Solenoid-Operated Glass-Mercury Valve for Small Pressure

May 1, 2002 - Solenoid-Operated Glass-Mercury Valve for Small Pressure Differentials. G. S. Martin, and Arthur. Lench. Anal. Chem. , 1959, 31 (10), ...
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Separation of Galactose, Glucose, and lactose in Urine by Paper Chromatography Ahineos J. Philippu, Laboratory of Physiology, University of Athens, Athens, Greece

separatior? of galactose and T glucose in urine by paper chromrrtography without prior desalting or HE

pyridine extraction is difficult because of the similarity in the R , values of these sugars. By use of the wedge kchniquc of paper chromatography [Kitahart, S.. Hiyama, H., Sci. andInd. (Japan)28, 562 (1954)l as well as an original solvent, it was possible to separate these sugars quantitatively.

4 Figure i .

. e

Dimensions of filter paper a.

b. c.

0.4 cm. 5 crn. 15 cm.

d.

18 cm.

e.

4 cm.

67 (1948)]for the separation of galactose and glucose from cerebrospinal fluid. The folio-xing solvent was finally chosen : 1-propanoi: ethyl acetate: water: apicoline = 14:2:4:9 v./v. After drying a t room temperature the filter paper was sprayed with aniline-phosphoric acid in butanol [Bryson, J. L.: Mitche!;. T. J., Nature 167,864 (1951)l and pinced in an oven a t 105” C. for 3 to 5 minutes. A satisfactory separation of galactose. glucose, and lactose required solvent development of about 36 hours. With the above-mentioned technique 5 y of galactose, glucose, and lactose car, be detected. If, however, the urine is expected to contain less than 5 y of reducing sugar pei 0.001 ml., more aliquot is applied on the initial spot, after drying in an air stream. It, is advisable that each application not exceed 0.002 mi.

EXPERIMENTAL

The separation was done oc Whatman filter paper No. 1. One gram each of galactose, glucose, and lactose was dissoived in 100 ml. of centrifuged urine and 0.001 ml.of the solution was applied to the filter paper with a micropipet. When dry, the filter paper waa hung in a glass cylinder, so that its tail dipped into the solvent. Unsatisfactory separat.ion of the sugars was obtained by means of the solvent used by C h a r g d , Levine, and Green [J.Biol. Chem. 175,

Sorenoid-Operafed Glass-Mercury Valve for Small Pressure Differentials G. S. Martin and Arthur tench, Australian Defence Scientific Service, Defence Standards Laboratories, Department of Supply, Maribymong, Victoria, Australia

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the outside of the joint. The joint is formed by simple contact of the flatground end faces of each flange. A negligble area of wax is exposed to the gases in the apparatus and no absorption of oxygen, hydrogen. or carbon monoxide by the wax has beer. detected. The wax is stated (Dus’nInan S., “Vacuum Tec‘hnique,” p. 790, Wile!.. Xew York, 1949) t,c have a vap:ir pressure of less than 10-8 mm. of mercury at room temperature.

in high vacuum systems have never been a wholly satisfactory means of pressure control, principally because of the difficulty of ensuring complete freedom from atmospheric leaks through the grease seal. For work with gas at very low pressure there is always the likelihood of absorption of some gas upon the exposed :ireas of grease. Two alternative devices havr come into use for the control of small pressure differentials in high vacuum systems. TOPCOCKS

The U-type niercurt rutoff vaIvC usually suffers from the dlsadvantagc of a long fragile t pillary gla- connection between the ti-tube and the mercury reservoir. There is also the 99ssibility of atmospheric leakage al the two-way stopcock uwd to control the mercury level. A soIenoid-operawd glass-mercury cutoff valve i s used. Sketches of these apneared i r the literature -scribed in some i,etai! by Emd.4. [ANAI~.‘ LSF. 25, Trier Val:.” 15 PCt IC 1 1 0 ‘

& i T 9

T!h,

d

suitable only for pressure differentials not greater than 2 mm. of mercuq. The authors have developed a nev’ valve of this Lype, showr. diagrammatically in the figure, which overcomes theso !imitations and incorporates a numbe: of imgrovementt. Standard borosilicate giass buttressed flanges flabground on the ends are used, so that the valve can be dismantled for cleaning and yet) easily seaied by applicaticn of a thin line of high-znelting Apiezon Wax W around

A number of sucii valves, made iz two sizes, utilizing flanges 5/’g and inck i n i n t e n d diameter have beepi ir: for about 12 months Tvithout tx’u Thc ioiioning descii:,:i::n refers to I-irich S I Z E . The xdve is norn;s!ix, heid i:, t,l~e open position by the ;enslop cf :t iigh: spnng, .F, which holds the cap, ’.-.: clear of the mercury ir: the 8nl!u.U?+ J. The spring coixsts uf 10 turns 0:’ 24-gage 1;iano WITC wounc; inr, helix incah in tiiamerer. I t is pended from a glass rod. G, fused (,he iugper. rcmovabic part, K , OA’ x - a h ~;,od\.. A g l r i ~rod. a”, conn t1w cap tc, :t glas:i-siisailie:! so?, YOi. 3 ’ , NO.

10, OCTOBER 1955,

* 1743