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A method is described to permit automatic sampling of volatile organics in water for GC analysis.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
72% of the total text.
Page 1 of 1
Direct Purge - Injection Method for a Gas Chromatograph (GC)
A method is described to permit automatic sampling of volatile organics in
water for GC analysis.
A method is described of injecting a liquid sample into a gas chromatograph
whereby the total sample is not vaporized instantly and there is an increased
separation efficiency for the non-volatile components of interest.
The principal application of this method of injection is in the analysis of low
boiling trace organics in aqueous media by gas chromatography using a flame
ionization detector. However, the principle might well be applied to other sample
media and GC systems as well.
In conventional gas chromatography one or two microliters of liquid sample
are injected by syringe into a heated zone at the front end of the separating
column and vaporized instantly before the sample is swept by the carrier gas into
the column. Normally, instant vaporization of the total sample is considered
necessary to minimize distortion of the sample band before it enters the column.
Distortion of the initial sample band leads to reduced separation efficiency in the
As an alternative to total vaporization, this method describes a method where
the liquid sample is injected either by syringe or rotary liquid sample valve into a
length of unheated stainless steel capillary tubing (0.02" - 0.03" ID) which
connects to the separating column. When the aqueous sample enters the
capillary tube it spreads as a thin layer al...