An environmental friendly and stable analytical method for the determination of indicator polychlorinated biphenyls (PCBs) in solid and waste oil samples by gas chromatography-electron capture detector (GC-ECD)

This study presents the optimization and comprehensive verification studies of a stable analytical method for the determination of seven indicator polychlorinated biphenyls (PCBs) in solid and waste oil samples by using gas chromatography-electron capture detector (GC-ECD). In extraction method optimization, the maximum efficient and environmentally compatible extraction conditions were obtained at 30 mL hexane:acetone (3:1) use and 1.25 min solvent hold time. In validation studies, this method indicated an excellent linearity from 50 mu g/L to 500 mu g/L since the correlation coefficients higher than 0.9975 for all PCBs. The LOD values varied from 10.1 mu g/ L to 10.3 mu g/L and the LOQ values ranged from 33.7 mu g/L to 45.5 mu g/L. The mean recoveries in soil, sewage sludge and waste oil varied as 85.6-97.7 %, 82.8-91.2 %, and 96.2-108.8 %, respectively. The intra-day precision (RSD, (%) in soil, sewage sludge and waste oil varied as 3.73-6.33 %, 3.72-8.91 %, and 1.37-5.44 %, respectively, whereas the inter-day precision (RSD, (%)) in sewage sludge changed from 2.35 to 9.74 %. In trueness, both results from CRMs (the recovery of PCBs varied 84.3 % to 114.4 %) and PTs (z-scores for indicator PCBs varied from (-0.5 to 1.65) demonstrate that this method possesses well enough and sufficient capability for the rapid, selective, and correct determination of indicator PCBs in soil and waste oil samples. There was no critical ME (recovery varied from 82.6 to 99.5 % in all matrices) and the RSD (%) values for each matrices was below 6 %. In the measurement uncertainty, the expanded uncertainties (mu g/kg) of seven indicator PCBs changed from 3.50 to 4.38. The contributions from the sample preparation (45.19-53.83 %), the calibration curve (20.34-27.04 %) and the repeatability (11.80-18.02 %) were the major sources to the expanded uncertainty. In real samples, eleven sewage sludge, two soil, and twenty-seven waste oil samples had results above the LOQ for at least one indicator PCB.