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

The use of trace enrichment techniques with high performance liquid chromatography-conductometric detection is described for the determination of very low concentrations (down to ppb) of dihardenedtallowdimethyl 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 environmental 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-equal-to 7%) for environmental samples and high recoveries of standard additions, generally greater-than-or-equal-to 90%, from all matrices. The detection limits of the procedure for environmental liquor and solid samples are estimated to be 2.5 mug/l and 0.5 mug/g, respectively. Its high specificity for the determination of DHTDMAC in a range of environmental samples is shown by comparing the results obtained with those for a standard non-specific colorimetric disulphine blue method. The procedure as detailed is suitable for DHTDMAC but could be adapted for determining other cationic surfactants.