Determination of Chlorophenols in Soils by a Method Involving Alkaline Extraction and Solid-phase Preconcentration Prior to High-performance Liquid Chromatography

A well-reproducible method for determining five common chlorophenols in soils is described. Chlorophenols were extracted from a soil with sodium hydroxide and, after being acidified to pH 6.5, the extract was cleaned by partitioning between chloroform and sodium hydroxide. After adjusting the pH value to 5.5, the sample was concentrated in a C-18 minicolumn. The chlorophenols were desorbed with methanol, the extract was basified, the solvent volume was reduced to 100 μl, and the concentrated extract was acidified. An aliquot was analyzed by HPLC with UV detection (225 nm). Recovery experiments were performed at concentration levels of 1 ppm, 0.1 ppm, and 0.01 ppm. Recovery levels between 65% and 83% with a standard deviation of ±3.75 were achieved at the concentration level of 0.1 ppm. Detection limits between 2 ppb (2,4,6-trichlorophenol) and 2.5 ppb (4-chloro-3-methylphenol) were determined.