Supplies and Services for Mass Spectrometers, Gas Chromatographs
and Liquid Chromatographs
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29 | Last Update: 01/31/00 |
INTRODUCTION
A previous application note described the analysis of volatiles in latex base paints utilizing the headspace GC technique in conjunction with the GC Cryo-Trap. This application note extends these techniques to the analysis of volatiles in oil based paints. The combination of the headspace GC technique with the GC Cryo-Trap has proven to be a practical method for the analysis of latex paints as well as the oil based paints. The volatile content in the oil based paints is much higher than the water based paints; therefore, the methods have been modified to permit the analysis of the higher volatile levels in these samples. The following article will demonstrate the accuracy and reproducibility of this method.
The system consists of the LEAP CTC HS500 Automated Headspace Sampler mounted on top of the GC injection port and the SIS GC Cryo-Trap mounted inside the GC oven just under the injection port. The GC Cryo-Trap consists of a small heating/cooling chamber which surrounds the front 4 inches of the capillary or guard column. Liquid Nitrogen is utilized to permit the trapping of volatiles down to -180 degrees C. The GC Cryo-Trap permits the injection of large gas sample volumes and eliminates the need to cool the entire GC oven for cryo-focusing samples on column. During the headspace injection process, the volatiles in the gas sample when 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. This results in the generation of sharp, well resolved GC peaks.
