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Preparing a Sample
This chapter describes the steps necessary to prepare a sample for analysis,
including filling and sealing a sample vial and loading the sample tray.
Sample Preparation
The 7694 Headspace Sampler can accept either 10- or 20 ml sample vials. You
cannot mix vial sizes when loading the tray. Before using 10 ml vials, you must
insert adapters into the spaces in the sample tray and in the oven carousel.
Samples that will undergo headspace extraction are placed in the sampler in
glass vials. You also must flip the switch on the back of the horizontal loader to
the proper size setting.
In general, sample vials should be filled only about half way (although vials can
be filled to the 3/4 level). This ensures that the needle will not come into
contact with the solid or liquid phase during the sampling step.
The vial must be sealed properly to insure that the headspace gases do not
escape prematurely. Use a crimper designed for headspace vials with 20 mm
caps to seal the vials (Agilent part no. 9301–0720).
Note Sampling from an incorrectly capped vial may cause the 7694 Headspace
Sampler to jam during septum puncture.
Do the following to prepare a vial for sampling:
1. Place a septum in a vial cap with the Teflon side facing the vial. Take care
not to contaminate the septum.
2. Place the cap upside down on a table.
3. Place the sample in the vial. The vial should not be more than 50% full.
4. Place the septum and cap together over the vial opening.
5. Place the crimper over the cap and vial.
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