What should I do if the headspace is not picking up all the performance standard compounds or the area counts are too low?

Applies to: Chemical and Gas Headspace (GC/MS) | Tickets Solved: 5 | Rank: 3

Headspace not Picking up Performance Standard

If the headspace is not picking up all the performance standard compounds please check the following causes:

1. Check to see if the right standard is being used. The headspace uses a 4-part standard while the HAPSITE uses a 5-part standard. The HAPSITE 5-part standard is not concentrated enough to pass with the headspace.
2. Expiration date of the performance standard. Once opened, the chemicals have a thirty-day shelf life. As the performance standard ages, the chemicals begin to degrade and escape into the atmosphere. A QC run may not pass if the performance standard is past its life span.
3. Check to make sure you are injecting the right amount of standard. You should inject 8-10 micro liters of standard into 20 milliliters of water in the vial.
4. The condition of the syringe. The syringes used to dispense the performance standard can become clogged or the plunger might be loose causing an incorrect volume to be dispensed. Syringes should be cleaned with methanol before and after each use to prevent contamination and be sure to monitor the volume being delivered.
5. A bad lot of performance standard. Periodically, a bad lot is produced with not enough of one or more compounds, too much of one or more compounds, or a combination of both. If the performance standard is consistently failing while using multiple methods and if a pattern can be seen, you may need to purchase a new standard from a different lot.
6. Clogged headspace needle. If the needle is clogged, it will need to be replaced.
7. Transfer line with cold spots or clogging. Sometimes the transfer cable may be dirty on the inside with chemicals that might cause the performance standard chemicals to adhere to the transfer cable. If the transfer line is having any of these issues the line needs to be purged, cleaned or possibly replaced.
8. A tuning issue. Please refer to the document, “Introduction to the Manual Tune” to check the tune.

For more questions regarding this issue please contact technical support.

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Keywords: tune, PS, tranfer line, needle, internal