THE COMPLETE POTENTIOSTAT! The n e w PAR™ Potentiostat/Galvanostat provides more features, m o d e s of operation and flexibility than ever before available.
• ^100 V compliance, 1 A max. • Two independent, internal potential sources • High speed electronic potential switching
• Remote electrometer probe (mounted in signal cable) • 10 Π Π input impedance • Slewing rate: 10V//is
Plug-in modules provide maximum flexibility in readout. Positive feed back IR compensation, high current m e a s u r e m e n t and galvanostatic capabilities up to 1 A are available. The Model 173 replaces a potentiostat. two voltage sources and a current-measuring device. Price of the Model 173 is $2200 including probe. Digital version, $2560. Current r e a d o u t module, $145. I-E converter, $550. 100 raA output ver sion less than $2000. For more data, contact Princeton Applied Research Corp., Box 565, Princeton, N.J. 08540; telephone (609) 452-2111. PRINCETON APPLIED RESEARCH CORPORATION CIRCLE 1 3 7 O N READER SERVICE CARD
New Sulfur Dioxide Recorder Continuous sampling, Ultra portable, Under $1,000 New from Mast, the air monitoring specialist. Measures SO2 within EPA-specified ambient ranges. New selective electrode permits direct and immediate readings of SO2 in air with no significant interferences. Range is continuously variable from 0 to 0.2 ppm/vol. to 0 to 5 ppm/vol. Sensitivity is .005 ppm/vol. Integral strip chart recorder provides permanent data. For full details, send for Bulletin S-l. Ask about Mast low cost, portable Oxidant Monitors, too. The instruments with more than 12 years of field experience.
Report for Analytical Chemists
chemical ionization," at the rela tively high sample concentrations present in combined gas chromatograph—chemical ionization mass spectrometers (56', 57). Preliminary results have been given on chemical ionization reac tions with negative ions t h a t suggest useful applications (58). Although chemical ionization mass spectrometry is associated with the transfer of massive par ticles, the same instrumentation can be used to study charge exchange or electron transfer reactions at high pressures. The majority of charge exchange reactions which have been studied until recently have been studied at relatively low pressures in tandem instruments (59) or with the Cermak source (60). Experi ments have been performed in a high-pressure source with several nonhydrogen-containing gases which produce charge; exchange spectra. The rare gases, N 2 , 0 2 , CO, CO,, K O , C F , , and CCL," have been tried (61). CO appears to be a particularly useful gas, giving spectra which contain both M+ and structurally useful fragment ions. The high-pressure charge exchange spectra of a few pesticides have been obtained and compared with their E I and C I spectra Hi). The charge exchange spectra are more nearly like conventional E I spectra than CI spectra and per haps m a y be easier for mass spectrometrists to interpret. T h e exist ing correlations between structure and E I spectra may be useful in the interpretation of charge exchange spectra. T h e interpretation of chemical ionization spectra will be helped by a knowledge of acidic; solutions, but more structure-spec tra correlations are needed. Acknowledgment
The author is grateful to Noel Einolf and J o h n Miehnowicz for their hell) in preparing this report.
MAST DEVELOPMENT COMPANY 2212 East 12th St., Davenport, la., 52803 (319) 326-0141 AIR MONITOH1NG DIVISION
CIRCLE 109 ON READER SERVICE CARD 40 A
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ANALYTICAL CHEMISTRY, VOL. 4 3 , NO. 13, NOVEMBER
1971
References (1) M. S. B. Munson and F. H. Field, J. Amer. Chcm. Sue, 88, 1621 (1966). (2) J. Miehnowicz and B. Munson, Org. Mas* Spectrum.. 4, 1S1 (1970). (3) J. H. Futrell and L. H. Wo.jeik, Rev. Sci. lustrum., 42, 244 (1971). (4) G. P. Arsonault. "Chemical Ionization Mass Spectrometry." in "Biochemical Applications of Mass Spectrometry," G. R. Waller, Ed.. Wiley-Interscienee. New York, N.Y., 1971 (in press).
