ANALYTICAL CHEMISTRY
924
Inexpensive Micro Vacuum Desiccator Charles G. Skinner, Biochemical Institute and The Clayton Foundotion for Research, The University of Texas, Austin, Tex. HE efficient removal of excess solvent from recrystallized T s o l i d s requires a different type of desiccant for each class of solvent. For example, it is convenient to have available a vacuum desiccator containing sulfuric acid for pyridine recrystallizations, phosphorus pentoxide for water recrystallizations, and paraffin for petroleurn ether recrystallizations.
sipace and yet inakes availalde five separate desiccants--c.g , phosphorus pentoxide, sulfuric acid, potassium hydroxide, paraffin, and calcium sulfate-for immediate use. Khere compounds must be stored under refrigeration in an anhydrous state, these small desiccators utilize relatively little room in a refrigerator or deep-freeze.
Vial Testing with Manometric Apparatus AI Steyermork and Ruth Reed Koup, Hoffmann-La Roche Inc., Nutley, N J.
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To fit no IO Rubber Stomer
testing with the Van Slyke manometric blood gas has already been described [Steyermark, A , . ISD. ENG.CHEJI., SAL. ED. 17, 191 (1945); Steyermark, A . , “Quantitative Organic lIicroanalysis,” p. 280, Blakiston, Philadelphia, 19511 and used extensively in the laboratories of this company as a means of ohtaining quantitative data for stability studies in which carbon dioxide is a decomposition product. The problem presented itself of performing similar tests on materials for parenteral injections s t o d in rubber-capped vials. llodification of the vessel used for ampoule testing proved satisfactory in the case of vials. Instead of using the plunger to hreak an ampoule, the device \vas modified so that the dcpression of the plunger caused a hypodermic needle t o pierce the rubbcr cap of thc vial, thus connccting its contents with tllc: innnonictric system. Otheririsc, thc procedure is idcritical t’o that used for anipoule testing. Figure 1 givcs the details of csoristruction. MPOULE
A apparatus
bore
iCKYOWLEDGMEYT
Thc authoih ale nidcbted to Henry Niauecki lur pxparatiori of Figure 1.
Having available the usual type of large desiccator containing these desiccants not only is expensive, but uses a good amount of shclf or desk space. Since, in a research laboratory, the amount of material t o be dried is often only a few grams, the author has been using a very simple form of vacuum desiccator, which is inexpensive and occupies relatively little space. It was dcsigned to hold small sinteredglass crucibles or sample bottles. The desiccant is normally placed in the lower section, below the indented tips, and separated from the upper section (containing the sample bottle or crucible) by a small pad of glass wool. A tightly fitted rubher stopper makes an adequate seal for most purpose's and, in contrast to ground-glass stoppers, does not “freeze” 011 prolonged storage. A rack of five desiccators placed in a 3 X 3 X 14 inch wooden block, containing appropriately bored holes, takes up only a small amount of desk
RUBBER SLEW
T$i
GRIND FLAT APPROX I MM. WI DE TO PERMIT GASES TO ESCAPE
SECTION B-B SCALE: $SECTION SHOWING DETAILOF PIERCING ROD CONSTRUCTION
SECTION E-E
SHOWING 2OCC.VIAL IN WSlTlON
Figure 1.
Details of manometric apparatus
