CONTINUOUS-FLOW THIN-LAYER HEADSPACE (TLHS) ANALYSIS .6. COMPARISON OF THE RESULTS OF THE DETERMINATION OF VOLATILE ORGANOHALOGEN COMPOUNDS IN TAP WATER IN THE FORM OF A GROUP PARAMETER (VOX) WITH PARTIAL SPECIATION BY DAI-ECD CAPILLARY GAS-CHROMATOGRAPHY (GC)2

A comparison is presented of the accuracy of the conductometric and indirect potentiometric methods of VOX determination in tap water (using the TLHS isolation technique) with gas chromatographic results obtained by direct aqueous injection and electron capture detection (DAI-ECD). The agreement was very good. The conductometric method has been further examined by comparing the results of VOX determintion obtained in the continuous mode with the gas-chromatographic results. Also in this case, the agreement was satisfactory, proving that the conductometric method can be successfully applied for monitoring the VOX level in tap waters. The theory of the TLHS technique has been further developed, enabling a simple determination of the critical values of some important parameters. The expression b(cr,inf) congruent-to (2 . 2)2.(3.3)-3 approximates the critical value of the synthetic parameter b with an error not exceeding 8 . 10(-6). Direct practical utilization of the derived dependences for the optimization of the analysis is possible, provided that the values of the effective partition coefficients of the analytes and their mineralization products under given experimental conditions are known.