THE DETERMINATION OF DIHARDENED TALLOWDIMETHYL AMMONIUM-COMPOUNDS (DHTDMAC) IN ENVIRONMENTAL MATRICES USING TRACE ENRICHMENT TECHNIQUES ANDHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH CONDUCTOMETRIC DETECTION

The use of trace enrichment techniques with high performance liquid ch romatography-conductometric detection is described for the determinati on of very low concentrations (down to ppb) of dihardenedtallowdimethy l ammonium compounds (DHTDMAC), major cationic surfactants, in a range of environmental matrices. The applicability of the procedure to the analysis of DHTDMAC in sludges, sediments, soil and aqueous environmen tal samples has been demonstrated during the course of interlaboratory exercises. The HPLC procedure gives accurate and reproducible results (i.e. within laboratory standard deviations typically less-than-or-eq ual-to 7%) for environmental samples and high recoveries of standard a dditions, generally greater-than-or-equal-to 90%, from all matrices. T he detection limits of the procedure for environmental liquor and soli d samples are estimated to be 2.5 mug/l and 0.5 mug/g, respectively. I ts high specificity for the determination of DHTDMAC in a range of env ironmental samples is shown by comparing the results obtained with tho se for a standard non-specific colorimetric disulphine blue method. Th e procedure as detailed is suitable for DHTDMAC but could be adapted f or determining other cationic surfactants.