Interlaboratory studies on chlorinated paraffins: Evaluation of different methods for food matrices

Short-chained chlorinated paraffins (SCCP) and medium-chained chlorinated paraffins (MCCPs) are two of the main groups currently used to classify chlorinated paraffins (CPs). Since only SCCPs have been restricted by the Stockholm Convention, a robust but selective analysis with comparable results especially for SCCPs, but also for all other CPs is needed to ensure official controls to enforce future resulting food legislation. Failing that, expansion of the legislation towards total CP or to include MCCPs and other main groups needs to be considered. A survey taken amongst official and private laboratories in the EU and beyond revealed a large variety of methods currently in use or in planning stages for CP analysis. In June 2017, spiked samples of coconut fat were sent to 27 registered participants from 18 countries for an interlaboratory study. In July 2018, lard samples spiked with CPs, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were sent to 13 registered participants from 11 countries. In both cases, more than 55% of participants had a satisfactory overall performance (AZ²<3, σ = 25%). The greatest challenge seemed to be correct quantification of SCCP and MCCP mixtures, hinting at future problems with the through biodegradation much more complex food samples. Of the wide variety of methods being used, GC-MS based methods were favoured. Both HRMS and LRMS methods were able to perform satisfactorily. Identified influencing factors included choice of instrument, choice of standards and data processing strategy. These factors need to be further investigated in future interlaboratory studies.