NOW a plug-in, finetune, and forget liquid helium transfer and cooling system.
Report
cal chemistry can be seen from Fig ure 3. A large number of the appli cations of mass spectrometry utilize the method in combination with other analytical techniques such as gas chromatography, thermal anal ysis, and also with computers. Prior to 1960 the work horse of an alytical chemistry was the high res olution (3000-10,000 AMU) mass spectrometer. The new trend of combination of mass spectroscopy with other methods resulted in the wide utilization of the medium (500-1000 AMU) resolution mass spectrometer. These medium reso lution instruments were developed by vacuum scientists and made it possible for the various vacuum companies to enter the analytical chemical instrumentation business. The availability of small com puters and the application of mod ern vacuum technology will, how ever, result in a trend to use low resolution (50-150 AMU) and rela tively inexpensive mass spectrom eters in analytical chemistry. These instruments are well known to vac uum scientists as residual gas ana lyzers. Combination Instrumentation
T h i s Cryo-Τίρ® r e f r i g e r a t o r n o w makes it possible to transfer liquid helium, cool a sample and control temperature to 0.01 °K with one com pact, easily-installed system. This device has its own micrometer needle valve and heater for precise adjust ment from 2°K to 300°K. Its six-foot flexible line and miniature refriger ator allow quick installation and cooldown in all analytical instru ments. Your sample can be held in any orientation. Cumbersome set-up and filling of research dewars can be forgotten. Get all the detailed facts on Model LT-3-110 for your partic ular application. Air Products and Chemicals, Inc., Advanced Products Department, Allentown, Pa. 18105. Telephone (2151 395-8355.
Air Products Circle No 5 on Readers' Service Card
Another instrument in which vac uum science contributed to analyti cal chemistry is the vacuum microbalance. The microbalance origi nated in chemistry (9), but was also extensively used and perfected by vacuum scientists (10). Its uti lization in vacuum surface studies is well known. Its utilization in analytical chemistry does not re quire vacuum, but lately it is used more often when a sample is ana lyzed by its changes in a vacuum environment. The vacuum re quirements for such work are not high, analytical chemists use vac uum down to 10~5 torr. If vacuum conditions were improved in ana lytical vacuum microbalance work, it would lead to a combination in strument with greater capabilities. Figure 4 shows a combination in strument which is planned for com pletion at COMSAT Labs. In this analytical system the decomposi tion products of a sample such as a plastic can be analyzed. The anal ysis includes the determination of weight loss by a microbalance, the measurement of decomposition
Coors U.S.A. Filtration Equipment first because
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Coors laboratory filtration equipment is available in many sizes and styles. Made of strong, impervious chemical porcelain, built to take normal laboratory abuse year after year. Easy to clean, nonreactive. Coors filtration equipment comes in 15 styles, 74 sizes, including Buchner funnels, Hirsch funnels, conical funnels, filter cones, Gooch crucibles, Bitumen crucibles, Caldwell crucibles, discs, cups and plates. For micron-size filtration, Coors offers porous-bottom crucibles, Emich micro-filtersticks, and a variety of porous cups, plates and cylinders. See your local laboratory-supply dealer or send for catalog. Coors Porcelain Company, Golden, Colorado 80401 Circle No. 25 on Readers' Service Card
ANALYTICAL CHEMISTRY, VOL. 42, NO. 11, SEPTEMBER 1970 · 31 A
