Determination of 2, 2'-methylene bis(3, 4, 6-trichlorophenol) in environmental samples by GC

Trace level of hexachlorophene [2, 2'-methylene bis (3, 4, 6-trichlorophenol)] (HC) in environmental samples were purified successfully by a combination of liquid-liquid extraction, methylation with diazomethane followed by clean-up on an open column. Determination was performed by GC with electron capture detection. The aqueous sample was extracted with hexane at pH 4. HC in the hexane extract was transferred into 5 M sodium hydroxide-ethanol (1 : 1, v/v), and the alkaline extract, re-adjusted to pH 4 with hydrochloric acid, which was then extracted with hexane. The extract was evaporated to dryness, and the residue was dissolved in diethylether. HC in the sediment sample was extracted with 5 M sodium hydroxide-ethanol(1 : 1, v/v) and the alkaline extract was washed with hexane, further extraction and evaporation to dryness was carried out in the same way as the aqueous sample. The sample of the diethylether solution was placed in an outer tube of the apparatus used for preparing diazomethane. A diazomethane, formed by the action of alkali on N-methyl-N-nitroso-N'-nitroguanidine in an inner tube of the apparatus, was collected in the diethylether solution and HC was converted to the methyl ether. The methylated solution was then dried with nitrogen and taken up in hexane and placed on the top of a clean-up column containing silica gel. The methyl ether of HC was eluted with hexane-diethylether(50 : 1, v/v). The eluate was concentrated and analyzed by gas chromatograph with 2% Silicone OV-1 column and electron capture detector(ECD). Recoveries of the HC from aqueous samples and sediments were 8192% with a 1.45.0% of relative standard deviation, the detection limit was 0.005 μg/l and 0.002 μg/g, respectively.