Sub-parts-per-million spectrophotometric determination of phenol and related pesticides using diazotized p-aminoacetophenone

A spectrophotometric determination of phenol based on the coupling with dia zotized p-aminoacetophenone in alkaline medium is described. The dye formed is measured at 475 nm against the reagent blank. Beer's law is obeyed over the concentration range 0.6-6.0 mu g per 25 ml of final solution (0.024-0. 24 ppm). Molar absorptivity and Sandell's sensitivity were found to be 3.13 x 10(5) liters mol(-1) cm(-1) and 0.0003 mu g cm(-2), respectively. The me thod has been applied to the determination of phenol and phenol-liberating pesticides, i.e., carbaryl, propoxur, carbofuran, and fenthion, after their thin-layer chromatographic separation in environmental and biological samp les. The method is free from of interference from various organic compounds and inorganic ions. (C) 1999 Academic Press.