Supplies and Services for Mass Spectrometers, Gas Chromatographs
and Liquid Chromatographs
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27 | Last Update: 01/31/00 |
INTRODUCTION
A new GC Cryo-Trap was interfaced to a Gas Chromatograph with an automated GC Headspace system in order to develop an automated GC headspace method for the analysis of volatile organic compounds in contaminated soil samples utilizing capillary GC columns. The LEAP Headspace Auto Injector uses a heated syringe concept to directly inject 0.10 to 2.5 milliliter gas samples from the heated and agitated headspace sample vial into the GC injection port for subsequent trapping on a GC Cryo-Trap at the front of the GC column. The GC Cryo-Trap consists of a small heating/cooling chamber which surrounds the front 4 inches of the capillary or guard column. It is installed inside the GC oven, just under the GC injection port to permit the trapping of volatile organics at the front of the column. Liquid Nitrogen is utilized to permit the trapping of volatiles down to -180 degrees C.
The purpose of this study was to evaluate the usefulness of the GC Cryo-Trap in conjunction with the headspace injection technique for the analysis of volatile organics in soil, water and other samples utilizing capillary GC columns. The GC Cryo-Trap permits the injection of large gas sample volumes via techniques such as Headspace and Thermal Desorption. It eliminates the need to cool the entire GC oven for cryo-focusing samples on the column. During the entire injection process, the volatiles in the gas sample injected into the GC injection port are concentrated in a narrow band at the front of the GC capillary column. When the GC Cryo-Trap is subsequently heated, the trapped volatiles are released in a narrow band to be chromatographed via the GC capillary column.
