QuEChERS-Based Methodology for the Screening of Alkylphenols and Bisphenol A in Dairy Products Using LC-LTQ/Orbitrap MS

A simple methodology was developed for the determination of four Endocrine Disrupting Chemicals (EDCs) in dairy products. The EDCs included alkylphenols (4-tert-octylphenol, technical nonylphenol isomers, 4-nonylphenol) and bisphenol-A. The methodology consisted of a quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction followed by liquid chromatography (LC) coupled to the hybrid LTQ/Orbitrap mass spectrometer (MS). The high resolution (HR) analysis provided the required selectivity demonstrating excellent sensitivity and enabled the high-mass accuracy of the analytes within short time of analysis, after a chemometric optimization of the instrument parameters. An experimental design was employed for the estimation of the effect of different parameters on the QuEChERS extraction efficiency to obtain the optimum conditions. Method validation proved that analysis exhibited excellent linearity (R2 > 0.9966), low enough precision (0.6 to 13.3%) and recoveries in the range of 91 to 108%. Limits of detection (LOD < 6.5 ng g−1) and quantification (LOQ < 20 ng g−1) as well as matrix effects (ME) were also evaluated. The optimized method was successfully applied to analyze dairy commodities varying in fat content and packaging material including milk, yogurts and infant formulae. Detected concentration levels (MDL-10.4 ng g−1) for bisphenol-A BPA in milk samples resulted in 0.36% of TDI for the medium case (average BPA concentrations) and 1.15% of TDI for the worst case (maximum BPA concentration).