Abstract |
There is an increasing need for multicomponent gas standards containing volatile toxic organic compounds at the low parts-per-billion level for use in environmental monitoring programs. Standards containing many organic compounds, both halogenated and nonhalogenated species within the same mixture, can be very difficult to analyze at the 1-15 ppb concentration level. Analyses of low level multicomponent mixtures have been done using several different techniques. Gas chromatography has been used to separate compounds in simple and complex mixtures. Original work was done using packed columns with a flame-ionization detector (FID) and large sample volumes, 10 mL and an electron-capture detector (ECD) to analyze for halogenated compounds at low ppb levels. Therefore, to measure all the compounds in a single analysis, a cryogenic preconcentration technique was developed to increase the sensitivity of both types of compounds to the FID. Temperature programming was coupled with this cryogenic preconcentration technique to increase the quality of baseline separations. |