Student Research: Laura Rascón Padilla
MS, Exposure Sciences (ES), 2015
Development of an LC-MS/MS Method for the Detection of Halogenated Furanones in Drinking Water
Halofuranones are chlorine disinfection by-products (DBPs) that have been shown to be direct acting mutagens and are considered potential human carcinogens. These high priority DBPs are among the by-products to be analyzed for the USEPA’s Integrated Disinfection By-product Research Project (Four Lab Study) developed to evaluate the toxicity of the complex mixture of DBPs present in treated water. The traditional method for characterization of halogenated furanones involves liquid-liquid extraction (LLE) and a time intensive derivatization step for gas chromatography analysis. In order to remove the derivatization step and provide a more efficient method to detect halofuranones in the Four Lab Study’s water samples, we coupled a tandem solid phase extraction (SPE) sample preparation step with high performance liquid chromatography (LC) for subsequent mass spectrometry detection (MS/MS). Spiked deionized water samples were processed through tC18 and Osasis (HLB) SPE columns set in train, followed by analyte separation through reverse phase HPLC. A mobile phase linear gradient of 28-45% acetonitrile resulted in optimal peak shape and resolution within 20 minutes. Through UV detection with a diode array detector (DAD), tandem SPE coupled with HPLC yielded recoveries between 76-101% for halofuranones MX, BMX-1, BMX-2, BMX-3, MBA, and MCA, with relative standard deviations of less than 5%. Multiple reaction monitoring Parent-Product ion transitions were detected and optimized for all analytes with direct injection positive electrospray ionization (ESI) MS/MS using Agilent MassHunter Workstation Optimizer Software (version B.06.00). These preliminary results show that halofuranones can be ionized and detected through ESI MS/MS, and that the successful coupling of tandem SPE with HPLC may be paired with ESI MS/MS to generate a more efficient LC-MS/MS method for the characterization of halofuranones.