ANALYSIS OF VOLATILE ORGANIC-COMPOUNDS IN AIR USING RETENTION INDEXESTOGETHER WITH A SIMPLE THERMAL-DESORPTION AND COLD TRAP METHOD

A simple, low-cost thermal desorption and cold trap device was constru cted and tested with a two-channel gas chromatograph equipped with SE- 54 fused-silica capillary columns or a Al2O3/KCl column and flame ioni zation, nitrogen-phosphorus or electron-capture detectors. Good repeat ability was obtained in the identification of ten aromatic compounds, with use of n-alkanes as index compounds for the determination of rete ntion indices. The performance of the equipment and method with real s amples was evaluated for the determination of volatile halogenated com pounds and small alcohols in urban air, and for the determination of N ,N-dimethylformamide (DMF) in air nearby a chemical plant. A collectio n method was developed for highly volatile halogenated hydrocarbons an d small polar alcohols. At ambient temperature they were not easily tr apped completely and humidity was a problem. Drying tubes were needed in front of the sampling tubes, which were placed inside copper tubes refrigerated in a cold box. Compounds were reliably identified, and so me of the halogenated compounds and DMF were determined quantitatively . (C) 1997 Elsevier Science B.V.