Glossary
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retention time The time interval from the moment of injection of a sample
into the column to the appearance of the peak maximum of the given
component in the eluate
sampling sequence In headspace analysis, the steps involved in removing the
sample from the vial and injecting it into the GC column. These steps include
puncturing the septum, pressurizing the vial, venting the vial and injecting the
headspace gas into the GC.
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sensitivity (of analytical method). The ratio of the analytical signal increment
to the corresponding increment of concentration (or contents) of the
determinant
setpoint Numerical value for an analytical step entered into a method
single headspace extraction The standard method of headspace analysis.
One headspace sample is taken from each sample vial being analyzed. See
multiple headspace extraction.
single puncture Multiple headspace extraction performed by piercing the
septum with the needle only once. The needle remains in the vial for all the
heating and sampling steps until it is withdrawn after the last extraction. See
multiple puncture.
split injection A injection method that allows very small amounts of sample
to be introduced to capillary columns. A homogeneous sample is split into two
portions in a known ratio; the smaller portion is introduced into the column
and the major part is allowed to escape.
splitless injection An injection with the entire injected volume applied to the
column
standard addition See internal standard
Thermal Conductivity Detector (TCD) A gas phase detector based upon
changes in the thermal conductivity of the gas stream. The thermal
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