Performing a GC Manual Injection with OpenLab ChemStation

Answer

This Information Applies To: Agilent 8890, 8860, 7890, 7820, 6890, 6850 GC systems

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

1. From the top menu, click Instrument > Select Injection Source... (Figure 2)
   

   
    
   Figure 2. Select Injection source...  
   
   

   1. In the Select Injection Source/Location dialog box, select the manual option, then select the injection location, and click OK (Figure 3).

      
      
      Figure 3. Select Injection Source/Location dialog box
      
      

   2. Save the acquisition method with a name that identifies it as manual injection.

   3. To start a single sample, from the top menu, click Run Control > Run Method (Figure 4)
      

      
      
      Figure 4. Run Method
      
      

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 GC system:  GC-0GEN-1040z - Practical Steps in GC Troubleshooting GC-8890-2200s - Agilent 8890 GC Maintenance and Troubleshooting e-learning courses available from Agilent education