Determination of organochlorines, polychlorinated biphenyls and polybrominated diphenyl ethers in human hair: Estimation of external and internal exposure

•A novel method was developed for the analysis of OCPs, PCBs and PBDEs in hair.•Acetone was used to extract external chemicals in hair samples.•Formic acid-MAE hydrolysis was used to avoid acid-labile OCPs degradation.•PLS-DA was used to analyze chemical profile between external and internal exposure.•Diet was identified to be plausible primary contributor to internal exposure. A novel method was developed for the analysis of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in human hair samples. External contaminants of hair were extracted with acetone under sonication, while washed hair was further hydrolyzed in formic acid and acetone (1:4, v/v) with microwave assisted extraction (MAE) for internal contaminant measurements. Both internal and external extracts were cleaned up with gel permeation chromatography (GPC) and then solid phase extraction (SPE), before analyzed by a large volume injection-gas chromatography–tandem mass spectrometry (LVI–GC–MS/MS) using triple quadruple mass analyzer. Good linearity (R2⩾0.996) was established within a concentration range between 0.1 and 100ngmL−1 among all target analytes. The method was validated for accuracy, precision and sensitivity. The developed method is intended to be cost effective and robust for the routine human hair analysis of PCBs, PBDEs and OCPs including acid-labile OCPs. The described method has been applied in pilot biomonitoring study and the preliminary data suggested that the contaminant profiles with the use of partial least-squares analysis discriminant analysis (PLA-DA) could be useful in differentiating external and internal exposure.