COMPLEMENTARITY OF PURGE-AND-TRAP AND HEADSPACE CAPILLARY GAS-CHROMATOGRAPHIC METHODS FOR DETERMINATION OF METHYL-TERT-BUTYL ETHER IN WATER

An improved method has been developed for the quantitative determinati on of traces of methyl-tert.-butyl ether (MTBE) over a large range of concentrations in water samples based on two complementary techniques: head-space capillary gas chromatography and purge-and-trap gas chroma tography. The interesting aspect of this study lies in the complementa ry performances of these two methods, each in its specific range, for the analysis of MTBE in water samples. Head-space gas chromatography w as used as a screening technique in routine analyses, while purge-and- trap gas chromatography was used as a confirmation method for the nega tive results. The analytical precision was good with both methods. Det ection limits were 50 mu g l(-1) for head-space gas chromatography and 2 mu g l(-1) for purge-and-trap gas chromatography, with 90% calculat ed recovery. Choice of different parameters for the purge-and-trap met hod is discussed.