A method for analysis of marker persistent organic pollutants in low-volume plasma and serum samples using 96-well plate solid phase extraction

The objective of this study was to develop and validate a 96-well plate solid phase extraction method for analysis of 23 lipophilic persistent organic pollutants (POPs) in low-volume plasma and serum samples which is applicable for biomonitoring and epidemiological studies. The analysis of selected markers for internal exposure: 16 polychlorinated biphenyls (PCBs), 5 organochlorine pesticides (OCPs), octachlorinated dibenzo-p-dioxin (OCDD), and polybrominated diphenylether 47 (BDE 47) was evaluated by comparing two SPE sorbents and GC-HRMS or GC-MS/MS detection. The final method extracted 23 POPs from 150 μL of serum and plasma using a 96-well extraction plate containing 60 mg Oasis HLB sorbent per well prior to GC-HRMS magnetic sector analysis. The extraction method was applied to 40 plasma samples collected for an epidemiological study. The recovery of selected POPs ranged from 31% to 63% (n = 48), and detection limits ranged from 2.2 to 45 pg/mL for PCBs, 4.2 to 167 pg/mL for OCPs, 7.8 pg/mL for OCDD and 6.1 pg/mL for BDE 47. This method showed good precision with relative standard deviations of selected POP concentrations in quality control samples (n = 48) ranging from 11% to 25%. The trueness was determined with standard reference material serum (n = 48) and the deviation from certified values ranged from 1 to 27%. Of the 23 POPs analyzed, 18 were detected in 43% to 100% of plasma samples collected for the epidemiological study. The method showed good robustness with low inter-well plate variation (11-31%) determined by twelve 96-well plate extractions, and can extract 96 samples, including quality controls and procedural blanks in 2-3 days. Comparison with GC-MS/MS analysis showed that similar concentrations (within 0.5% to 30%) of most POPs could be obtained with GC-APCI-MS/MS. Larger deviations were observed for PCB 194 (60%) and trans-nonachlor (43%). The developed method produces accurate concentrations of low-level marker POPs in plasma and serum, providing a suitable high-throughput sample preparation procedure for biomonitoring and epidemiological studies involving large sample size and limited sample volume. GC-HRMS was chosen over GC-MS/MS, however the latter showed promising results, and could be used as an alternative to GC-HRMS analysis for most POPs.