A little something for nothing· The Nalgene® Hand-Operated Vac uum Pump puts controllable vac uum in the pal.m of your hand. Weighing less than V2 pound, it at tains a vacuum up to 25 in. Hg with a few easy squeezes of the handleand can hold it for 24 hours! You monitor the exact vacuum on the gauge, calibrated in both centime ters and inches. Pumping rate is 15cc (one cubic inch) per stroke. Will also generate 7 psi positive pressure through tubing connected to the exhaust port. An integral
valve allows releasing or adjusting vacuum without disconnecting the pump from the line. This rugged, versatile vacuum p u m p w i l l have many uses in schools, hospitals, laboratories, and in the field. Specify Nalgene No. 6130. An economy model, identical but without the gauge, is also avail able (Cat. No. 6131). Order from your Lab Supply Dealer. For full details write Dept. 3903, Nalgene Labware Division, Rochester, New York 14602.
Contents
Characterization and Quantitative Measurement of Hydroxyl Groups in Polymer by Fluorine-19 Nuclear Magnetic Resonance of Hexafluoracetone Adducts. F. F.-L. Ho 603 Automated Pregl-Dumas Technique for Determining Total Carbon, Hydrogen, and Nitrogen in Atmospheric Aerosols. R. K. Patterson 605 Analysis of Halogenated Biphenyls by Pulsed Source-Time Resolved Phosphorimetry. C. M. O'Donnell, K. F, Harbaugh, Ft. P. Fisher, and J. D. Winefordner 609 Novel Wet-Digestion Procedure for Trace-Metal Analysis of Coal by Atomic Absorption. A. M. Hartstein, R. W. Freedman, and O. W. Platter 611
Correspondence Influence of pH on the Response of a Cyanide Ion Selective Electrode. Marco Mascini 614 Corrected Equation for the Standard Addition Technique in X-Ray Fluorescence Spectrometric Analysis. J, A. Larson, W. R. Pierson, and M. A. Short 616
Aids for Analytical Chemists Alternate Representation of Mass Spectra for the Spectral Identification Problem (Pattern Recognition). C. F. Bender, H. D. Shepherd, and B. R. Kowalski 617 Rapid Methylation of Micro Amounts of Nonvolatile Acids. M. J. Levitt 618 Design and Evaluation of a Low Cost Recording Spectropolarimeter. S. J. Simon and Κ, Η. Pearson
620
Improved Experimental Technique for Reverse Isotope Dilution Method. W. H. Graham and W. E. Bornak 623 A Simple Off-Line Mass Spectra Digitizer. J. G. Leferink and P. A. Leclerg 625 Metastable Ions in a MS-30 Double Beam Mass Spectrometer. J. M. Miller, J. Ross, J. Rustenburg, and G. L. Wilson 627 Guide for Use of Terms in Reporting Data in Analytical Chemistry 630 Manuscript Requirements
NALGE SYBRON CORPORATION ROCHESTER, NY. 14602, U S.A.
Nalgene® Labware... the safe unbreakables— preferred by professionals. CIRCLE 1 1 7 O N READER SERVICE CARD
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Correction. Resolution by Gas-Liquid Chromatography of Diasteriomers of Five Nonprotein Amino Acids Known to Occur in the Murchison Meteorite. G. E. Pollock 614
