Investigation of Pharmaceuticals in Environmental Samples Using CE-MS and LC-MS
Detectable limits of pharmaceuticals in wastewater streams resulting from human consumption and excretion could pose a threat to living organisms. A wide variety of pharmaceutical compounds have been detected at low levels (10-400 ng/L) in aquifers, sewage treatment plant effluent, and rivers in several areas of Europe, including Germany, Austria, and England.*Often times the improper disposal of unused or expired pharmaceuticals leach out of landfills and infiltrate water supplies. In addition, pharmacokinetic studies have shown that more than half of all pharmaceutical compounds consumed are excreted unchanged from the body into wastewater. These compounds can potentially survive sewage treatment systems because of their high stability against biological degradation. While the potential effects of these compounds on humans and aquatic organisms are unknown, a method of detection would be the first step in the investigation toward defining the potential risks.
The pharmaceuticals in this study were chosen from a list of the top two hundred prescribed and over the counter drugs in the United States. Compound classes studied include: antihypertensives, analgesics, bronchodilators, antidepressants, anticonvulsants, and antibacterials. Sample cleanup and pre-concentration was performed with solid phase extraction. Current studies have employed liquid chromatography-mass spectrometry (LC-MS) and capillary electrophoresis-mass spectrometry (CE-MS) for the determination of pharmaceuticals in water. Analysis by LC-MS offers both the specificity and detection limits needed in this study.The LC-MS analysis using a triple quadrupole mass spectrometer involves a multiple reaction monitoring (MRM) experiment to selectively detect the most abundant daughter fragment of each selected parent. To confirm the identity of pharmaceuticals in wastewater MS/MS experiments correlate daughter spectra of the compounds in samples to standards. Albuterol, atenolol, metoprolol, propranolol, and fluoxetine have been detected in the Lawrence Wastewater Treatment Plant influent and effluent, Kansas River, and tap water. CE is a good alternative for the separation of charged and polar analytes that may be problematic for LC. CE offers increased efficiency, shorter analysis time, and less solvent waste than LC. Research with CE-MS has focused on the optimal separation and detection conditions in order to achieve good sensitivity and selectivity for the pharmaceuticals. Continuing efforts involve improving the CE-MS interface, sample clean up and preconcentration.
Reference:
*Daughton, C.G. Ternes, T.A. Pharmaceuticals and Personal Care Products in the Environment: Agents of Subtle Change? Environmental Health Perspectives 1999, 107, 907-938
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