In-house validation of a simplified method for the determination of PCBs in food and feedingstuffs

This paper comprises a simplified method for the determination of polychlor inated biphenyls (PCBs) in food and feedingstuffs. The method includes a co ld column extraction step, a simple clean-up with concentrated sulfuric aci d, and a final determination of the PCBs using gas chromatography-mass spec trometry (GC/MS). An in-house validation study was performed to establish m ethod performance characteristics such as decision limit, detection capabil ity, trueness and precision of the method. To determine these characteristi cs both certified reference materials and spiked samples were utilized. The decision limit and the detection capability of the individual PCB congener s in food were 2 ng/g and 3 ng/g fat, respectively, while corresponding fig ures for feedingstuffs were 7 ng/g and 9 ng/g fat, respectively. The coeffi cient of variation (CV) varied from 2% to 5% for food on the 10 ng/g fat le vel and from 2% to 6% for feedingstuffs on the 25 ng/g fat level. The recov eries of the individual PCB congeners varied from 88% to 107%, indicating g ood correspondence with internationally recognized criteria for the perform ance characteristics of analytical methods. The robustness of the method wa s investigated by employing a factorial design methodology to determine the influence of six experimental factors on the results of the analysis. This clearly demonstrated that the method is fit for surveillance of PCBs in fo od and feedingstuffs, even though some care has to be taken with the solven t volume during the cold column extraction step as well as the addition of the standard to the sample. Additionally, the investigation clearly demonst rates that in-house validation approaches may be used for determination of the overall performance of analytical methods.