UPCOMING RESEARCH Structure-Specific Collision-Induced Fragmentations of Ceramides Cationized with Alkali-Metal Ions Complete information about structures of ceramides are obtained from collision-induced decompositions of cation ized species. The detection limit for structural determi nation of N-palmitoyl-DL-sphinganine is 8 pmol. Qinghong Ann and Jeanette Adams*, Department of Chem istry, Emory University, Atlanta, GA 30322 Experimental Determination of the Number of Trapped Ions, Detection Limit, and Dynamic Range in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry The theory and experimental protocol for determining the number of ions that contribute to the detected time do main signal in FT-ICRMS are presented. Patrick A. Limbach, Peter B. Grosshans, and Alan G. Mar shall*, Department of Chemistry, 120 West 18th Avenue, The Ohio State University, Columbus, OH 43210 Self-Assembled Monolayers in Electroanalytical Chemistry: Application of ω-Mercapto Carboxylic Acid Monolayers for the Electrochemical Detection of Dopamine in the Presence of a High Concentration of Ascorbic Acid Self-assembled ω-mercapto carboxylic acid monolayers on gold electrodes are used to introduce an electrochemi cal differentiation between positively charged dopamine and negatively charged ascorbic acid. Franck Malem and Daniel Mandler*, Department of Inor ganic and Analytical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel Heat-Induced Conformational Changes in Proteins Studied by Electrospray Ionization Mass Spectrometry Electrospray ionization MS is used to investigate heatinduced denaturation of proteins a n d to improve t h e spectra of intractable proteins. Urooj A. Mirza, Steven L. Cohen, and Brian T. Chait*, The Rockefeller University, New York, NY 10021 NMR Study of the State of Water in Ion-Selective Electrode Membranes By using variable-temperature NMR, light-scattering centers formed in poly(vinyl chloride)-based ion-selective membranes immersed in water are shown to arise from water droplet formation. Andy D. C. Chan and D. Jed Harrison*, Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
These articles are scheduled to appear in AC RESEARCH in the near future.
pH-Metric log P. 3. Glass Electrode Calibration in Methanol-Water, Applied to pffa Determination of Water-Insoluble Substances A method for calibrating pH electrodes in methanol-wa ter solutions, using a four-parameter equation t h a t re lates the operational pH scale to that based on concentra tion, p c H , is developed a n d applied to d e t e r m i n i n g aqueous pKas of water-insoluble molecules. Alex Avdeef*, John E. A. Comer, and Simon J. Thomson, Sirius Analytical Instruments Ltd., Manor House, Lewes Road, Forest Row, East Sussex, RH18 5AF, United Kingdom Optimization of Waveforms for Pulsed Amperometric Detection of Carbohydrates Based on Pulsed Voltammetry An automated procedure is described for optimization of all variables in PAD waveforms based on pulsed voltam metry a t rotated disk electrodes. William R. LaCourse and Dennis C. Johnson*, Department of Chemistry, Iowa State University, Ames, IA 50011 Determination of Atrazine in Water at Low- and Sub-Parts-per-Trillion Levels by Using Solid-Phase Extraction and Gas Chromatography/High-Resolution Mass Spectrometry Mass profile monitoring is incorporated into a method for trace determination of atrazine. The precision of t h e method is 15% and the accuracy is > 85% a t the 1-pptr level. Zongwei Cai, V. M. Sadagopa Ramanujam, Daryl E. Gib· lin, and Michael L. Gross*, Midwest Center for Mass Spec trometry, Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304 and Roy F. Spalding, Water Center, University of Nebraska, Lincoln, NE 68588-0844 Matrix-Assisted Laser Desorption of Biological Molecules in the Quadrupole Ion Trap Mass Spectrometer Biological molecules are introduced directly into a quad rupole ion trap mass spectrometer via matrix-assisted laser desorption. Single-unit femtomole detection limits and tandem MS structural analysis are demonstrated for small polypeptides. David M. Chambers, Douglas E. Goeringer*, Scott A. McLuckey, and Gary L. Glish, Analytical Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6365 Effects of Buffer pH on Electroosmotic Flow Control by an Applied Radial Voltage for Capillary Zone Electrophoresis Variation of pH for electronic electroosmotic flow control is examined theoretically and experimentally. Control is greatest at low pH and is least a t high pH. Associated band broadening is also examined. Mark A. Hayes, Indu Kheterpal, and Andrew G. Ewing*, Department of Chemistry, Penn State University, 152 Davey Laboratory, University Park, PA 16802
*Corresponding author ANALYTICAL CHEMISTRY, VOL. 64, NO. 24, DECEMBER 15, 1992 · 1151 A
