Figure 3.

Dichlorinated OH-PCB was detected by GC–MS/MS and LC–MS Orbitrap in BA19 from a 1-day-old female donor (donor 2017-3, see Table S1). (A) GC–MS/MS chromatogram with MRM transition (m/z) of 252 → 209 showing a peak corresponding to 4′-9 and/or 4–14 (as methylated derivatives) in the extract from a BA19 sample from this donor. The calibration standard, method blank, and reference standard are shown for comparison. LC–MS Orbitrap analysis of the same brain region from the same donor also showed a single dichlorinated OH-PCB peak, indirectly confirming the presence of 4′-9 and/or4-14 in this brain sample. (B) Chromatograms extracted based on the theoretical accurate mass of the top two high-abundance isotope ions of a dichlorinated OH-PCB (chromatogram in black, [C₁₂H₆OCl₂]⁻, m/z 236.98740, chromatogram in red, [C₁₂H₆OCl³⁷Cl]⁻, m/z 238.98445) show peaks at 7.26 min. (C) Accurate mass of both ions at 7.26 min matched the theoretical accurate mass and isotopic pattern of a dichlorinated compound (1:0.6). The LC–MS Orbitrap analysis was performed in the negative polarity mode, as described in the Supporting Information.