Simple method to determine residual cypermethrin and deltamethrin in bovine milk

摘要

A simple, validated and economic method is described for the determination of deltamethrin and cypermethrin in bovine milk. It is based on simultaneous extraction and clean up on matrix solid-phase dispersion (MSPD) with Celite? using hexane/acetone (7:3 v/v), followed by gas chromatography with electron capture detector (GC-μECD) analysis. Confirmatory analysis was carried out by GC-mass spectrometry (MS). The simultaneous process showed to be efficient for milk samples. Average recoveries from fortified bovine milk samples were in the range of 60 to 81%, with relative standard deviation (RSD) from 9 to 18%. Method limits of quantification (LOQ) were 0.010 μg g-1 for both pyrethroids and limits of detection (LOD) were 0.007 and 0.002 μg g-1 for cypermethrin and deltamethrin, respectively. The main advantage of the proposed method is the reduced number of steps involved, besides being simple, rapid and inexpensive. The method was applied to whole milk samples collected at dairy farms in the municipality of Chapada dos Guimar?es, MT, Brazil. Deltamethrin was not detected in the twenty analyzed samples, and cypermethrin was detected in four samples (20%) at trace levels (< LOQ).