Round robin study on precision of determinations of trihalomethanes in water.

Abstract

Round robin study was carried out to investigate the precision of the determinations of trihalomethanes in water by the solvent-extraction gas chromatographic (GC) method and the head-space GC method which are prescribed by the Japanese Ministry of Health and Welfare. Four samples of water with chloroform, bromodichloromethane, dibromochloromethane and bromoform were analyzed by 14 different laboratories : 13 laboratories measured the concentrations of the four compounds by the solvent-extraction GC method and 12 laboratories, by the head-space GC method. The results show that the intralaboratory precision was better than the interlaboratory precision by analysis of variance ; the precision of the results by the solvent-extraction GC method was better than those by the head-space GC method in many cases. The mean obtained by the head-space GC method was significantly larger than that obtained by the solventextraction GC method in some cases.