Co-extraction and simultaneous determination of multi-class hydrophobic organic contaminants in marine sediments and biota using GC-EI-MS/MS and LC-ESI-MS/MS

• Development of a multi-residue analytical method using GC-EI-MS/MS and LC-ESI-MS/MS.
• Allows determination of 89 target compounds in a single sediments or biota extract.
• Method detection limits (MDLs) in the low pg/g range.
• Frequent detection of musks, triclosan and HFRs in Singapore's marine environment.

A multi-residue analytical method was developed involving co-extraction and simultaneous determination of 89 hydrophobic organic contaminants (HOCs) in marine sediments and biota using gas chromatography-electron ionization-triple quadrupole mass spectrometry (GC-EI-MS/MS) and liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI-MS/MS). Target analytes include polychlorinated biphenyls (PCBs), pesticides, chlorobenzenes, brominated and chlorinated flame retardants, nitro-aromatic and polycyclic musks, triclosan and methyl triclosan. Spike-recovery experiments showed relative recoveries of analytes were generally between 70% and 130%. Analyses of a sediment standard reference material (SRM 1944) demonstrated recoveries between 80% and 120% for certified concentrations of individual PCBs and pesticides. Method detection limits of individual compounds ranged from 0.1 to 57.1 pg/g dw for sediments and 0.1 to 22.8 pg/g ww for biota. A field survey of sediments and biota from Singapore's marine environment demonstrated the occurrence of polycyclic and nitro-aromatic musks (galaxolide, tonalide, musk ketone, etc.), halogenated flame retardants (syn- and anti-dechlorane plus (DP), α, β and γ-hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), etc.), as well as triclosan and methyl triclosan. Galaxolide exhibited relatively high concentrations, with highest levels in polychaete worms (161.7±72.5 ng/g ww) and clams (546.8±220.3 ng/g ww) from mangroves. Triclosan and methyl triclosan levels were highly correlated in sediments (r2=0.9752), while syn- and anti-DP were strongly correlated in biota (r2=0.9279). anti-DP/syn-DP stereoisomer ratios were typically >1 and ranged between 0.94 and 29.2 in sediments and biota samples. γ-HBCD exhibited the highest concentrations among HBCD isomers in sediments. Conversely, α-HBCD was the dominant HBCD isomer in biota.

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