EQUIPMENT
Ci Ltd. IMPORT AND EXPORT OF CHEMICALS
WARSAW, POLAND
Organic a n d 'inorganic Chemicals With this equipment for emission spectrometry, Bert L . Vallée a n d Keiichiro F u w a (pictured) of H a r v a r d Medical School w o r k e d out applications of cyanogen-oxygen Hames for multiple analysis of heavy trace elements i n small amounts
Pressed Carbon Products
Hotter Flame Boosts Spectrometry
DyesfuÎTS, Pâinîs, Pigments and Lacquers
Vallée and coworkers u s e the flame
Pharmaceuticals
ACS NATIONAL MEETING in a spectrometer that combines photo-
Laboratory Reagents Mining Explosives Essential Oils and Synthetic Aromatics Cosmetics
SAMPLES AND CATALOGUES ON REQUEST For information contact:
COMMERCIAL COUNSELOR POLISH EMBASSY 21 25 LEROY PLACE, N.W. WASHINGTON D.C.
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Cyanogen-oxygen flame extends emission spectrometry to small samples of heavy metals
1959
: AnalyticalJ?hemistry_ One way to make emission spectrometry more effective: Look for a better light-emitting source, for s o u r c e s spark, d.c. arc, or flame—have always been the weakest link in spectroscopic systems, says Bert L. Vallée of H a r v a r d Medical School and Peter Bent Brigham Hospital. In theory, at least, t h e flame looks best; it combines inherent stability and precision with high sensitivity, Vallée notes. Unfortunately, the usual flames d o n ' t have enough energy to excite most of the heavier elements. So Vallée, with coworkers Keiichiro Fuwa and Ralph Thiers, set himself the problem of finding a new fuel, one that would burn at temperatures hot enough to excite even atoms with high excitation potentials. T h e team's answer: a flame of cyanogen and oxygen. It's temperature: 4800° K. T h e y call it "virtually the first n e w spectroscopic flame source in more than 50 years," add that it "promises to broaden the scope of flame spectrometry." Vallée expects the flame c a n b e used in a wide variety of routine analyses for trace metals.
multiplier tubes and a grating spectrograph. With this equipment, they can determine 17 metals u n d e r conditions where conventional flames detect only two. And t h e cyanogen-oxygen flame is particularly well suited for use with small samples, they add. Sensitivity is highest with small aqueous samples because the thermal decomposition of water robs the flame of energy, cooling it until excitation of metals in the sample fails. Burning the sample a t a rate of 0.001 ml. per sec. gives maximum signals. Simultaneous determination of multiple elements takes only 15 sec. O n e determination requires only 0.015 ml. of solution, Vallée told the Division of Analytical Chemistry's Beckman Award Symposium on Chemical Instrumentation. As little as 1 5 X 10~9 grams of sample can be detected and 15 Χ 1 0 - 8 grams can be detected with a precision of ± 2 % . W h a t about safety? Use of cyan ogen poses no special hazards, Vallée points out. It can b e detected by smell at concentrations far below the danger point. And cyanogen's physical, chemical, and explosive properties differ little from those of many other commonly used chemicals. m
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^PRIL
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Analyzing Sulfur Oxides A n a l y z e r eliminates inaccu racies, flow problems in con tinuous sampling
ACS NATIONAL MEETING ^nalyticaHïfiemistfy-
ACS
Award
Beckman Aivard in Chemical
Instrumentation
H. H O W A R D CARY Does the F a r West have a corner on chemical instrumentation experts? T h e trend in winners of the Beckman Award in Chemical Instrumentation might suggest that it does. For the fourth time in as many years, the honor falls to a westerner—H. Howard Cary, president and founder of Applied Physics Corp., Monrovia. Calif. Cary's contributions to analytical chemistry fall primarily in three areas: p H measurement, ultraviolet and infrared spectrophotometry, and Raman spectroscopy. In each he has been responsible for important improvements in commercially available equipment. Cary is a native Southern Caiifornian, born in Los Angeles nearly 5 1 years ago. H e g r a d u a t e d from CaliîOiiiià institute Οχ χ ecxiHOiOgy in the depths of the depression in 1930. His career started in construction work, first as an officer of H . G. Cary Corp., later with Allied Pipe Products. Fortunately for analysts, however, construction held no p e r m a n e n t inter est for Cary. In 1935, when h e joined National Technical Laboratories (now Beckman Instruments) as a develop m e n t engineer, Cary found a place in the field on w h i c h he has left his mark.
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At National he was responsible for de velopment of both laboratory and in dustrial p H meters still widely used. In addition, with \V. P . Baxter, h e de signed a new type of glass p H elec trode, worked out the composition of a glass suitable for electrodes operating up to 100° C , and invented the first glass electrode suitable for use in strongly alkaline solutions. At National, too, Cary helped design the Beckman DU quartz spectropho tometer and the Model IR2 infrared in strument. It represents an important step in the development of modern dual-beam infrared analyzers. τ
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by setting up Applied Physics Corp. T h e new company gave him a chance to continue his efforts in improving spectrophotometric e q u i p m e n t . More recently, Cary and his fellow workers have designed a new photoelectric Ra man spectrograph. O n e instrument specialist describes his work as repre senting "the application of unusual in genuity and scientific insight into the difficult problem of trying to achieve the ultimate in sensitivity and accu racy." Since 1949 Cary also has served as v.p. of Research Instruments Corp.
A simple hatch-type analyzer for sulfur oxides, said to eliminate some of the inaccuracies a n d flow control p r o b lems common in continuous sampling, has been developed at American C y a n amid's Stamford, Conn., research laboiuujiûrs. The new apparatus determines the total amount of sulfur dioxide and sulfur trioxide (as total sulfur oxides) in gas streams. Slight modifications, according to Cyanamid's Raym o n d A. Herrmann, could extend its use to many other gases. The novel feature of the instrument: It converts sulfur trioxide to sulfur d i oxide by passing t h e gas mixture through a furnace at 1050° C. Using air as the carrier gas at oxide concentrations in the range of 5 0 to 1000 p.p.m., conversion is 95f/< ι with nitrogen, con version is even greater. T h e instrument samples a 3-liter vol ume of gas every 15 minutes. T h e sam ple is then b u b h l e d through a meas ured volume of water; conductivity of the solution is a measure of the sulfur oxides present. Converting the trioxide to dioxide has a couple of advantages, Herrmann told the Division of Analytical Chemistrv: • Sulfur dioxide is readily absorbed when bubbled through water, while the trioxide is not (it requires special sol vents ^ • T h e problem of condensation losses with sulfur trioxide is eliminated. Moreover, b y using batch operations, maintaining a constant flow of gas is no problem. Thus both extraction and control procedures are simplified. The apparatus is designed for con tinuous plant u s e . I t could b e used with gases other than sulfur oxides, Herrmann points out, by substituting other liquids than water to dissolve the gas. In addition, physical properties other than conductivity might b e used to measure concentration.
