System Pressure And Standby Flow; Transfer Line Temperature; Platen Equilibration Time; Inject Time - Teledyne Tekmar Versa User Manual

system Pressure and standby Flow

System pressure is preset to 18.0 +/-0.5psig and is adjustable to 28psig. System pressure is used to pressurize vials
and determines standby flow. Standby flow is the flow that is swept through the system to clean the lines and needle
between samples to prevent cross contamination and carryover. The preset standby flow rate is approximately
50mL/min. measured from the needle. Increasing system pressure will increase standby flow rate.
NOTE: Standby flow rate is measured at the sample needle. Flow measured at the vent will be reduced due to a
restrictive loop.

transfer Line temperature

The Transfer Line temperature should be set to the same, or 5° above, the valve oven temperature.

Platen equilibration time

Platen Equilibration Time is the time the Versa will wait for the Platen to equilibrate at the set temperature. The
main functionality is when multiple platen temperatures are being used within a schedule or when the unit is being
powered up to run. If the same platen temperature is always being used, this equilibration time can be set to a very
short time such as 0.0–0.5 minute.
NOTE: If Platen temperatures are going to be changing throughout a schedule, it is strongly advised to schedule
methods to start at the lowest temperature and move to the highest temperatures. The Platen heats much
more quickly than it cools. Therefore, by ordering samples to go from lower Platen temperatures to higher
temperatures a higher sample through-put is achieved.

inject time

There are two critical factors that need to be known to properly set the inject time, the GC carrier flow rate and the
loop size. Teledyne Tekmar recommends that a minimum volume of three times the loop size should be flushed
through the sample loop during inject to completely transfer the sample gas to the GC. To determine the proper time,
take the loop volume multiplied by three and then divide by the carrier flow rate.
NOTE: Longer injection times will not affect analytical performance, only sample through-put.

additionaL headsPaCe reFerenCes

The following are great sources for additional information on headspace analysis:
Static Headspace-Gas Chromatography Theory and Practice
Bruno Kolb & Leslie s. Ettre Wiley – VCH
Head-Space Analysis and Related Methods in Gas Chromatography
B.V. Ioffe & A.G. Vitenberg Wiley-Interscience Publication
A Technical Guide for Static Headspace Analysis Using GC
Restek Corporation http://www.restekcorp.com/restek/images/external/59895a.pdf
Versa User Manual
Method Development • Page 6-7
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