ANALYTICAL CHEMISTRY A p r i l
NEWS
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Papers given at the conference were well attended.^jAttitudes o f the listeners were characterized b y liberal note taking and lively discussions after the papers were given. The Urban Room, used for a large number of the presentations, was on several occasions filled beyond its seating capacity of about 6 0 0 persons
Shifting space allotments for the conference at Pittsburgh's Penn-Sheraton Hotel increased exhibition space b y about 20°/o over last year. Even so, not all companies were able to get all the space they wanted. Proximity of exhibits to the meeting rooms enhanced the value of the conference to visitors
Pittsburgh Conference Stresses Analytical Trends At the exhibition: new instrumentation from here and abroad features greater sensitivity a n d more automatic controls
"PITTSBURGH.
Large attendance
and
·*- a record n u m b e r of exhibits combined t o m a k e t h e P i t t s b u r g h Conference on Analytical Chemistry a n d A p plied Spectroscopy, held here M a r c h 3 t o 7, t h e best in its nine-year history. T h e annual event, sponsored jointly b y t h e Analytical Chemistry G r o u p of A C S ' P i t t s b u r g h Section a n d t h e Spectroscopy Society of Pittsburgh, is a n outgrowth of separate conferences held b y these groups before 1950. About 75 manufacturers a n d distributors of scientific equipment a n d supplies occupied all available space for showing the latest additions t o their lines. M o r e t h a n 2800 analytical
chemists a n d other scientists came to see what t h e companies h a d t o offer. Too, they came to hear of latest developments, as reported in about 150 technical papers. If they expected évidence of dynamic progress, they could not have been disappointed. If they feared a stagnation of t h e profession, they m u s t have been pleasantly surprised. T r e n d s W e l l D e n n e d . T r e n d s in analytical methods a n d in equipment supporting those methods were fairly discernible throughout t h e meeting. As in past years, t h e tendency t o use physical methods for chemical analysis increases, a n d t h e push toward greater automation continues. Also, as in p a s t
years, sensitivity of method continues to increase, a n d sensitivity of equipment moves apace. A new trend is noted, perhaps, in the increasing n u m b e r of items being imported, particularly from West Germ a n y a n d t h e United Kingdom. And an additional, b u t . r a t h e r intangible, trend is a seeming tendency on t h e p a r t of some companies t o strengthen t h e m a r k e t position of products previously introduced. Typically, this might take the form of a new a t t a c h m e n t designed to broaden the scope of an instrument's capabilities. B u t what m a t t e r s whether it b e a new a t t a c h m e n t for a n older instrument or a completely new i n s t r u m e n t ? T h e exposition showed m u c h t h a t is new, much t h a t is interesting. Regarding specific products introduced b y specific companies, m a n y of these will be described in ANALYTICAL C H E M I S TRY'S new p r o d u c t s columns of t h e M a y
issue. W r i g h t ' s A w a r d Address. N o r m a n Wright of D o w Chemical, winner of VOL. 30, NO. 4, APRIL 1958 ·
31A
NEWS
The new fspeecf
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the second annual Spectroscopy Society of Pittsburgh Award, indicated during his award address the extent to which physical methods are now used in chemical analysis. Speaking of the place of infrared spectroscopy among modern methods, he notes t h a t 6 5 % of the papers in the Journal of the American Chemical Society organic section use infrared spectroscopy in some phase of the reported work. H e decries the fact, however, t h a t little or no d a t a of use to the spectroscopist come out of these works. Wright states t h a t N M R spectroscopy and infrared spectroscopy are fundamentally competitive, in t h a t they give almost the same information about a material. New attachments for present infrared equipment extend infrared techniques to the micro range. Also, he adds, newly developed gas cells make possible the analysis of trace quantities in air. Wright also points out t h a t low cost infrared spectrometers should extend use of the technique in qualitative analysis, where it might be used by technicians with small previous experience. Also, improvements t h a t permit higher resolution—such as gratings— make newer instruments of greater value in quantitative organic analysis.
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ANALYTICAL CHEMISTRY
Robert F. Mehl, Dean of Graduate Studies at Carnegie Institute of Technology, was featured speaker at the conference dinner. Mehl, speaker on "Science, Scientists, and Values," stressed the importance of the role of individual and basic research in scientific progress. Universal education, he asserted, should not mean education at the same low level for all. He pointed out the anomaly wherein the world's most competitive social and business system seemingly prefers a socialistic education system
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ANALYTICAL CHEMISTRY
NEWS
Sensitivity Range Extended. Un doubtedly, one of the primary reasons for the trend to greater use of physical methods is the potentially greater sen sitivity that can be obtained. L. S. Birks, U. S. Naval Research Labora tory, speaking on progress in x-ray spectroscopy, discussed sensitivity in terms of weight as well as concentra tion. Depending upon matrix and atomic number, samples in situ may be determined to 10 p.p.m. With a heavy matrix, such as calcium or tungsten, 100 p.p.m. may be deter mined, while the range may go to 1 p.p.m. in the case of a light matrix. Here Birks cited vanadium in gasoline as a practical example. Uranium in solution, concentrated by chemical pre cipitation, he says, may be determined to 0.1 p.p.m. In terms of grams, he says that flat optics place the sensitivity limit at about 10 -5 gram, while curved crystal optics place it at 1CH gram. The elec tron probe analyzer, he adds, pushes the limit down to about lCh13 gram. Accuracy depends largely upon con centration. From a few per cent up ward, this figure would be about 1% of the amount present. Down to 0.1%, the figure would be about 5% of that present. Below 0.1%, accuracy is de pendent on the particular elements and the matrix, and is hard to estimate. Automation in Instruments. The trend toward use of instruments with automatic features is characterized in several papers that were given. Saul Gordon and Clement Campbell, con sulting chemists, described an auto matic recording vacuum thermobal ance. Heating rate, they say, can be automatically varied or held to a con stant temperature. Changes in weight are then recorded electronically, either as a function of temperature at a given heating rate or as a function of time at constant temperature. They say that temperature range goes from am bient to 1000° C. and time intervals can be set from minutes to hours. An automatic colorimetric titrator was described by J. M. Thoburn, M. S. Reynolds, and C. M. Janowski, Central Scientific Co. Reagent is delivered from a motor-driven syringe, for good precision in small volumes, according to the authors. Wave Length Errors Noted. A summary of recent developments in applying spectroscopic techniques to analysis of rare earth mixtures was given by R. N. Kniseley, V. A. Fassel, C. G. Tremmel, and R. J. Jasinski, all of Iowa State College. They discussed purity determinations of heavy rare earths, line misidentifications in rare earth emission spectra, analytical ap plications of flame spectra, and other
NEWS
topics. A most important phase of their work, they feel, lies in the use of band rather than line spectra in flame spectroscopy enabling study of the rare earths as oxides. The authors say that many errors of misidentification have been found in earlier wave length tables. Such errors, they point out, arise from the fact that most of the earlier data were reported in the early 1930's when pure rare earths were not available. They note that, at the present time, about 500 such errors are known. Chemical Microscopy. Use of the
microscope in chemical analysis may become a more attractive possibility, partly due to new developments as discussed by Germain Crossmon, Bausch and Lomb Optical Co. Cross mon says that use of a specially con structed dark-field microscope greatly simplifies use of microscopy in analysis. Its use, he says, makes identification by color possible, as opposed to usual disappearance techniques. Further, he adds, the unknown can actually be photographed in color, providing a permanent record of the analysis itself. Another of the technique's great
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values, according to Crossman, is that it is simple enough to be used by a relatively inexperienced technician in identifying a large number of samples. The author sees immediate practical application of the technique in chem istry, mineralogy, and criminology. He points out, however, that it could also be very useful in administration of food and drug laws and in enforcing customs regulations. The desire to analyze samples rap idly and simply is, of course, a goal that analysts and instrument makers always strive for. M. L. Salmon, Fluo-X-Spec Analytical Laboratory, describes efforts along these lines in the geochemical trace analysis of soil, water, and plant samples by fluorescent x-ray spectrography. Salmon uses a three-position spectrograph with a scintillation detec tor, pulse height analyzer, and a tung sten target x-ray tube. Results appear as a series of singleelement peaks on chart recordings, in parts per million per unit of peak height. Salmon says they are suitable for geochemical prospecting. Samples are taken so as to blanket an area, a fact which leads to accumulation of a large number of samples. One spectrographer, he says, can complete ten times as many samples per day as a chemist. Further, he adds, the cost per sample is about one half to three quarters the cost for chemical methods. Solar X-Ray Studies. Results of rocket measurements of the x-ray region of the solar spectrum were de scribed by Herbert Friedman, U. S. Naval Research Laboratory. A major discovery during the work, says Fried man, is that x-ray emission from the sun is continuous, originating from the corona. Over a solar cycle, he says, x-ray flux varies with coronal activity, as is evi denced by the intensity of corona emis sion lines in the visible. Normally, the spectrum has a maximum at 50 A. and it cuts off at about 20 A. When the corona is active, the short wave length limit may extend to 6 or 7 A. This wave length range is absorbed in the Ε region of the ionosphere at an alti tude of 90 to 140 km. when the sun is overhead. He adds that the flux is great enough to account for almost all Ε region ionization. Friedman says that on rare oc casions of high activity, such as during a solar flare, even shorter x-ray emis sion is observed—down to 2 A.—which ionizes the very lowest border, the D region, of the atmosphere. It appears to Friedman that the emission is ther mal in character, and that it originates from local heating of the flare region to temperatures perhaps as high as 10 million degrees Kelvin.
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ANALYTICAL CHEMISTRY For further information, circle number 37 A on Readers' Service Card, page 83 A
