GC
MN capillaries for separations as sharp as a razor
BRIEFS Preparation and Characteristics of Silica-Based Packings for High-performance Liquid Chromatography Modified with Amino and Carboxyl Groups 2509 Zwitterionic silica-based packings are described for the sep aration of peptides and proteins. The amino and carboxyl groups are chemically, bonded independently of each other, Akira Nomura*, Joseph Yamada, and Kin-ichi Tsunoda, Divi sion of Analytical Chemistry, National Chemical Laboratory for Industry, Tsukuba, Ibaraki 305, Japan Anal. Chem., 60 (1988) Study of the Origin and Mechanism of Band Broadening and Pressure Drop in Centrifugal Countercurrent Chromatography 2513 A model is formulated and equations are derived to explain the efficiency and back-pressure characteristics of centrifu gal countercurrent chromatography. Daniel W. Armstrong*, Gary L. Bertrand, and Alain Berthod, Department of Chemistry, University of Missouri—Rolla, Rolla, MO 65401 Anal. Chem., 60 (1988) Investigation of the Retention Mechanism in Nonionic Micellar Liquid Chromatography Using an Alkylbenzene Homologous Series 2520 Chromatographic data indicate that different retention mechanisms can predominate in micellar liquid chromatog raphy depending on the aqueous solubility of the test solute. A solubility limit equation is demonstrated to adequately describe the retention behavior exhibited by a homologous series of solutes eluted with nonionic micellar mobile phases. Michael F. Borgerding, Frank H. Quina, and Willie L. Hinze*, Department of Chemistry, Wake Forest University, P.O. Box 7486, Winston-Salem, NC 27109, and Jeff Bowermaster and Harold M. McNair, Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 Anal. Chem., 60 (1988)
Ο Standard phases and L-Chirasil-val Ο 10, 25 and 50 m column lengths
Solvent Extraction of Lanthanoid Picrates with Crown Ethers: Preferential Sandwich Complexation and Unique Cation Selectivities 2527
Ο inner diameters from 0.15 to 0.53 mm Ο Up to 5 μηι film thickness with phases OV-1 and SE-54, all other phases up to 2 μηι Ο custom-made capillaries on request
The peak extraction constants are found for samarium with 15-crown-5 (1:2 stoichiometry) and for cerium and praseo dymium with 18-crown-6 (1:1 and 1:2 stoichiometries, re spectively). Kazuharu Nakagawa and Shouhichi Okada, Leather Research Institute of Hyogo Prefecture, 3 Higashikawara, Nozato, Himeji, Hyogo 670, Japan, and Yoshihisa Inoue* and Akira Tai, Basic Research Laboratory, Himeji Institute of Technology, 2167 Shosha, Himeji, Hyogo 671-22, Japan, and Tadao Hakushi, Department of Applied Chemistry, Himeji Institute of Technology, 2167 Shosha, Himeji, Hyogo 671-22, Japan Anal. Chem., 60 (1988) Selective Detector for Gas Chromatography Based on AdductModulated Semiconductor Photoluminescence 2531
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MACHEREY-NAGEL GmbH & Co. KG · P.O.Box 101352 D-5160 Duren • West Germany · Tel. (0 24 21) 610 71 • Telex 8 33 893 mana d Fax (0 24 21) 6 67 16 Switzerland: MACHEREY-NAGEL AG • P.O.Box 46 · CH-4702 Oensingen Tel. (0 62) 76 20 66 • Telex 9 82 908 mnag ch • Fax (0 62) 76 28 64
The photoluminescent intensity of n-CdS and n-CdSe is affected by exposure to volatile Lewis acids and bases, per mitting the construction of a nondestructive, selective detec tor for gas chromatography. George C. Lisensky*, Department of Chemistry, Beloit College, Beloit, WI 53511, and Gerald J. Meyer and Arthur B. Ellis*, Department of Chemistry, University of Wisconsin—Madison, Madison, WI 53706 " Anal. Chem., 60 (1988)
New Telephone number: (O 24 21) 6 98-0 CIRCLE 94 ON READER SERVICE CARD 1264 A · ANALYTICAL CHEMISTRY, VOL. 60, NO. 22, NOVEMBER 15, 1988
