title: Effect of chlorpyrifos on the inhibition of the enzyme acetylcholinesterase by cross-linking in water-supply samples and milk from dairy cattle.
abstract: A methodology for the determination of chlorpyrifos in water-supply samples and in milk from dairy cattle was developed. An amperometric biosensor was used to inhibit the enzyme acetylcholinesterase (AChE), which was immobilized by the cross-linking method (crosslinks between the enzyme and the sensor). The potential applied, the amount of enzyme to be immobilized and the acetylthiocholine (ACTh) concentration were optimized before calibration and analysis of the samples was performed. The concentration of chlorpyrifos was determined in the range of 1.0×10(-6) M to 5.0×10(-2) M with a detection limit of 5.0×10(-6) M. Spiked water samples showed high recoveries (91.32% and 93.98% for low and high chlorpyrifos levels, respectively), while milk samples exhibited a matrix effect with recoveries of 82.81% and 79.77% for high and low chlorpyrifos levels, respectively. The average concentration of chlorpyrifos in the water supply samples (5.11×10(-6) M), determined using the biosensor, was compared using gas chromatography and gave an average value of 3.04×10(-6) M. The results allow it to be concluded that although chromatographic methods are still more exact, biosensors are promising tools for the determination of analytes in the field, as they have a low cost, a reduced analysis time and good reproducibility in the data.
authors.affiliation: University of Antioquia. Laboratory Diagnostics and Pollution Control (GDCON). University Research Headquarters (SIU), Medellín, Colombia. catalinarodriguez@udea.edu.co
authors.forename: Diana
authors.initials: D
authors.lastname: Catalina Rodríguez
authors.forename: Stephanie
authors.initials: S
authors.lastname: Carvajal
authors.forename: Gustavo
authors.initials: G
authors.lastname: Peñuela
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D002138:Calibration; D002417:Cattle; D004390:Chlorpyrifos / Q000032:analysis*; D002800:Cholinesterase Inhibitors / Q000032:analysis; D003432:Cross-Linking Reagents / Q000737:chemistry; D060766:Drinking Water / Q000737:chemistry; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D057075:Enzyme Assays / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D057230:Limit of Detection; D008892:Milk / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D014881:Water Supply / Q000032:analysis*
chemical_list: D002800:Cholinesterase Inhibitors; D003432:Cross-Linking Reagents; D060766:Drinking Water; D014874:Water Pollutants, Chemical; D000110:Acetylcholinesterase; D004390:Chlorpyrifos