期刊
JOURNAL OF CHROMATOGRAPHY A
卷 1216, 期 9, 页码 1503-1510出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.chroma.2008.12.084
关键词
Microchip electrophoresis; Atmospheric aerosol; Inorganic anion; Conductivity detection
资金
- US Department of Energy STTR Phase II [DE-FG02-04ER-86179]
- US Environmental Protection Agency SBIR Phase II Project [EP-D-05-058]
- US National Science Foundation [ATM-0737201]
A sensitive and selective separation of common anionic constituents of atmospheric aerosols, sulfate, nitrate, chloride, and oxalate, is presented using microchip electrophoresis. The optimized separation is achieved in under 1 min and at low background electrolyte ionic strength (2.9 mM) by combining a metal-binding electrolyte anion (17 mM picolinic acid), a sulfate-binding electrolyte cation (19 mM HEPBS), a zwitterionic surfactant with affinity towards weakly solvated anions (19 mM N-tetradecyl,N,N-dimethyl-3-ammonio-1-propansulfonate), and operation in counter-electroosmotic flow (EOF) mode. The separation is performed at pH 4.7, permitting pH manipulation of oxalate's mobility. The majority of low-concentration organic acids are not observed at these conditions, allowing for rapid subsequent injections without the presence of interfering peaks. Because the mobilities of sulfate, nitrate, and oxalate are independently controlled, other minor constituents of aerosols can be analyzed, including nitrite, fluoride, and formate if desired using similar separation conditions. Contact conductivity detection is utilized, and the limit of detection for oxalate (S/N=3) is 180 nM without stacking. Sensitivity can be increased with field-amplified sample stacking by injecting from dilute electrolyte with a detection limit of 19 nM achieved. The high-sensitivity, counter-EOF operation, and short analysis time make this separation well-suited to continuous online monitoring of aerosol composition. (C) 2009 Elsevier B.V. All rights reserved.
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