Aroclor speciation by unsupervised exploratory analysis of congener proportions in multivariate space: A southern...

Polychlorinated biphenyl (PCB) congeners, sold commercially as different mixtures under the trade name Aroclor in the USA, pose ecological and public health hazards. In the environment, they are monitored as Aroclors for potential source tracking and more accurately as congeners to understand the extent of PCB contamination in total. Because of the subjectivity with which Aroclors are currently identified in samples, striving towards clarity is a focus for analytical chemists. In the current study, the ' Beer-Lambert law' relationship between the analytical response of PCB congeners and their corresponding concentrations is proposed as an exploitable avenue for identifying Aroclors in environmental samples with certainty. For demonstration, direct and unsupervised analysis of peak area-based (not concentration-based) proportions of carefully selected PCB congeners (PCB-8, 18, 28, 44, 52, 66, 87, 101, 105, 110, 118, 128, 138, 153, 170, 180, 183, 187, 195 and 206) in samples, alongside similar proportions in Aroclor 1221, 1248, 1232, 1242, 1254, 1016 and 1260 in a multivariate space identified Aroclor 1254 and likely Aroclor 1260 unambiguously as contaminating PCBs in 29 sediments and fish tissues collected from the Los Angeles/Long Beach harbors and Santa Monica Bay (California, USA). The proposed method eliminates the need to eyeball chromatograms for similarities and removes the expensive and cumbersome step of generating several concentration calibration curves for Aroclor speciation. The method also standardizes congener selection and opens the door towards tracking sources of Aroclors 1254 and 1260 in the southern California bight.