J Chromatogr A. 2012 Dec 4. pii: S0021-9673(12)01682-2. doi: 10.1016/j.chroma.2012.11.003. [Epub ahead of print]
Surface wipe sampling is a frequently used technique for measuring persistent pollutants in residential environments. One characteristic of this form of sampling is the need to extract the entire wipe sample to achieve adequate sensitivity and to ensure representativeness. Most surface wipe methods require collection of multiple samples for related chemicals or chemical classes having similar physiochemical properties. In an effort to analyze a broad suite of pollutants collected from a single surface wipe sample, we developed a new method for the analysis of selected organophosphate and pyrethroid insecticides, pyrethroid transformation products (TPs), bisphenol A (BPA) and polybrominated diphenyl ethers (PBDEs). This is the first time this suite of compounds has been analyzed from a single indoor wipe sample because of the issues uniquely related to these sample types, namely high levels of interfering compounds such as phthalate esters and other residues found in the indoor environment. This new method uses extraction via sonication followed by solvent exchange into hexane, clean-up and liquid/liquid extraction. The extract portion containing insecticides and PBDEs is further purified using solid phase extraction prior to concentration and analysis. The portion containing BPA and TPs is solvent exchanged into ethyl acetate before concentration and derivatization with 99:1 trimethylsilyl 2,2,2-trifluoro-N-(trimethylsilyl)acetimidate:chlorotrimethylsilane. Wipe extract sub-classes were then analyzed by GC/MS in electron impact mode for insecticides, BPA and TPs while negative chemical ionization mode was employed for PBDEs. Method detection limits were <16.4 pg/cm2 for all compounds with most being <5 pg/cm2. Over 400 samples, including QA/QC samples, were analyzed with mean surrogate recoveries ranging from 76 to 95%. The most frequently detected chemicals from our suite were chlorpyrifos, permethrin, bisphenol A, BDE-47, BDE-99 and BDE-100. Permethrin (107 pg/cm2 on floors and 18 pg/cm2 on windows) and bisphenol A (110 pg/cm2 on floors and 6.8 pg/cm2 on windows) had the highest concentrations measured in the wipe samples. Results from the method evaluation and routine sample analysis are presented.