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Chlorinated paraffins (CPs) are high production volume chemicals currently produced and used in higher quantities than any other medium-size polyhalogenated compound (class). In addition, the composition of industrial CP mixtures is highly complex and poorly understood. In this article, we searched in the literature for the beginning of the chlorination of alkanes and how this substance class developed from niche applications to unmatched quantities in various industrial applications. Also, an estimation was made on the theoretical variety of chloroparaffins and the possible complexity of industrial CP mixtures. These data may explain why little is known about CPs although the production volume throughout the industrial generation was virtually always higher than the one of PCBs and has continued to increase after the ban of the latter., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Chlorinated paraffins (CPs) are complex mixtures, which consist of thousands of individual compounds with no dominant representative. Consequently, knowledge on structure and environmental relevance of individual CP congeners is poor. Similarly to the synthesis of individual CPs, the generation of less complex CP mixtures that can be thoroughly analyzed may be used to overcome some drawbacks of the highly complex technical CP mixtures. Here, we present a new synthesis approach to generate such simple CP mixtures by decarboxylation of polyunsaturated fatty acids followed by saturation of the double bonds by chlorination. Specifically, α-linolenic acid (18:3Δ9,12,15) was decarboxylated to heptadecatriene. The resulting raw product was chlorinated with SO 2 Cl 2 . Purification by column chromatography led to a main fraction consisting of four major peaks originating from hexachloroheptadecane (C 17 H 30 Cl 6 ) isomers (∼80% of the total peak area) along with ∼20 low abundant by-products, according to gas chromatography with electron capture negative ion mass spectrometry. In the same way, decarboxylation and subsequent chlorination of other polyunsaturated fatty acids may lead to further simple CP mixtures with other chain lengths. Although these simple CP mixtures cannot fully reflect the various structural features present in technical mixtures they could be beneficial for transformation studies because changes in the CP pattern can easily be noted which is in contrast to technical CP mixtures. Such simple CP mixtures could also be used in toxicity tests which are difficult to perform with technical CP mixtures because of their high complexity., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The determination of chlorinated paraffins (CPs) has posed an intractable challenge in analytical chemistry for over three decades. The combination of an as yet unspecifiable number (tens - hundreds of thousands) of individual congeners in mass produced commercial CP mixtures and the steric interactions between them, contrive to defy efforts to characterise their residual occurrences in environmental compartments, food and human tissues. However, recent advances in instrumentation (mass spectrometric detectors and nuclear magnetic resonance), combined with interlaboratory studies, have allowed a better insight into the nature of the conundrums. These include the variability of results, even between experienced laboratories when there is insufficient matching between analytical standards and occurrence profiles, the poor (or no) response of some instrumentation to some CP congener configurations (multiple terminal chlorines or < four chlorines) and the occurrence of chlorinated olefins in commercial mixtures. The findings illustrate some limitations in the existing set of commercially available standards. These include cross-contamination of some standards (complex CP mixtures), an insufficient number of single chain standards (existing ones do not fully reflect food/biota occurrences), lack of homologue group standards and unsuitability of some configurationally defined CP congeners/labelled standards (poor instrument response and a smaller likelihood of occurrence in commercial mixtures). They also indicate an underestimation in reported occurrences arising from those CPs that are unresponsive during measurement. A more extensive set of standards is suggested and while this might not be a panacea for accurate CP determination, it would reduce the layers of complexity inherent in the analysis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

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 (AZ 2 <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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Chlorinated paraffins (CPs) are complex mixtures of persistent contaminants present throughout the aquatic food web. In this study 122 farmed and 11 wild salmon samples were collected over the course of four years (2014-2017). The ratio of short-chain CP and medium-chain CP and the corresponding homologue patterns were determined by means of gas chromatography (GC) with high resolution, accurate mass Orbitrap mass spectrometry (MS) technology. Characteristic patterns were observed, enabling differentiation between European and non-European (Chilean) samples. Concentration ranges of short-chain CPs (0.97-170 ng/g ww) and medium-chain CPs (1.1-79 ng/g ww) were similarly widespread over three orders of magnitude. Yet, both the mean and median concentrations of MCCPs were usually higher than those of the SCCP. CP levels were generally higher than those of marker polychlorinated biphenyls (PCBs) and hexabromocyclododecanes (HBCDDs). An age- and gender-dependent estimated intake range of 4.6-35 ng/kg bw/week for short and medium-chain CPs via the consumption of salmon was calculated for adults in Germany., (Copyright © 2019 Elsevier Ltd. All rights reserved.)