Measurement of acetylcholinesterase in erythrocytes in the field.

We describe here a field method we developed for colorimetry of erythrocytic acetylcholinesterase (EC 3.1.1.7) in capillary blood samples. Three stable, premixed assay reagents and de-ionized water (but no centrifuge or balance) are required. This method, adapted for a microplate format, is essentially that of Ellman et al. (Biochem Pharmacol 1961;7:88-95) as modified by George and Abernethy (Clin Chem 1983;29:365-8). Assays were quantified and corrected for hematocrit by using a battery-powered colorimeter with a silicon carbide (blue) light-emitting-diode source. Advantages over existing field methods include better portability, ruggedness, greater precision, and lower cost per sample.