A field method for the determination of whole blood cholinesterase.

Blood cholinesterase activity is an efficient indicator of exposure to organophosphate insecticides. Field methods, in spite of lacking sensitivity, are important when practical determinations and immediate results are necessary One of the mostly used field methods to assess blood cholinesterase activity is the Lovibond Cholinesterase Field Kit. This paper proposes to substitute the comparator disk of the Lovibond Field Kit with a set of standard solutions that exhibit similar colours. Dilutions of Bromothymol blue, whole blood and acetic acid in different concentrations were used to construct a set of coloured solutions which correspond to different degrees of ChE inhibition. The comparison of acetylcholinesterase activity measured with the two methods showed good agreement and satisfactory reproducibility of results. The use of a standard colored solution kit seems more suitable and manageable for field studies than the Lovibond comparator disk.