In order to achieve the best performance with headspace GC, careful attention should be paid to sample preparation and instrument setup. The vial and cap are a very important, and often overlooked, element in the headspace analysis preparation.

 

It is important to ensure the correct vial and cap are used!

• Vial Size

  Headspace vials are available in 6, 10 and 20ml sizes. Use a vial large enough to ensure adequate headspace or phase ratio without excessive dilution of the components of interest. Phase ratio is discussed later and should normally be at least 50% of the sample volume.

• Bottom Profile

  Headspace vials may be round-bottomed or flat-bottomed. Either type is suitable but round-bottomed vials tend to be stronger and may work more reliably when the autosampler moves the vials into and out of the incubator. Round-bottomed vials also tend to withstand higher pressures and are more suitable for elevated temperatures and applications such as derivatization.

• Correct Crimping

  Headspace vials must be correctly crimped. Ensure the crimper is not worn and is adjusted correctly. The cap should not turn after application to the vial. Find out more about correct vial crimping.

• Septa Choice

  Use septa suitable for the temperature of the system. Poor septa can result in bleed and so contaminate the headspace.

• Cleanliness of Vials

  Vials should be clean. Not all vials are the same and dirty or re-washed vials can cause ghost peaks or erroneous results.