Cholinesterase measurements with an automated kit.
BACKGROUND
The Test-mate kit determines acetylcholinesterase (AChE, EC 3.1.1.7) and hemoglobin content of a drop of blood, displaying enzyme activities normalized to 25 degrees C. Previous models produced inconsistent results at different temperatures. This report focuses on the current model, ChE 400, and two instruments of a previous OP model.


METHODS
AChE activities were determined by the Ellman assay, using the three kits and a 96-well microplate reader. Temperatures ranged from 10 to 37 degrees C. Fetal bovine serum was the source of AChE.


RESULTS
Normalized activities decreased below 20 degrees C in the ChE model and below 25 degrees C in the OP models. Activities of the same serum sample differed between the three Test-mate kits, ranging from 1.03 to 1.49 micromoles/min/ml. Percent errors were greater than with the microplate reader at all temperatures.


CONCLUSIONS
Neither we nor the manufacturer recommend the current Test-mate model for fieldwork. Nevertheless, there have been field measurements with Test-Mate kits, and we recommend that an enzyme activity standard be run in parallel with their use.
Oliveira
Georgino H
GH
Department of Animal Science, University of California, Davis, California 95616, USA.
Henderson
John D
JD
Wilson
Barry W
BW
D000110:Acetylcholinesterase / Q000097:blood*; D000382:Agricultural Workers' Diseases / Q000175:diagnosis*; D004796:Clinical Enzyme Tests / Q000295:instrumentation*; D006801:Humans; D016273:Occupational Exposure; D010575:Pesticides / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D010575:Pesticides; D000110:Acetylcholinesterase