Chlorinated paraffins (CPs) are complex mixtures of chlorinated alkanes used in a myriad of industrial applications as flame retardant plasticizers and additives. In this study, the distribution and bioaccumulation/biomagnification of short-chain CPs (C10-C13, SCCPs) and medium-chain CPs (C14-C17, MCCPs) were investigated in samples collected between 1999 and 2004 from Lake Ontario and northern Lake Michigan. Total (sigma) SCCPs and sigmaMCCPs concentrations in water from Lake Ontario were 1190 pg/L and 0.9 pg/L (data from 2004 only), respectively. CPs were also detected in invertebrates and fish from both lakes. SCCP predominated in organisms from Lake Michigan with the highest mean concentrations found in lake trout [Salvelinus namaycush, 123 +/- 35 ng/g wet weight (ww)]. In Lake Ontario, MCCPs predominated in most species with the highest levels detected in slimy sculpin (Cottus cognatus, 108 ng/g ww) and rainbow smelt (Osmerus mordax, 109 ng/g ww). Bioaccumulation and biomagnification of CPs was evaluated on an isomer basis (i.e., C10H17Cl5, C10H16Cl6, etc). Log bioaccumulation factors for lake trout (lipid based) ranged from 4.1 to 7.0 for SCCPs and 6.3 to 6.8 for MCCPs. SCCPs and MCCPs were found to biomagnify between prey and predators from both lakes with highest values observed for Diporeia-sculpin (Lake Ontario, C15Cl9 = 43; Lake Michigan, C10Cl5 = 26). Trophic magnification factors for the invertebrates-forage fish-lake trout food webs ranged from 0.41 to 2.4 for SCCPs and from 0.06 to 0.36 for MCCPs. Given the prominence of CPs, particularly in lake waters and in lower food web organisms, further investigation is needed to evaluate the magnitude of their distribution and accumulation/magnification in the Great Lakes environment.

Atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) was applied for the first time to the direct analysis of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in gaseous matrixes without extraction or prior chromatographic separation. Mass spectrometric characteristics of both compounds under APCI conditions and their fragmentation behavior in MS/MS were investigated. Unlike the classical gas chromatography/mass spectrometry (GC/MS), which involves solvent extraction before gas chromatography, the proposed approach prevents contamination from GC system components and provides unambiguous structural assignments. The method performs well achieving good linearity (R(2) > 0.997), low limits of detection (4-6 microg/m(3)), good precision (RSD < 10%) and accuracy (>93%), and a wide dynamic range. Its applicability to real-world samples was evaluated through measurements of D4 and D5 concentrations in air and biogas samples. The high sensitivity, selectivity, and reliability of this method render our approach a good alternative to the commonly used GC/MS method.

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