A N A L Y T I C A L CHEMISTRY
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It is assumed that errors due to the effect of capillary action on the height of the column are minimized or eliminated by the balanced opposite action in each manometer of the upper and lower menisci. In this respect, the manometric type of instrument may be superior to hydrometers, which may be affected by unknown surface-active substances in the sample-for example, undetermined and unsuspected bile salts in urine. I n the manometers, the glass should be scrupulously clean to avoid unequal surface action. Wetting agents and antiwetting agents may be unsafe because of possible unequal distribution. .in antiwetting agent which was tried gave poor results because of entrapment of bubbles and obviously unequal depression of thr menisci. Because changes in temperature affect the air pressure in the, chamber and hence the heights of the colun~ns,readings should be made promptly. If such change doe; occur, the positions of the columns are easily readjusted by means of thc upper SCI’PW clamp. The lower marks of the manometers do not need to be supported a t the same level, but it is convenient to be able to vie\+ them simultaneously. Inasmuch as equal slant produces small and proportional decreases in column height, it is more important that the manometers be parallel than that they be exactly vertical. LITERATURE CITED
(1) Bauei, S . , “Physical Methods of Organic Chemistry,” 11. 96, Kew York, Interscience Publishers, 1945. (2) Ciochina, Ioan, 2. a ~ ~ aChem.. l. 107, 108-11 (1936). (3) Fisher Scientific Co., Pittsburgh, Pa., Catalogue 90 (1942). (4) Peters, J. P., and Van Slyke, D. D.. “Quantitative Clinical Chemistry.” Vol. 11, Methods, p. 4.7, Baltimore, Williams & Wilkins Co., 1932.
Improved Atomizer for Use in Certain Chromatographic Analysis Procedures. R. T. Morris, Western Regional Research Laboratory, Albany, Calif. SE
of the steps in certain chromatographic procedures
0 involves use of an atomizer to spray a developer solution on -
1
and perhaps some glass company might find it profitable to make a device of this kind available commercially. The model described was designed to fit a standard 125-niI. Erlenmej-er flask with a 1@,/a8 standard-taper joint. Ot,her sizes of flasks or graduated cylinders and joints can be used with allpropriat,e changes in the length of the atomizer column. -411 glass used was borosilicate. The following directions supplement the drawing. Chpital letters and numbers indicate a suggested sequence of construction stel)‘.
A. Heat about 12 mm. of thrx caapillary tubing; bend and draw out to a fine capillary (approximately 0.381 mm. in diameter, 0.015 inch) to form the nozzle. At a point 150 mm. belonthe top of the nozzle, heat the glass and push together to for.in a ridge whicli must, be made small enough to pass through the 12mm. tubing to its final position. This ridge is made to facilitate edirig the capillary to the 12-mm. tube at the lower end of the pray head column. Nest grind down point a, the tip of the nozzle, until i t just permits entrance into the 15-mm. tube which forms the top of the 19/38 ground-glass joint. B. Seal a piece of 12-mm. tubing to the lower end of a 19,.38 standard-taper joint and cut i t 87 mni. from the bottom of the original ground surface (point 1). Measure 150 mm. from the end just cut and a t this point hlow a very small. sharp bulge, but do not break it, 2. This should be approximately 25 mm. above the top of the ground surface. C. After fastening on a brace as shown, insert the capillary tube through the top of the 15-mm. tubing until the nozzle just. seats in the bulge. This brings points b together where a seal and adjustment of the nozzle are made a t the same time. The adjustment, of the nozzle is important. If a bulge is blown and the nozzle fitted into it, just flush with the outside wall of the jacket as shown in the drawing of the nozzle detail, a very fine spray with no large drops will be the end result. When this is done, blow a small hole (5 mm. in diameter) a t c and anneal. Later, when everything else is finished, cut off the capillary that extends a t the loxer end, preferably with a glass-cutting saw. D. By blowing through the hole at c, the dome a t the top can be rounded and the brace from the capillary fixed in place. Kext put, on the tubulation and hooks, and blow the thumb hole in a convenient location a t the t,op, which is used RS a valve to control the air pressure. Anneal ~ ~ 1 1 . E. Just below the joint (on the 12-nini. tubing) blow a small hole and anneal. F. The last step is to grind off the tip, 2, for the nozzle as shon-n in the detail drawing. This opening should be 2 to 2.5 inm. i n diameter.
the paper. Because stronglj acidic solutione are sometimes employed and metallic contamination is undesirable, it is advantageous to use an allNozzle glass atomizer. Several kinds Detail of solutions generally are needed; hcnce it is convenient if an atomizer is available for each solution, so that it i is not necessary to wash a single sprayer between uses. This need led to the development of a sprayer that is reasonably easy for a competent glassbloiver to construct, is compact and exceptionally -I sturdy, and will produce a I 1 fine spray with no large drops. 5 mm. hole/ B e c a u s e a n u m b e r of workers a t this laboratorv contributed suggestions while Apprax. 0.381 mm. opening in t i p this atomizer was being deE LD veloped and because the cp principles are well known, no claim for originality is made. I The usefulness of the device and the widespread interest in chromatography make it seem likely t h a t other workers will be interested,
e1
5 mm.opening for
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s for ng
stopper
