Veeco INSTRUMENTS INC

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V e r s a t i l i t y is the big extra value in the Veeco GA-4 Gas Analyzer. There are many extra values in the Veeco GA-4. The biggest is the versatility you get in one unit that you might find only in several other units — some much higher in price. In addition, the GA-4 has many unique features of its own, is field-proven, and highly respected for its performance, reliability, workability, practicality, and scan reproducibility. Call us for more facts. Be tough. Have us prove all our claims about the GA-4. We can.

MULTIPLE SCAN MODES provide extreme flexibility. Recorder mode uses built-in chart recorder with 5, 10, 20, and 40 minute scans. Single-peak automatically repetitive scanning is easily performed. Scope CONSOLE OR RACK-MOUNTED alternatives. Unique mode provides instant displays, monitors fast-changdesk type control console rides on casters. Rack- ing conditions. Unique scope-recorder mode uses mounted version is compact and functional, w i t h very slow scope sweep to drive recorder for greatly easily replaceable modules. expanded scans. In any mode, entire mass range or any portion thereof is readily scanned.

EXCLUSIVE THREE-DECADE-LINEAR amplitude scale permits exact comparison of partial pressures over a range of 10,000 to 1 without range switching, has the visual advantages of a log scale w i t h the accuracy and readability of a linear scale.

HIGH MASS SCAN shows excellent resolution of GA-4, such that at mass 75, adjacent masses one unit apart are separated almost to baseline (to 1 % of sum of the two peak heights). Mass range is 2 to 300 a.m.u. Separation of masses two mass units apart is possible to mass 300.

NUDE OR CLOSED SOURCE mass spectrometer configurations are available, both bakeable to 400°C. Unique magnet cradle permits removal and replacement of magnet, completely self-aligned, in 30 sec.

SENSITIVITY IS 10-" TORR or better (N 2 equivalent) w i t h standard GA-4 electron multiplier and electrometer. Chart above was taken after 5x10-? torr system was backfilled w i t h neon to 1.1x10 e torr. Neon mass 20 was the main part of the 6x10'9 torr difference. Reading scale w i t h known relative isotope abundance (neon 21/20 as 0.19%/64%) as a check, neon 21 is 1.8x10·" torr. Simply by reading scale, an easily detectable peak at mass 22.5 (a doubly ionized CO2 isotope) is seen to be about 4x10"14 torr. (Neon calibration differences cancel.)

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FAST SCOPE SCANS at ultrahigh vacuum. Here, the five krypton masses are expanded and scanned at 5 msec/div. (10-3 torr; 10 mv/div.) Extremely slow scanning for detail expansion of high mass peaks may also be performed, viewed on scope, and traced on recorder through unique scope-recorder mode.

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INSTRUMENTS

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TERMINAL DRIVE, PLAINVIEW, NEW YORK 11803 Circle No. 201 on Readers' Service Card 76 A

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ANALYTICAL CHEMISTRY

NEW BOOKS tion of Clinical Chemists. The objective is to present tested methods of assay for biological materials, obtained from the human, for use in the routine laboratory or for research applications. At least two laboratories other than that of the submitter have tested each procedure. Procedures are described in detail for bilirubin, ammonia, cholesterol, chloride, glucose, lead, magnesium, methemoglobin, pH, pC0 2 , phenylalanine, phosphatases, proteins, salicylate, urea, and xylose. While none of the procedures are novel in principle, each has been carefully studied and modified so as to give consistent results in the hands of a technician of moderate skill. The format for each method comprises an introduction which, in effect, is a review of the literature, a section on the principle of the method, and a detailed description of the procedure. The discussion which follows includes values obtained in health and disease, the precision and accuracy of the procedure to be expected, and in most cases, its application to the diagnosis of disease. Finally a list of references is appended. In addition to the procedures included, other pertinent material is discussed. An extensive section on the collection and preservation of specimens is included. Another section presents the sources of error in methodology in Clinical Chemistry. The principles behind the AwioAnalyzer system of automation of procedures is presented succinctly. In addition, for the first time in this series, specifications are given for acceptable primary standards. Cholesterol and bilirubin standards are so defined in this volume. It is apparent that the editor and the editorial committee, W. R. Faulkner, S. R. Gambino, R. P. MacDonald, and E. W. Rice have maintained uniformly high standards in the presentation and evaluation of the procedures. The procedures are presented concisely but with careful attention to detail. The discussion of the methodology is sophisticated and directed to the well-trained chemist. The literature is carefully reviewed. For example, there are well over a thousand entries in the author index. The method for phenylalanine, for screening for phenylketonuria is timely. Certain states have recently passed laws making this test compulsory on all newborns. This book is an excellent sourcebook for a wide range of principles and procedures in analytical chemistry. It is, by far, the best in this series to date.