returning to the Load position. The sampling valve cycle is: The sampling valve rotates to the Load position.
Page 224 Valves Sampling valve Multiposition stream selection valve Sample streams in Selected stream out If the GC has one valve configured as a multiposition valve and another configured as a gas or liquid sampling valve, it assumes that they are to be used in series. This “double configuration”...
Page 225 Agilent 7890 Series Gas Chromatograph Advanced Operation Manual GC Output Signals About Signals Signal Types Value Analog Signals Analog zero Analog range Analog data rates Selecting fast peaks (analog output) Digital Signals Digital zero Signal Freeze and Resume Data rates with Agilent data systems...
Page 226: About Signals
GC Output Signals About Signals Signal is the GC output to a data handling device, analog or digital. It can be a detector output or the output from flow, temperature, or pressure sensors. Two signal output channels are provided. Signal output can be either analog or digital, depending on your data handling device.
Page 227: Signal Types
GC Output Signals Signal Types When assigning detector signals, use the [Mode/Type] key and choose from the Signal Type parameter list, or press a key or combination of keys. [Front], [Back], [–], and [Column Comp] will work, alone or in combination.
Page 228 GC Output Signals Table 56 Signal conversions (continued) Signal type 1 display unit is equivalent to: Pneumatic: Flow 1 mL/min Pressure 1 pressure unit (psi, bar, or kPa) Diagnostic Mixed, some unscaled Advanced Operation Manual...
Page 229: Analog Signals
GC Output Signals Analog Signals If you use an analog recorder, you may need to adjust the signal to make it more usable. Zero and Range in the Signal parameter list do this. Analog zero Zero Subtracts value entered from baseline. Press [On/Yes] to set to current Value or [Off/No] to cancel.
Page 230: Analog Data Rates
GC Output Signals A: Range = 0 B: Range = 3 C: Range = 1 There are limits to usable range settings for some detectors. The table lists the valid range setpoints by detector. Table 57 Range limits Detector Usable range settings (2 0 to 13 0 to 13 0 to 13...
Page 231: Selecting Fast Peaks (Analog Output)
GC Output Signals Selecting fast peaks (analog output) Press [Config][Analog 1] or [Config][Analog 2]. Scroll to Fast peaks and press [On]. Agilent does not recommend using Fast peaks with a thermal conductivity detector. Since the gas streams switch at 5 Hz, the gain in peak width is offset by increased noise.
Page 232: Digital Signals
GC Output Signals Digital Signals The GC outputs digital signals only to an Agilent data system. The following discussions describe features that impact the data sent to data systems, not the analog data available to integrators. Access these features from the data system.
Page 233: Data Rates With Agilent Data Systems
GC Output Signals Baseline upset due to valve switch Pause signal here Resume signal here Data rates with Agilent data systems The GC can process data at various data rates, each corresponding to a minimum peak width. The table shows the effect of data rate selection.
Page 234 GC Output Signals Table 58 EZChrom/ChemStation data processing (continued) Data rate, Hz Minimum peak Relative Detector Column type width, minutes noise 0.02 0.04 All types 0.22 0.16 0.10 0.07 Slow packed You cannot change the data rate during a run. You will see higher relative noise at the faster sampling rates.
Page 235: Zero Init Data Files
GC Output Signals Relative noise level Excess noise (due to flow, oven temperature, detector block temperatures, etc.) Faster data rates Slower data rates Zero Init Data Files This feature applies to digital output only, and is mainly intended for non- Agilent data systems. It may help systems that have trouble with non- zero baseline output.
Page 236: Column Compensation
GC Output Signals Column Compensation In temperature programmed analysis, bleed from the column increases as the oven temperature rises. This causes a rising baseline which makes peak detection and integration more difficult. Column compensation corrects for this baseline rise. A column compensation run is made with no sample injected.
Page 237: Creating A Column Compensation Profile
GC Output Signals Creating a column compensation profile Set up the instrument for a run. Make a blank run to verify that the baseline is clean. This is particularly important for new conditions or if the GC has been idle for several hours. Press [Column Comp].
Page 238: Plotting A Stored Column Compensation Profile
GC Output Signals This changes the digital output. You cannot get both compensated and uncompensated digital data from the same detector at the same time. However, it does not affect the analog output. Plotting a stored column compensation profile Press [Analog Out 1] or [Analog Out 2]. Scroll to Type: and press [Mode/Type].
Page 239: Test Plot
GC Output Signals Test Plot Test plot is an internally generated “chromatogram” that can be assigned to a signal output channel. It consists of three baseline- resolved, repeating peaks. The area of the largest is approximately 1 Volt- sec, the middle one is 0.1 times the largest, and the smallest is 0.01 times the largest.
Page 240 GC Output Signals Advanced Operation Manual...
Page 241 Agilent 7890 Series Gas Chromatograph Advanced Operation Manual Auxiliary Devices Auxiliary Devices About Auxiliary Pressure Control About Aux Thermal Zone Control About Cryo Trap Control About Auxiliary Device Contacts About the 24V Auxiliary Device Power Supply About Auxiliary Columns About Auxiliary Detectors...
Page 242: Auxiliary Devices
Auxiliary Devices Auxiliary Devices About Auxiliary Pressure Control Pressure units There are two common ways of expressing gas pressures: psia Absolute pressure, measured relative to vacuum. psig Gauge pressure, measured relative to atmospheric pressure. This name is used because most pressure gauges have one side of the sensing element exposed to the atmosphere.
Page 243: About Aux Thermal Zone Control
Auxiliary Devices Setting parameters for auxiliary pressure control Press [Aux EPC #] and scroll to the channel you wish to control. Press [Enter]. Scroll to Initial pressure. Enter a value and press [Enter]. If desired, enter a pressure program using the time and rate functions.
Page 244: About Auxiliary Device Contacts
Auxiliary Devices To use the cryo trap during a run: Press [Aux Temp #] and scroll to the zone you wish to control. Press [Enter]. Scroll to Temperature. Press [On/Off] to turn the zone on or off, as desired (typically, On). Scroll to Cold Trap Temperature.
Page 245: About Auxiliary Detectors
Auxiliary Devices About Auxiliary Detectors The GC supports up to two auxiliary detectors in addition to the Front and Back detectors that mount on the top of the oven. Aux Det # 1 This can only be a TCD, and mounts in a carrier on the left side of the oven together with its flow module.
Page 246 Agilent Technologies...

Agilent Technologies 7890 Series Advanced Operation Manual

Table of Contents

1 Programming

2 Flow and Pressure Modules

3 Inlets

4 Columns and Oven

Columns and Oven

Detectors

6 Valves

7 Gc Output Signals

Quick Links

Chapters

Related Manuals for Agilent Technologies 7890 Series

Summary of Contents for Agilent Technologies 7890 Series