Application of an improved steam distillation procedure in residue analysis. Part II. Determination of 2-phenylphenol in citrus fruits by a spectrophotometric method

Abstract

A procedure is described for determining 2-phenylphenol, which is based on the formation of an indophenol dye, by reaction with NN-diethyl-p-phenylenediamine and potassium hexacyanoferrate(III) in alkaline medium. The intensely coloured blue product is extracted from the aqueous reaction mixture with 2-methylpropan-1-ol. Absorbances measured at 660 nm obey Beer's law for concentrations of 2-phenylphenol between 0.20 and 8.00 µg ml_–1.

The extraction of 2-phenylphenol from citrus fruits and the subsequent separation of interfering substances give recoveries ranging between 92.5 and 98.8% and a detection limit of 0.31 p.p.m. is obtained. The procedure is suitable for routine use.