ANALYSIS OF VOLATILE ORGANIC-COMPOUNDS IN ESTUARINE SEDIMENTS USING DYNAMIC HEADSPACE AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

In our previous paper (J. Chromatoger., Vol. 467, p. III) we reported a modified variant of the purge-and-trap gas chromatographic analysis of volatile organic carbon compounds in water. In this paper we report the application of the modified open-loop dynamic headspace technique for the stripping and trapping of volatile organic compounds (VOCs) from estuarine sediments. Sediment samples (ca. 300-400 g wet weight) are transferred into all-glass l-l bottles and purged at 60-degrees-C for 70 min in an ultrapure helium gas stream. Volatile eluates are quantitatively trapped onto three different sorbent beds arranged in series. Analysis is then performed using thermal desorption with capillary column chromatography and simultaneous flame ionisation with ion-trap detection. As with water samples, stripping temperature had the greatest effect upon compound recovery, with smaller variances in recovery observed when comparing different sediment types. The method is capable of quantifying many individual volatile organic compounds down to a detection limit between 10 and 100 ng kg-1 (dry weight). The linear dynamic range for a broad range of compounds fell between the lower limit of detection to approximately 500-700-mu-g kg-1 (dry weight). The results of a case study on sediments taken from the Southampton Water estuary are presented as an example of the method application. A list of component concentration ranges are also presented.