Quantitation of Polychlorinated Biphenyl Residues by Electron Capture Gas-Liquid Chromatography: Collaborative Study

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Abstract
Ten collaborators quantitated 2 synthetically prepared polychlorinated biphenyl (PCB) mixtures, 2 PCB-fortified milk samples, and an incurred PCB residue in milk and chicken fat. Three electron capture gas-liquid chromatographic (GLC) methods were used for quantitating each unknown PCB against Aroclor reference materials. Two of the methods were existing AOAC total response comparisons and the third was a proposed individual peak comparison. In addition, existing AOAC multiresidue pesticide methodology was employed for determining PCB recovery from whole milk. The average combined recovery of Aroclor 1254 from milk fortified at 1.4 and 2.7 ppm (fat) was approximately 85% (coefficient of variation, 15%) with no significant difference by the methods of quantitation. The incurred PCB residue in milk (as 1254) was determined to be 1.3 (30%), 1.7 (31%), and 1.2 ppm (18%) by total peak height, total area, and individual peak quantitation methods, respectively. In the same order, incurred PCB in chicken fat was determined to be 6.8 (13%), 7.5 (16%), and 5.6 ppm (8%) as 1242, or 6.9 (6%), 5.9 (8%), and 6.3 ppm (8%) as 1248. Total PCB quantitated individually in a 3- and a 4-component chlorobiphenyl mixture, using 1248 as the reference standard, resulted in the following averages of actual amounts present: 3-component—109% (23%), 95% (18%), and 95% (6%); 4-component— 116% (16%), 112% (29%), and 104% (7%), respectively, for total peak height, total area, and individual peak quantitation methods. Both the individual peak quantitation method and the AOAC multi-pesticide methodology have been adopted as official first action methods for PCB.