Development and performance evaluation of an analytical method for the analysis of polychlorinated naphthalenes (PCNs) and polychlorinated biphenyls (PCBs) accumulated in pine needles

Polychlorinated naphthalenes (PCNs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) characterized by their mobility, bioaccumulation potential, and toxicity. This study developed, optimized and validated an analytical method for measuring these compounds using pine needles as passive air samplers. We conducted a comprehensive literature review to assess previous methods and to propose an optimized sampling, preparation, extraction, clean-up, and instrumental analysis protocol. The final method employed ultrasonic extraction and Florisil solid-phase extraction (SPE) for clean-up, followed by gas chromatography–tandem mass spectrometry (GC-MS/MS) for quantification. We obtained high recoveries and excellent precisions. Method detection limits (MDLs) averaged 0.070 and 0.095 ng/g for PCNs and PCBs, respectively. To verify the method's applicability, pine needles from rural and urban areas were collected and analyzed. PCBs were detected in all areas, while PCNs were detected primarily in urban areas. Despite restrictions on the production of PCNs and PCBs, their continued detection suggests ongoing emissions and possibly long-range atmospheric transport. To our knowledge, this is the first study using a SPE-based method to analyze PCNs in pine needles. Overall, the optimized method is a relatively simple and robust approach for measuring environmental levels of PCNs and PCBs.