Development of a Method for the Determination of Polychlorinated Biphenyls in Microplastics Present in Marine Samples

In this work, a method for the determination of nine polychlorinated biphenyls (PCBs) in three polymer types (polyethylene terephthalate, PET; unplasticized polyvinyl chloride, u-PVC; and low density polyethylene, LDPE) present in marine samples (mussel and marine water) was developed. To optimize extraction methods for PCBs in microplastics, a 24-1 fractional factorial design was applied. Four factors were optimized, namely, sample amount, number of extraction cycles, solvent volume and extraction time. For PET analysis, sample amount was statistically significant for 5 congeners (PCBs 105, 118, 153, 138 and 180), number of extraction cycles and solvent volume were statistically significant only for PCB 101 and extraction time was statistically significant for PCBs 153 and 101. In the case of u-PVC, statistical analysis revealed no relevant variables. For LDPE, sample amount and solvent volume were statistically significant for the lower chlorinated compounds and sample amount was also statistically significant for PCB 52. PCB extracts were analyzed by GC-MS/MS system (triple quadrupole). The separation step of microplastics from marine samples was also tested. For this purpose, studies of behavior of PCBs during the digestion of organic matter were also performed by using KOH and H2O2 solutions. The best results were achieved when 30% H2O2 solution was used. The analytical performance of extraction method demonstrated a broad linear concentration range (R2 < 0.998), in general recoveries around 80–100% and relative standard deviation below 15%. The methodology was applied to the analysis of spiked mussel and seawater samples coming from Galicia coast (NW, Spain).