Determination of volatile halogenated organic compounds in soils by purge-and-trap capillary gas chromatography with atomic emission detection

摘要

Nine volatile halogenated organic compounds(VHOCs),including four trihalomethanes(THMs),were determined in soils by capillary gas chromatography with microwave induced-plasma atomic emission spectrometry(GC-AED),using a purge-and-trap system(PT)for sample preconcentration.Analytes were previously extracted from the soil sample in methanol and the extract was preconcentrated before being chromatographed.Element-specific detection and quantification were carried out monitoring two wavelength emission lines,corresponding to chlorine(479 nm)and bromine(478 nm).Each chromatographic run took 21 min,including the purge step.The method showed a precision of 1.1-7.2%(R.S.D.)depending on the compound.Detection limits ranged from 0.05 to 0.55 ngml~(-1),for chloroform and dichloromethane,respectively,corresponding to 3.3 and 36.0 ngg~(-1)in the soil samples.The chromatographic profiles obtained showed no interference from co-extracted compounds.Low levels of dichloromethane and chloroform ranging from 0.04 to 1.13 M-gg~(-1)were found in samples obtained from small gardens irrigated with tap water.The method is reliable and can be used for routine monitoring in soil samples.