Development of a screening analytical method for the determination of non-dioxin-like polychlorinated biphenyls in chicken eggs by gaschromatography and electron capture detection.

A sensitive and reproducible screening analytical method is here proposed for the determination of six non dioxin-like polychlorinated biphenyls (NDL-PCBs, congener 28, 52, 101, 138, 153, 180) in chicken eggs based on accelerated solvent extraction (ASE) procedure for the fat extraction and determination, a solid phase extraction (SPE) sample clean-up process, and a gas chromatography - electron capture detection (GC-ECD) analysis. The optimized chromatographic separation, in less than 25 min, returned good responses for the six NDL-PCBs in the range of 2.5-60.0 µg L-1, with correlation coefficients always higher than 0.9995. Instrumental limits of detection were between 0.08-0.35 µg L-1, corresponding to 0.05 and 0.23 ng g-1 fat in the matrix, while method detection limits, calculated on spiked egg samples, ranged from 1.6 to 3.5 ng g-1 fat. The method has been extensively validated in terms of selectivity, sensitivity, recovery, precision, ruggedness and measurement uncertainty, following the European Directives.

Sensitive Screening Method for Determination of Pyrethroids in Chicken Eggs and Various Meat Samples by Gas Chromatography and Electron Capture Detection.

A sensitive and reproducible screening analytical method is described for the determination of six pyrethroids (phenothrin, permethrin, cyfluthrin, cypermethrin, deltamethrin, fenvalerate) in egg and meat samples by gas chromatography and electron capture detection (GC-ECD). A fast cleanup procedure, based on solid-phase extraction has been used, ensuring reduced solvent consumption and time and allowing the simultaneous preparation of multiple sample extracts. Under the optimal chromatographic conditions, an efficient separation was obtained with a total analysis time of less than 60 min, including the extraction-purification steps. Good responses for the six pyrethroids were obtained in a range of 50-500 µg L-1, with linear coefficients higher than 0.9992. Instrumental limits of detection were between 0.22 and 0.63 µg L-1, corresponding to 0.04 and 0.13 µg kg-1 in the matrix. Detection limits in chicken eggs and various meat samples, calculated on spiked samples, were in the range 0.05-0.25 µg kg-1 and 0.07-0.23 µg kg-1, respectively. The validation results confirmed that the proposed GC-ECD method can be used as a reliable screening tool for the determination of pyrethroids in official check analyses. The method was extensively validated following the European directives, demonstrating its conformity in terms of selectivity, sensitivity, recovery, precision, and measurement uncertainty.