Briefs
ULTRA PURE ACIDS • Double sub-boiling distilled in Quartz. « Produced under CLASS 100 clean room conditions. » Certificate of Analysis. • The world's highest purity acids available commercially. » Ultra cleaned TEFLON acid containers are returnable. Low cost refills.
SEASTAR CHEMICALS (A Division of Seasî-aï· Instruments) MANUFACTURERS Of- ULTRA PURE ACIDS Mil ! J Κί.;Λ[.Λ S1DNFY, 8 C . CANADA V8I. J SI (fi()4) hl>t,-Omt » TFi i-X 0 4 9 7 Ί 2 6
Correspondence Optimized Field-Flow Fractionation System Based on Dual Stream Splitters 945 J. Calvin Giddings, Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 Anal. Chem., 57 {1985) Pulsed Semiconductor Laser Fluorometry for Lifetime Measurements 947 Totaro Imasaka, Akinori Yoshitake, Kaoru Hirata, Yuji Kawabata, and Nobuhiko Ishibashi*, Faculty of Engineering, Kyushu University, Hakozaki, Fukuoka 812, Japan Anal. Chem., 57 (1985) Laser Photodissociation/Tandem Mass Spectrometry of Synthetic Porphyrins: A Structural Probe 949 Elaine K. Fukuda and Joseph E. Campana*, Naval Research Laboratory, Chemistry Division, Washington, D.C. 20375-5000 Anal. Chem., 57 (1985) Unbiased Generalized Standard Addition Method 952 Avraham Lorber, Nuclear Research Centre—Negev, P.O. Box 9001, Beer-Sheva 84190, Israel Anal. Chem., 57 {1985)
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Square Wave Voltammetry at Electrodes Having a Small Dimension 954 John O'Dea, Marek Wojciechowski, and Janet Osteryoung*, Department of Chemistry, State University of New York a t Buffalo, Buffalo, N.Y. 14214, and Koichi Aoki, Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokahama 227, Japan Anal. Chem., 57 (1985)
Aids for Analytical Chemists
GUARANTEED! C18 HPLC COLUMN PROVIDES EFFICIENT SEPARATIONS, American Burdick and Jackson's model OD5 LC Column delivers guaranteed quality and performance for Reverse Phase Liquid Chromatography. Developed to meet B&J internal quality control requirements, it features: • Fully endcapped monomeric C18 bonded phase 5 μΜ spherical silica « Fingertight endfittings included • Rigorous quality control testing • Choice of two column sizes for specific applications. For a free technical bulletin complete with typical applications—contact American Burdick & Jackson, 1953 South Harvey Street, Muskegon, Ml USA 49442. Phone:616 726-3171 American Burdick & Jackson
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504 A · ANALYTICAL CHEMISTRY, VOL. 57, NO. 4, APRIL 1985
Constrained Calibration Curves: A Novel Application of Lagrange Multipliers in Analytical Chemistry 956 J. J. Leary* and Ε. Β. Messick, Department of Chemistry, James Madison University, Harrisonburg, Va. 22807 Anal. Chem., 57 (1985) Microdetermination of Nitrogen in Organic Compounds by the Sodium Fusion-Spectrophotometric Method
958 Ernest J. Breda, E. I. du Pont de Nemours & Company, Inc., Beaumont Works, P.O. Box 3269, Beaumont, Tex. 77704 Anal. Chem., 57 (1985)
Vacuum Actuated High-Vacuum Glass Valve
960
C.A.M. Brenninkmeijer* and MX. Louwers, Louwers Hapert, Hapert, The Netherlands Anal. Chem., 57 (1985)
