Performing a GC Manual Injection Using OpenLab CDS

Answer

This Information Applies To: Agilent GC systems (8890, 8860, 7890, 7820, 6890, 6850, 6820) using Agilent OpenLab CDS

Issue

Manual injections are needed for a gas chromatograph without an automated sampler. They are also used for troubleshooting specific issues such as no peaks, lower peaks than expected, ghost peaks, and other chromatographic problems.

Items Required

• GC syringe
• Suitable sample or standard

Steps to Follow

Prepare your syringe, sample, and hardware

1. Locate a suitable syringe. If you have an ALS (7683 or 7693), you can use the syringe from the injector tower. See Removing and Installing a Syringe on the Agilent 7693A Autosampler.

2. Prepare a sample or standard.

3. Verify that the syringe is working.

   1. Manually draw up some sample or solvent (put the end of the syringe in the liquid, then pull up the plunger to draw up the liquid).

   2. Push the plunger down to eject the liquid onto a paper towel.

   3. Verify that you can see the drops exit the syringe. If not, the syringe is clogged.

4. Prepare the hardware so the top of the inlet is easily accessible. You need to be able to see the green septa nut (Figure 1):

Figure 1. Septa nut for an SSI and MMI

• • For the 7683 and 7693 ALS injector towers: remove these by lifting them off the support rod and put on the parking post on the rear of the GC (if present) or elsewhere.
  • For headspace systems: depending on the transfer line connection, you may need to remove the transfer line.
  • For Purge & Trap and PAL systems: these should not need any changes

Prepare the method in the software

For a Sequence

1. From the top ribbon, go to the Home tab, and click the Sequence button.
2. In the Sequence Table, locate the Injection source column. For every sequence line, from the drop-down menu in the column, select No Injection/Instrument Blank (Figure 2). This command will bypass the ALS. 
3. Start the sequence.

Figure 2. Sequence Injection source 

For a Single Sample

1. From the top ribbon, go to the Home tab, and click the Single Sample button.
2. In the Single Sample Analysis window, scroll down to the Autosampler section
3. From the Injection source drop-down list, select Injection source, then select No Injection/Instrument blank (Figure 4).
4. To start the run, in the Single Sample Analysis window, click the Run button.

Figure 4. Single Sample Analysis

Perform the manual injection

1. Enable Prep Run on the GC:
   • On the 6850, 6890, 7820, and 7890: press the [Prep Run] button on the GC keypad.
   • On the 8860 and 8890: press the prep run icon at the bottom right off the GC touch screen in the Home view
2. Manually draw up the sample into a syringe. Put the needle tip into the sample vial below the liquid level, and pull up the syringe to the desired volume.
3. Carefully put the syringe needle into the GC inlet, by pushing it through the tiny silver funnel in the center of the green septa nut.
4. Push the plunger down, pushing the sample into the GC inlet and immediately start the run by:
   • On the 6850, 6890, 7820, 7890: Press the [Start] button on the GC keypad
   • On the 8860 and 8890: press the icon on the GC touch screen

Learn how to effectively operate your Agilent Gas Chromatography: Agilent 7890 Series GC with OpenLab CDS Agilent 8860 GC with OpenLab CDS Agilent 8890 GC with OpenLab CDS e-learning courses available from Agilent education