PURGE-AND-TRAP GAS-CHROMATOGRAPHY DETERMINATION OF STYRENE AND ETHYLBENZENE - PERFORMANCE IN MODEL MEDIUM

Ethylbenzene, styrene and propylbenzene were determined by an automate d dynamic headspace system. Hydrocarbons were purged on a cold trap an d separated on a GC column. The procedure was applied without sample m anipulation on model media such as peanut oil and a mixture of peanut oil and NaCl saturated water. Purge conditions were optimized with res pect to temperature, purge gas (helium, hydrogen). A preliminary bubbl ing of CO2 or a first purge into water increases strongly the desorpti on of these hydrocarbons. Helium proved to be better than hydrogen as purge gas.