title: Disposable biosensor test for organophosphate and carbamate insecticides in milk.
abstract: A highly sensitive and rapid biosensor test based on disposable screen-printed thick-film electrodes was developed, which is suitable for monitoring organophosphate and carbamate residues in foods of animal origin with increased fat contents such as milk. The wild-type enzyme was combined with three engineered variants of Nippostrongylus brasiliensis acetylcholinesterase (NbAChE), to obtain enhanced sensitivity. The sample pretreatment could be reduced to a minimum. There was no extraction or fat removal necessary. With the biosensor test paraoxon concentrations down to 1 microg/L could be detected in milk. The detection limit for carbaryl was 20 microg/L. Recovery rates for paraoxon and carbaryl in milk samples lay between 89 and 107%. Ten milk samples from local markets were tested both with the biosensor test and with standard chromatographic multiresidue methods. Two milk samples caused AChE inhibition rates of >50%. Accordingly, 4 microg/L tebufenpyrad, 4 microg/L tetraconazole, and 2 microg/L bifenthrin were detected in one of these milk samples. The other milk sample contained 2 microg/L tebufenpyrad.
authors.affiliation: Chemical Engineering Department, Xi'an Jiaotong University, People's Republic of China.
authors.forename: Yaodong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Susanne B
authors.initials: SB
authors.lastname: Muench
authors.forename: Holger
authors.initials: H
authors.lastname: Schulze
authors.forename: Roland
authors.initials: R
authors.lastname: Perz
authors.forename: Bolun
authors.initials: B
authors.lastname: Yang
authors.forename: Rolf D
authors.initials: RD
authors.lastname: Schmid
authors.forename: Till T
authors.initials: TT
authors.lastname: Bachmann
mesh_terms: D000110:Acetylcholinesterase; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002219:Carbamates / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D007306:Insecticides / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D010755:Organophosphates / Q000032:analysis*; D015202:Protein Engineering; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002219:Carbamates; D007306:Insecticides; D010755:Organophosphates; D000110:Acetylcholinesterase