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(066) Ultratrace analysis of pharmaceuticals in natural waters using gas chromatography mass spectrometry .
Padma, Tiruponithura*,1, Blumenfeld, Michael1, Roberts, A1, 1 Johns Hopkins University, Whiting School of Engineering, Baltimore, MD, USA
ABSTRACT- Unmetabolized and discarded pharmaceuticals represent a class of potentially hazardous pollutants. Anticonvulsant and antineoplastic drugs merit particular concern by virtue of their high probable environmental concentrations and potential ecotoxic effects. Detection limits for previous gas chromatography mass spectrometric (GC-MS) studies that sought pharmaceutical analytes in natural waters are reported to be in the low ng/L range. To better assess the prevalence of pharmaceuticals in environmental samples using GC-MS techniques, we have pursued several approaches including solid phase extraction (SPE), derivatization with electrophores and large volume injection techniques. We have investigated three derivatization approaches using PFBBr: a novel biphasic method, a monophasic method developed by Walle (1975), and one based on previous approaches used by Ham et al. (1999) and Kikuchi et al. (2001). The latter was selected for additional modification and optimization. SPE using the OASIS HLB sorbent (Waters Corporation), followed by derivatization with pentafluorobenzyl bromide (PFBBr) yeilded detection limits substantially below 1 ng/L (ranging from 5 to 0.5 pg on column) for 5-fluorouracil, phenytoin, primidone, valproic acid, phenobarbital and secobarbital. Detector response was linear in the electron impact mode, and relative standard deviations ranged from 15 to 8 % for the pharmaceuticals. PFBBr derivatives are also amenable to gas chromatography with electron capture detection as well as to negative chemical ionization GC-MS, which should result in further improvements in sensitivity. Current efforts are directed towards quantitation of these analytes in field samples, including hospital wastewater, as well as sewage treatment plant influent and effluent samples.
Key words: Pharmaceuticals, Antineoplastics, Anticonvulsants, Gas chromatography
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