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SFE/50
Suprex Supercritical Fluid Extraction reduces extraction time up to 80% for: • • • •
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622 A · ANALYTICAL CHEMISTRY, VOL. 62, NO. 11, JUNE 1, 1990
BRIEFS Composition and Density Effects Using Methanol/Carbon Dioxide in Packed Column Supercritical Fluid Chromatography 1181 The density of methanol/carbon dioxide mixtures is measured at 40 °C. For moderately polar solutes and fixed temperatures, chromatographic retention is found to change more dramatically when fluid composition is changed at constant density than when density is changed at constant composition. Terry A. Berger* and Jerome F. Deye, Hewlett-Packard, P.O. Box 900, Route 41 and Starr Road, Avondale, PA 19311 Chelation Ion Chromatography as a Method for Trace Elemental Analysis in Complex Environmental and Biological Samples 1185 A chelation IC system is described that integrates and automates matrix interference separation, permitting direct analysis of trace elements in complex samples such as aciddigested biological and botanical tissues, seawater, groundwater, and biological fluids. Archava Siriraks and H. M. Kingston", Center for Analytical Chemistry, National Institute of Standards and Technology, Gaithersburg, MD 20899 and J. M. Riviello, Dionex Corporation, Sunnyvale, CA 94086
Correspondence Effect of Ultrasound on the Separation of DNA Fragments in Agarose Gel Electrophoresis 1194 Yinfa Ma and Edward S. Yeung*, Ames Laboratory—USDOE and Department of Chemistry, Iowa State University, Ames, IA 50011
Technical Notes Monitoring of Electrochemical Reactions by Nuclear Magnetic Resonance Spectrometry 1197 Daryl W. Mincey*, Marc J. Popovich, and Patrick J. Faustino, Department of Chemistry, Youngstown State University, Youngstown, OH 44555 and Marilyn M. Hurst and Joseph A. Caruso, Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221
