[A gas chromatographic method to decrease the detection limit of trace benzene in CS2 extract].

A method to decrease the detection limit of trace benzene in CS2 extract from coastal water by gas chromatography has been studied. A direct injection port (Shimadzu WBI-17) and a 2 m x 2 mm i.d. column packed with Chromosorb W(AW-DMCS) coated with 10% SE-30 was used. It is simpler and has low detection limit, small sample amount and high repeatability. The experiment showed that the trace water in the organic phase and the too small purge flow of the direct injection port could cause serious tailing of CS2 peak. There was an optimum value of the purge flow (purge flow/total flow = 5%). The minimum detectable limit of benzene was 4 micrograms/L. The repeatability (RSD) was better than 6% and the average recovery was 96.7%.