Analysis of polychlorinated alkanes in food by liquid chromatography-tandem mass spectrometry

Polychlorinated alkanes (PCAs), the principal constituents of chlorinated-paraffin technical mixtures, are persistent, bioaccumulative pollutants that raise growing toxicological concern. Due to their complexity, PCA analysis in food remains analytically challenging, predominantly relying on high-resolution mass spectrometry applications. This study aimed to develop and validate a more accessible liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying PCA-C_10-17 in food commodities. Six reversed-phase columns were evaluated during the study, and phenyl-hexyl and biphenyl stationary phases provided superior separation of critical isobaric PCA homologues. Ammonium acetate (5 mM) was used as a mobile phase additive to promote the formation of acetate adducts, enhancing selectivity in MS/MS settings by minimizing the impact of deprotonated species on product-ion spectra. Validation experiments conducted using fortified samples demonstrated satisfactory recoveries (PCA-C_10-13, 88%; PCA-C_14-17, 121%; and PCA-C_10-17, 103%). Comparative analyses using six interlaboratory test materials and a certified fish matrix reference material confirmed the method's accuracy. All z-scores for PCA-C_10-13 were ≤|2|, and only 2 results for PCA-C_14-17 were in the questionable range (|z|= 2-3). In the certified reference material, measured values for PCA-C_10-13 were within the certified range, while those for PCA-C_14-17 were near its lower boundary. The developed method was compared to the conventional high-resolution mass spectrometry, showing a strong agreement between the results of both instrumental setups. These results establish this LC-MS/MS protocol as an accessible and reliable alternative to PCA monitoring within food safety and regulatory frameworks.