Enzymatic-spectrophotometric method for determination of cholinesterase activity in whole blood: collaborative study.
Ten collaborating laboratories assayed 4 blind duplicate pairs of whole bovine blood for cholinesterase activity. The 4 sample pairs ranged from normal (100%) to severely organo-phosphorus-inhibited (less than 10%) activity. Collaborators also received commercially available human lyophillized serum as an external control and a chromate solution to evaluate spectrophotometer performance. The Ellman kinetic assay was performed on a 1:1000 dilution of the whole blood in pH 8.0 phosphate buffer. The method monitors the increase in absorbance at 412 nm caused by formation of 5-thio-2-nitrobenzoic acid (yellow reaction product). Repeatability standard deviations (RSDr) ranged from 4.30 to 14.2%; reproducibility standard deviations (RSDR) ranged from 6.99 to 19.3%. The lower limit of detection was estimated to be 0.10 mumole/mL/min. The method has been approved interim official first action by AOAC.
Harlin
K S
KS
University of Illinois, College of Veterinary Medicine, Department of Veterinary Sciences, Urbana 61801.
Ross
P F
PF
D000110:Acetylcholinesterase / Q000097:blood; D002091:Butyrylcholinesterase / Q000097:blood; D002802:Cholinesterases / Q000097:blood*; D006801:Humans; D007202:Indicators and Reagents; D007700:Kinetics; D013056:Spectrophotometry, Ultraviolet
D007202:Indicators and Reagents; D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase; D002802:Cholinesterases