Simultaneous determination of anabolic steroids and β-agonists in milk by QuEChERS and ultra high performance liquid chromatography tandem mass spectrometry.

A simple, accurate and highly sensitive multiresidues method was developed for the determination of 9 anabolic steroids and 16 β-agonists in milk. Target compounds were extracted and separated by a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) method with Primary secondary amine (PSA) and Zinc oxide (ZnO) nanoparticles as adsorbents. The analytes were determined by ultra high performance liquid chromatography coupled to an electro-spray ionization tandem mass spectrometer (UHPLC-MS/MS) operating in negative/positive multiple reaction monitoring mode. The effect of QuEChERS including organic solvent, amount of ZnO nanoparticle was evaluated. Good linearity was obtained for the analytes in the concentration range of 0.1-200μg/L with a correlation coefficients higher than 0.994. Decision limits (CCα) was from 0.007μg/kg-0.1μg/kg, and detection capabilities (CCβ) was in the range of 0.02-0.4μg/kg. The recoveries of these compounds were between 63% and 126% at three fortified levels. Reproducibility represented by RSD was with 10% or less. The method was successfully applied to screening of real milk samples obtained from local markets and confirmation of the suspected target analytes.