BRIEFS Sensitivity Enhancements Obtained at High Temperatures in Atmospheric Pressure Ionization Mass Spectrometry 1308 Many compounds such as organosulfur compounds and polyaromatic hydrocarbons that normally have very low sen sitivities in API can be detected at sub-ppb levels with in creased ion-source temperatures. Jan Sunner, Michael G. Ikonomou, and Paul Kebarle*, Depart ment of Chemistry, University of Alberta, Edmonton, Alberta, Can ada T6G2G2 Anal. Chem., 60 (1988) Comparison of Electron Impact, Desorption Chemical Ionization, Field Desorption, and Fast Atom Bombardment Mass Spectra of Nine Monosubstituted Group VI Metal Carbonyls 1314 EI, DCI, and FAB ionization produce molecular ions, M + , and ion fragments; FD forms molecular ions exclusively. B/E linked scans are used to confirm fragmentation using FAB. Richard B. van Breemen*, LeRoy B. Martin, and Anton F. Schreiner, Department of Chemistry, Box 8204, North Carolina State University, Raleigh, NC 27695 Anal. Chem., 60 (1988) Determination of Naphthenic Acids in California Crudes and Refinery Wastewaters by Fluoride Ion Chemical Ionization Mass Spectrometry 1318
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Standard Features D 1-100 AMU Mass Range D Faraday Cup Detector D 100% Front Panel Control D HighResolution CRT Display D Graph or Tabular Data Display D RS232 Computer Interface D 5 χ 10 '2 Torr Minimum Detectable Partial Pressure D Background Subtraction Optional Features D 1-200 AMU Mass Range D Pressure vs Time Display D Graphics Printer For Hard Copy D Electron Multiplier D 5 χ 10"'4 Torr Minimum Detectable Partial Pressure D Sample System For Higher Pressures For literature, contact AMETEK, Thermox Instruments Division, 150 Freeport Road, Pittsburgh, PA 15238. Tel: (412) 828-9040.
AMETEK THERMOX INSTRUMENTS DIVISION
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758 A · ANALYTICAL CHEMISTRY, VOL. 60, NO. 13, JULY 1, 1988
The relative distribution of naphthenic acids in crude oils is determined from the intensities of carboxylate ions pro duced by fluoride ion chemical ionization. Ismet Dzidic*, A. C. Somerville, J. C. Raia, and H. V. Hart, Shell Development Company, Westhollow Research Center, P.O. Box 1380, Houston, TX 77251 Anal. Chem., 60 (1988) Ion Retardation and Collision-Induced Dissociation in the Thermospray Ion Source 1323 Experiments are made with a retarder electrode in thermo spray mass spectrometry. Increasing the retarder potential increases ion intensities and ion fragmentation. F. Aladar Bencsath* and Frank H. Field, The Rockefeller Uni versity, New York, NY 10021 Anal. Chem., 60 (1988) Gradient Reversed-Phase Liquid Chromatography of Proteins on Very Short Columns. Influence of Particle Size on Peak Dispersion 1329 Proteins are separated on 1-cm columns with particles rang ing from 1 to 10 μπι. Phenones (small molecules) and pro teins (large molecules) are compared at different flow rates and different gradients. Maurice Verzele*, Yang-Bo Yang, and Chris Dewaele, Labora tory of Organic Chemistry, State University of Gent, Krijgslaan 281 (S4), B-9000 Gent, Belgium, and Vern Berry, Salem State College, Salem, MA 01970 Anal. Chem., 60 (1988) Optimization of Alumina Selectivity for Tetrachlorodibenzo-/?dioxins and the Isomer-Specific Determination of 2,3,7,8Tetrachlorodibenzo-jv-dioxin 1332 The selectivity of alumina is adjusted using appropriate solvents to obtain optimum separation of TCDDs from PCBs and to isolate 2,3,7,8-TCDD from the other 21 TCDD isomers. Daniel R. Thielen* and Gary Olsen, Occidental Chemical Corpo ration, Technology Center, 2801 Long Road, Grand Island, NY 14072 Anal. Chem., 60 (1988)
