Development of a polychlorinated biphenyl screening method with 3 μL of blood
In the present study, we developed a method of screening for polychlorinated biphenyls (PCBs) by using 3 μL whole-blood samples accurately metered with a capillary tube on filter paper. Elution from the sample and miniaturization of the clean-up were optimized. The analysis of the target PCB congeners in the samples was demonstrated successfully by high-resolution gas chromatography–high-resolution mass spectrometry. This method will be useful for increasing the number of samples tested and performing high-throughput analyses requiring a minimal sample volume and analysis time. For three predominant PCB peaks (IUPAC #153, #138/158/163/164, and #180/193), the results of our screening method and a conventional method were compared by Deming regression analysis. The results yielded slopes of 0.95 (95% confidence interval; CI, 0.758 to 1.14), 1.15 (0.875 to 1.43) and 1.01 (0.847 to 1.16) which were respectively observed. Then the y-intercepts of −6.93 (−23.18 to 9.33), −15.89 (−35.04 to 3.26) and −8.06 (−18.40 to 2.28) were respectively observed. A correlation coefficient of 0.9625 was observed between the results for the sum of these three peaks obtained by the screening method and the total tri- to deca-CB concentration results obtained by the conventional method. Other analytical aspects, such as limits of detection, contamination of the blanks used in the screening method (including information on the presence of some PCB congeners), and comparison of the concentrations with standard reference materials, are also reported. A larger sample size is required to statistically prove the validity of the new screening method; however, the method appears promising for screening for human PCB exposure by using dried blood spot (DBS) samples.