Vernier Go Direct Mini GC Quick Start Manual page 7

enough that you do not bend the plunger if the plunger sticks. The larger
injection sizes require greater care during the injection.
Rinsing the Syringe
1. Submerge the tip of the syringe needle in the rinse liquid, commonly
acetone or ethanol, and draw the plunger back to 50% of its total volume.
2. Remove the syringe from the rinse liquid and place the tip of the needle
over an appropriate waste receptacle such as a beaker or lint-free tissue.
3. Slowly depress the plunger, ejecting all of the solution from the syringe.
4. Wipe the needle of the syringe with a fresh lint-free tissue.
5. Repeat the above steps 3 times.
6. Remove the syringe tip from the solution, replace the cap of the vial of rinse
liquid, and wipe the needle of the syringe with a fresh lint-free tissue.
Collecting a Sample
1. Remove the cap from the sample container and rinse the syringe with the
solution to be injected, following the procedure outlined in the section
Rinsing the Syringe.
2. Submerge the tip of the needle in the solution to be injected and slowly
draw the plunger back by an amount larger than the intended injection
volume. This excess volume will typically be somewhere around 0.1 µL.
(Example: If you are attempting a 0.2 µL injection, you should withdraw
between the 0.25 and 0.3 µL.)
3. Remove the syringe tip from the solution and replace the cap on the sample
container.
4. Holding the syringe vertically at eye level, carefully depress the plunger
until the syringe holds only the desired injection volume.
5. Carefully wipe the syringe needle with a fresh lint-free tissue, making sure
the tissue does not absorb any sample from inside the needle.
6. When you are satisfied with the volume of your sample, proceed to
injection. If not, carefully eject the syringe contents into the appropriate
waste receptacle, wipe the needle with a fresh lint-free tissue, and begin
again at Step 2.
Injecting into the Go Direct Mini GC
1. Wait for the status indicator light on the Go Direct Mini GC to turn green
and the message "Ready for Injection" to appear before collecting your
sample into the syringe.
2. As soon as your sample is loaded into the syringe, grip the syringe by the
flange and pinch the needle about halfway along its length.
3. Aim the needle into the center of the brass needle guide at the top of the gas
chromatograph and slowly push the needle into the injection port, being
careful not to move the plunger. If the needle should catch, immediately stop
pushing and turn the syringe a quarter turn, then resume pressure.
4. As soon as the syringe is fully inserted against the needle guard, quickly
depress the plunger and simultaneously click Collect in the data-collection
software.
5. Immediately pull the syringe out of the gas chromatograph.
Cleaning the Syringe
Never force the plunger.
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Clean the syringe following the procedure described in Rinsing the Syringe
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using an appropriate solvent. Choose a solvent that will dissolve the
contaminating substances. Common choices include acetone, methanol,
methylene chloride, and acetonitrile, but other solvents may be used. Non-
alkaline, non-phosphate, non-detergent solvents are preferred. Do not soak
the syringe in any solvent.
If the plunger is catching during injection, it may need to be flushed with
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multiple cleaning solvents.
Troubleshooting
If the syringe plunger will not fully depress
Follow the procedure for cleaning the syringe.
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Inspect the plunger. If it is bent and cannot be straightened, dispose of the
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syringe according to your sharps disposal procedure.
Appendix D
Relationship of Pressure and Column Flow Rate
If you are accustomed to setting flow rate rather than column pressure values in
a temperature-pressure profile, here is an equation (and a table of typical values)
representing the nearly linear relationship between these two variables:
Flow Rate (mL/min) = 0.54×Pressure (kPa)
Pressure (kPa) Flowrate (mL/min)
2.5
5.0
7.5
10.0
12.5
15.0
17.5
20.0
This relationship was determined by measuring the flow rate of the exiting gas
(air) when the column was heated at a constant 45°C temperature at various
pressures.
7
1.4
2.7
4.1
5.4
6.8
8.1
9.5
10.8