Abstract:

Two interference peaks which generally appeared in company with ¹³C labeled 2,3,7,8-tetrachlorodibenzofuran (¹³C₁₂-2,3,7,8-TCDF) in the same ion channel during dioxin analysis for biological samples were identified using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) and high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS). It was firstly inferred that the interference peaks should be the two isomers of dichlorodiphenyldichloroethylene (DDE), which was a breakdown product of dichlorodiphenyltrichloroethane (DDT), one of the typical organic chlorine pesticides (OCPs). Thereafter, the standard solution of DDE including o,p'-DDE and p,p'-DDE was analyzed for confirmation. By evaluation of the peak separation in HRGC/HRMS, comparison of the GC retention times and ion abundance ratios of the two interference peaks in real samples with the two DDE isomers in standard solution, the interference peaks were finally confirmed as o,p'-DDE and p,p'-DDE in sequence on a DB-5MS column. This study provided valuable information for accurate identification of dioxin compounds during the biological sample analysis.

Key words: biological samples, dichlorodiphenyldichloroethylene (DDE), high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS), high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS), interferences, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)