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MICRO V TEST TUBE SUPPORT RACKS. You can now magnetically stir in test tubes. Racks are designed to fit snugly on top of the MICRO V. For tubes up to 25 mm dia.
6 x6 MAGNETIC STIRRER • Solid state speed control — 50 to 1700 RPM range · Exclusive dual Alnico-V magnet design prevents "wandering" or "spin-out" of any size bar at top speed. · Stirrer top 6 3 / 8 " square, body 3% "high.
9x9'' MAGNETIC STIRRER Large 9 % " square surface easily accom modates up to 10-gal. carboys. Utmost efficiency insured by solid state speed control and % lb. dual Alnico-V magnet assembly for driving any size stirring bar. Convenient "Load-Mode" switch provides maximum speed resolution for broad range of load conditions.
MONO-MOLD® ^ MAGNETIC STIRRING BARS Newly designed, with more powerful magnets. Completely seamless, no leaks, weak spots or other failures found in conventional bars. Eight sizes, ranging from 7 mm long, 2 mm dia. to 2 % " long, %" dia.
REPORT FOR ANALYTICAL CHEMISTS
were reported generally favorable for most of the techniques. Gravimetry standards in organic chem icals for the concentration of 0.01 % and greater received unanimous ap proval. With respect to inorganic chemicals, approximately 85% re ported favorably ; a somewhat lower favorable percentage was noted for metals and alloys. Availability. For metals and alloys, about 60% of the reports were favorable over the entire con centration range, somewhat slightly less favorable with respect to in organic chemicals. For organic chemicals, the availability was re ported favorable in roughly 75% of the cases. Accuracy. In both organic chem icals and metals and alloys, the percentage of favorable replies was about 80 to 85%. Unanimous sat isfaction was noted for organic chemicals. Cost. In the three major cate gories of application, metals and alloys, inorganic chemicals, and or ganic chemicals, not a single un favorable reply was received con cerning the cost of standard refer ence materials. Indeed, this state ment applies to all reports received —all laboratories were satisfied as to cost. Summary. Since standards for gravimetric analysis have probably received attention over a longer period of time than for any other technique, it is not surprising that the standard reference materials status is in such excellent condition. Perhaps current attention with re spect to gravimetry standards should be directed toward metals and alloy analysis. The signifi cantly large number of replies in dicating usage of gravimetry is indicative of the high reliability of standards for this technique. INFRARED SPECTROMETRY
NEW 1968 CATALOG 1
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ANALYTICAL CHEMISTRY
General Suitability. Approxi mately 75% of the replies for inor ganic chemicals over the entire con centration range were favorable. A somewhat smaller percentage of favorable replies was reported in organic chemicals. This decline was due primarily to only 56% fa
vorable replies for the concentration range of 1-10 ppm. Standard refer ence materials for water analysis received high marks, particularly for the range of 1000 ppm and lower including the concentration range of < 1 ppm. Standards in petro leum analysis, however, were less satisfactory—about 60% favorable replies. For pharmaceuticals, in the concentration range of 10100%, 86% reported favorably. For metals and alloys, only about 50% of the replies were favorable over the entire concentration range. Availability. For most catego ries, there appears to be a need for improved availability of standards. This is demonstrated in particular for water analysis where only ap proximately 20% of the laborato ries reported adequate availability of standards. A somewhat larger percentage was noted for metals and alloys; an even larger percent age for organic and inorganic chem icals but only in rare cases did the percentage of favorable replies ap proach 70%. Accuracy. In most categories, the accuracy of standards for infrared spectrometry was reported unani mously as satisfactory. Notable exceptions, however, were found in organic chemicals—about 70%— and in pharmaceuticals where 67% reported favorably. Cost. Most of the replies with respect to cost were favorable, but not unanimous. About 85%, for example, of the replies for inorganic chemicals were favorable. The most striking example of dissatis faction was observed in water anal ysis where considerably less than 50% of the replies were favorable, particularly at the 10 ppm or lower concentration range. Summary. The number of lab oratories reporting usage of infra red spectrometry was quite large. In general, the suitability of stan dards appears to be rather good, but a considerable disapproval was evi denced with respect to availability and cost of standards in specific ap plications. Since these applications come in areas where infrared spec trometry is the widely used and im portant technique, the need for im proved standards is evident.
