Synthesis and characterization of eight single chain length chlorinated paraffin standards and their use for quantification

Abstract

Rationale: Quantification of chlorinated paraffins (CPs) via gas chromatography coupled with electron capture negative ionization low-resolution mass spectrometry (GC/ECNI-MS) is a very common practice, although the quality of the results has been disputed due to insufficient mass resolution and the strong impact of the degree of chlorination on the GC/ECNI-MS response. Methods:For further tests we synthesized eight single chain length CP standards (C 10 -C 17 ) with chlorine contents between 51.1% and 61.3%. The individual single chain length standards, 1 + 1 mixtures of two chain length standards and self-prepared mixtures of short-chain and medium-chain CPs were quantified by linear regression according to a previously reported method (method 1) as well as by exponential regression (method 2). Results:Concentrations obtained from single chain length CP standards deviated between −74% and 152% from the target value. However, the error became smaller when self-prepared CP mixes with two and four chain lengths were analysed. For short-chain CP (SCCP) mixture analysis, both methods produced good results (<25% deviation from the target value). In the case of medium-chain CP (MCCP) mixtures, however, method 2 (17-34% deviation) was more accurate than method 1 (43-52% deviation). Conclusions:Both methods 1 and 2 are fit for GC/ECNI-MS analysis of SCCP mixtures, while the improved method 2 is recommended for quantification of MCCP mixtures.

Transport of chlorinated paraffins (CPs) from baking oven doors into the food

“…A new and unused BO was initially tested to release no CPs during operation by means of wipe tests according to Gallistl et al (2018) . Instead of technical CP mixtures, we chose two self-synthesized single chain CP standards ( Sprengel and Vetter, 2019 , Sprengel et al, 2019 ) for the spiking experiments. Accordingly, cross-contamination from other sources could be easily identified due to the unique chain length distribution.…”

“…C 12 -CPs (44.8%, 49.4%, 51.9%, 59.9% and 64.6% Cl), C 15 -CPs (44.0%, 51.1%, 53.5%, 55.0% and 63.6% Cl) and C 16 -CPs (44.6%, 50.9%, 53.1% and 58.9% Cl) were self-synthesized ( Sprengel and Vetter, 2019 , Sprengel et al, 2019 ). Perdeuterated α-hexachlorocyclohexane (α-PDHCH) was also synthesized in our working group ( Vetter & Luckas, 1995 ).…”

“…The GC was equipped with a 30 m × 0.25 mm i.d., 0.25 µm d f Optima 5 MS column (Macherey-Nagel, Düren, Germany) and the MS was operated in selected ion monitoring (SIM) mode. CP quantification followed the method reported by Reth et al (2005) with modifications described elsewhere ( Sprengel & Vetter, 2019 ). CPs and PCBs were measured in GC/ECNI-MS-SIM mode by monitoring the two most abundant isotope peaks of the [M−Cl] - fragment ion (Table S1).…”

“…C 12 -, C 15 - and C 16 -CPs of different degree of chlorination, respectively (instead of SCCP/MCCP mixtures). CP quantification by means of single chain-length CP standards is expected to negate quantification errors based on non-matching chain length composition ( Sprengel & Vetter, 2019 ). Additional tests on the possible occurrence of chlorinated alkenes (chlorinated olefins, COs) were exemplarily performed by means of additional runs covering the [M−Cl] - ions of the Cl 6 -CPs and Cl 6 -COs as well as Cl 7 -CPs (Table S2).…”

“…The baking good was simulated by placing four portions of coconut fat as food simulant and water (to create a vapor phase) into the BO, which were analyzed after the heating process. Analyses were performed with gas chromatography coupled to electron capture negative ion mass spectrometry (GC/ECNI-MS) in selected ion monitoring (SIM) mode ( Sprengel & Vetter, 2019 ).…”