Determination of Pentachlorophenol by Exhaustive Methylation and Capillary Gas Chromatography in Sewage Sludge, Contaminated Water and Suspended Particulates

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Abstract
A method for the determination of pentachlorophenol (PCP) in large volumes of sea water and suspended particulate matter is described. PCP is methylated using methyl iodide in the presence of tetra-butylammonium hydroxide (TBA). The methyl derivative, pentachloroanisole, is quantified by capillary gas chromatography using electron-capture detection. Recovery and the coefficient of variation of the analytical method are found to be: 78% and 4.6% respectively, (n = 17). The PCP is extracted from the sea water by liquid-liquid partition with pentane and sulphuric acid, and by soxhlet extraction with hexane:acetone, 40:60, plus sulphuric acid from the particulate matter. These extraction procedures are also effective for a wide range of other organic contaminants including sterols, chlorinated pesticides and PCBs. The sample clean-up and PCP separation are achieved by liquid-liquid extraction with alkali to isolate the acidic compounds. The PCP is back-extracted into organic solvent after acidifying the aqueous phase and raising the ionic strength. No further clean-up is needed. Following the method validation samples were taken after sewage sludge dumping operations and analysed for PCP in the water and particulate fractions. These results are reported.