Evaluation of a polyclonal antiserum to pentachlorothiophenol-acetic acid-KLH immunogen: binding properties and use with heterologous PCP derivatives in ELISA for pentachlorophenol

Abstract

A polyclonal antiserum to pentachlorothiophenol-acetic acid-KLH was generated in sheep and assessed by solid phase ELISA. The assessment procedure included use of double checkerboard analysis in the absence and in the presence of analyte loads, estimation of cross reactivities of chlorophenol pesticides, assessment of the effect of pH, Tween 20, and Thames water matrix. The antiserum was highly specific for pentachlorophenol and enabled minimum detection limits of less than 0.2 ng mL⁻¹ in river water matrix. Particularly important was the significant improvement of assay performance in the absence of Tween 20 and at pH 4 and the very low cross reactivity (less than 0.01%) for other commonly used chlorophenols—2,4,5-trichlorophenol and 2,4,6-trichlorophenol, 2-methyl-4-chlorophenoxyacetic acid, and 2,4-dichlorophenoxy acetic acid. The study re-affirms the importance of the judicious choice of hapten derivatives in the synthesis of immunogens and assay reagents for pentachlorophenol analysis by competitive immunoassays.