Method validation and comparison of quantification strategies for analysis of chlorinated paraffins in indoor dust by liquid chromatography and high-resolution mass spectrometry

This paper describes the validation of a method for the simultaneous analysis of short-, medium-, and long-chained chlorinated paraffins (SCCPs, MCCPs, and LCCPs, respectively) in indoor dust by ultrasonic extraction and liquid chromatography quadrupole time-of-flight high-resolution mass spectrometry (LC-QTOF-HRMS). A series of spike and recovery experiments (n = 54) were conducted using CPs with varying carbon-chain lengths, chlorination degree, and concentrations. Technical standard mixtures of the SCCPs, MCCPs, and LCCPs were used to quantify spiking experiments by two commonly used calibration procedures: pattern deconvolution and chlorine-content calibration. The results quantified by pattern deconvolution meet the acceptability limits of the European Union Reference Laboratory (EURL) for all tests with trueness ranging from 72% to 141% and good precision represented by coefficients of variation (CVs) less than 15% in all experiments. The chlorine-content calibration also performed well overall, but on average overestimated concentrations for SCCPs and MCCPs by 32% and 25%, respectively, and did not meet the EURL’s trueness limits in all cases. CVs were below 18% for all results derived from the chlorine-content quantification. The final method was successfully applied to indoor dust samples from offices (n = 4), homes (n = 3), and a vehicle (n = 1) from Melbourne, Australia, with SCCPs (C10-13), MCCPs (C14-17), and LCCPs (C18-20) detected in all samples, up to 100, 240 and 190 μg/g, respectively. A preliminary human exposure assessment suggested that CP intake via dust may constitute a major pathway of exposure for populations in Melbourne, Australia.