Spiking Prior To Capping; Spiking After Capping; Full Evaporation Technique - Teledyne Tekmar Versa User Manual

spiking prior to capping

The advantage of spiking a vial prior to capping is that the septum remains uncompromised and the potential for
leakage is minimized.
When spiking a vial prior to capping, the following precautions should be taken:
1. When spiking into a liquid matrix, be sure to inject the spike below the meniscus of the sample to minimize
volatilization of the spiking material to the atmosphere.
2. When spiking into a solid matrix, inject the spike into or onto the surface of the material being analyzed.
3. Cap the sample immediately to minimize the loss of volatiles from the headspace.

spiking after capping

Sample headspace can escape from the small hole in the septum when pressurizing to high pressure, or when the
sample matrix is producing a high vapor pressure.
• Spiking after sealing the vial eliminates loss of volatiles to the atmosphere
• Spiking after the sample vial is capped also helps preserve the headspace integrity of the sample

fUll eVaporatIon technIqUe

The Full Evaporation Technique (FET) completely vaporizes a small aliquot of liquid sample in a sealed headspace vial.
It is often the first step in the headspace method development process. FET is used both as a quantitation tool for
standard headspace samples and a complete analysis of some samples because it can keep non-volatile or inorganic
material (such as salts or polymers) in the sample from entering the analytical system.
FET helps ensure your injection port, column, and detector remain as contaminant-free as possible to yield the highest
degree of precision, accuracy and sensitivity.
In the FET process, several microliters of a sample extract are injected into a headspace vial. The vial is then heated to a
temperature high enough to fully vaporize all the sample's volatile and semi-volatile components. (These components
are normally vaporized within the gas chromatograph's injection port in direct injections.) The vapor containing only
the volatile and semi-volatile compounds is then injected into the GC for final analysis. Any semi-volatile material
remains in the vial and does not enter the GC, preventing interference with the performance of the analytical system.
FET is an ideal method for the analysis of high molecular weight compounds, such as pesticides, polychlorinated
biphenyls, nitroaromatics and polynuclear aromatics. Generally, analysis of these compounds is complicated by the
complex matrices in which they are found.
FET can also eliminate the need for time-consuming clean-up procedures before direct injection of wastewater and
soil extractions. Because the extract is injected directly into the headspace vial, the vial serves as a disposal injection
port liner/pre-column.
To perform the Full Evaporation Technique, you will have to first determine the volume and concentration
requirements for the particular sample you want to run.
Versa User Manual
Installation & Setup • Page 3-5
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