CONTINUOUS-FLOW THIN-LAYER HEADSPACE (TLHS) ANALYSIS .1. CONDUCTOMETRIC DETERMINATION OF VOLATILE ORGANIC HALOGENS (VOX) IN TAP WATER

A new method of a continuous determination of volatile organohalogens in water is presented, based on the so-called thin layer headspace (TLHS) technique. Volatile analytes are isolated from the aqueous phase in a thermostatted spiral tube (TLHS column), where the sample flows in a form of a thin film countercurrently to a stream of purified air. The isolated compounds are mineralized in an empty quartz tube at 900-degrees-C, and the mineralization products are washed with triply distilled water. The conductivity of the wash solution is proportional to the VOX concent. The detection limit is of the order of a few ppb. The effect of the possible interfering substances has been examined and a method for the elimination of the effect of sulfur is presented. The results of the analysis of natural tap water samples are given. The theory of the THLS process is discussed and has been verified experimentally.