Analysis of phosphorothionate pesticides using a chloroperoxidase pretreatment and acetylcholinesterase biosensor detection.
Acetylcholinesterase (AChE) is responsible for the hydrolysis of acetylcholine in the nervous system. It is inhibited by organophosphate and carbamate pesticides. However, this enzyme is only slightly inhibited by organophosphorothionates, which makes the detection of these pesticides analytically very difficult. A new enzymatic method for the activation and detection of phosphorothionates was developed with the capability to be used directly in food samples without the need of laborious solvent extraction steps. Chloroperoxidase (CPO) from Caldariomyces fumago was combined with tert-butyl hydroperoxide and two halides. Chlorpyrifos and triazophos were completely oxidized. Fenitrothion, methidathion and parathion methyl showed conversion rates between 54 and 61%. Furthermore, the oxidized solution was submitted to an AChE biosensor assay. Chlorpyrifos spiked in organic orange juice was oxidized, where its oxon product was detected in concentrations down to 5 microg/L (final concentration food sample: 25 microg/L). The complete duration of the method takes about 2 h.
Roepcke
Clarisse B S
CB
University of Stuttgart, Institute of Technical Biochemistry, Allmandring 31, 70569 Stuttgart, Germany. itbcbs@itb.uni-stuttgart.de
Muench
Susanne B
SB
Schulze
Holger
H
Bachmann
Till T
TT
Bachmann
Till
T
Schmid
Rolf D
RD
Hauer
Bernhard
B
D000110:Acetylcholinesterase / Q000032:analysis; D015374:Biosensing Techniques / Q000379:methods*; D002711:Chloride Peroxidase / Q000032:analysis; D004800:Enzymes, Immobilized / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D009943:Organophosphorus Compounds / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*
D004800:Enzymes, Immobilized; D009943:Organophosphorus Compounds; D010575:Pesticides; D002711:Chloride Peroxidase; D000110:Acetylcholinesterase