I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
September, 1942
1117
(8) Michels and Nederbragt, Physica, 3, 569 (1936). (9) Pattee and Brown, IND. ENQ.CHEM., 26,511 (1934). (10) Rose-Innes and Young, Phil. Mag.. [5]47, 353 (1899). (11) Sage, Budenholzer, and Lacey, IND.ENQ. C H ~ M32, . , 1262 (1940). (12) Sage, Hicks, and Lacey, Ibid., 32,1085(1940). (13) Sage and Lacey, Ihid., 34,730(1942). (14) Sage and Lacey, Trans. Am. Inst, Mining Met. Engrs., 136, 136 (1940). (15) Sage, Lacey, and Schaafsma, IND.ENO. CHEM.,27,48(1935). (16) Taylor, Wald, Sage, and Lacey, Oil Gas J., 38 (lo), 46 (1939). (17) Young, Sci. Proc. Roy. Dublin SOC.,12, 374 (1910).
500
IS00
1000
PRESSURE
LR PER
sa.
2000 IN.
FIGURIG 12. FUGACITY OF ?+PENTANE I N T H E COEXISTINU LIQUID AND GAS PHASES OF TEE METHANE-WPENTANE SYSTEM
EFFECT OF LIGHT ON RIBOFLAVIN SOLUTIONS Effect of Sunlight on Reduced and Unreduced Solutions C . M. O’MALLEY AND C. W, SIEVERT
..,.....,
Destruction by sunlight of riboflavin in two extracts of naturally occurring riboflavin and in one solution of the synthetic product were decreased from almost complete destruction to a comparatively small loss, by maintaining the riboflavin in the reduced state with sodium hydrosulfite during exposure to sunlight and reoxidation by air after exposure.
IBOFLAVIN has long been known to be sensitive to light, and this sensitivity has always necessitated careful precautions in the assay for this vitamin. Connor and Straub (1) published data showing the destruction of riboflavin under various conditions. Every investigator has recognized the necessity for protecting riboflavin from light. However, to the authors’ knowledge the protective qualities of reduction have not been investigated. Data are presented in this paper showing that destruction by sunlight can be substantially prevented by converting the vitamin to the reduced state. Two extracts of defatted milk solids and one solution of synthetic riboflavin were prepared in 2 per cent acetic acid and adjusted to a pH of 4.5 with sodium acetate. The solutions for the separate experiments were prepared by diluting
R
American Dry Milk Institute, lnc., Chicago, 111.
a suitable aliquot of the extract to 39 cc. I n the cases where the solutions were to be reduced during exposure, they were made to 38 cc., and 0.5 cc. of hydrosulfite solution (9) was added. All final solutions had a concentration of approximately 0.1 microgram of riboflavin per cc. Of this, 13 CC. were used for the fluorometric readings. All readings were made on a Pfaltz & Bauer fluorophotometer by the procedure of Hodson and Norris (B). Exposure to sunlight was accomplished by placing the solutions in a flat-bottomed round Pyrex dish, 8 cm. in diameter and 4 cm. deep, covered by a Petri dish cover to prevent excessive evaporation. For 30 minutes these units were placed in the sunlight shining through a laboratory window. After exposure, the solutions in which the riboflavin had been reduced were vigorously shaken with access to air to reoxidize the riboflavin. Table I shows that reduced solutions of these extracts, not subjected to sunlight or other treatment and reoxidized by shaking in air, give values in agreement with those of the unreduced solutions. Table I also compares the values of the unreduced solutions before and after exposure to sunlight, and of the solutions before and after exposure where the riboflavin was in the reduced state during exposure. The percentage of the riboflavin remaining after exposure is shown for each case. Table I shows that about 90 per cent of the riboflavin in the unreduced solutions was destroyed by 30-minute exposure to sunlight, but that this destruction was cut to a comparatively small figure when the solutions were treated with hydrosulfite solution before exposure.
1118
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLE I. EFFECTOF SUA-LIGHT ON RIBOFLAVIN CONTENT“
Sample Ext. 1
Before Reduction 25.6 24.6
Av. 2 5 . 1 Ext. 2
26.0 26.4
Q
26.2 26.3
Unreduced Soln., in Sunlight After ”70 of exposure original av. 3.83 3.60
15.3 14 3
25.2
Av. 2 5 . 9
24.8 26.8
S o h . Reduced by Hydrosulfite, in Sunlight After “ib of exposure original av. 24.9 25.4
99 0 101.0
22.0
87.5
2.79 0.50 2.1
120.. 09
21 38 . 08
73 8 9 . 05
Av. 2 5 . 8
8.2
21.4
83.5
21.0 23.5
21.4 21.3
1.59 1.20
7.1 5.4
23.0 20.8
103.0 93.5
Av. 2 2 . 3
Av. 2 1 . 4
Av. 2 5 . 7 S o h . of synthetic riboflavin
After Reduction and Reoxidation, No Sunlight
For convenience the values are 260 times the concentration in terms of micrograms per cc.
Vol. 34, No. 9
flavin is comparatively heat stable, when the solutions are subiected to heat, the volatile reducing agent is driven off, and the riboflavin is reby the air and ‘gain exposed t o destruction by light. I n all such work, therefore, solutions must be kept .from approaching conditions at which the reducing agent is driven off or destroyed. Experiments involving different reducing agents are needed. Further d a t a are now being prepared in this laboratory showing similar relations where the solutions are exposed t o artificial light and diffused daylight. Oxidized
Literature Cited However, reduction of t h e riboflavin solution with an unstable reducing agent such as hydrosulfite solution does not protect t h e solution when heat is applied. Although ribo-
INVENTION OF THE DEVIL
(1) Conner. R. T.,and Straub. G. J., IND.ENG.CHEM., ANAL.ED., 13, 380 (1941). (2) Hodson. A. 2.. and Norris. L.C., J . B ~ O Chem., Z. 131,821(1939).
Artist Unknown
No.
141 in the Berolzheimer series of Alchemical and Historical Reproductions is one of a number of pictures, all showing Berthold Schwartz discovering the explosive power of gunpowder, and all attributing this t o His Satanic Majesty. Our reproduction is from a colored English lithograph of unknown origin. It is not known what artist painted the original from which the lithograph was copied. Obviously the original must have been painted in medieval times. The juxtaposition of the Holy Bible and the Devil is interesting, as is the pleased smirk on the face of the latter. The mortar seems rather large for the purpose; its pestle is of an interesting shape, abandoned many years ago. The Franciscan, Berthold Schwartz, who is also depicted in No. 43 of the series, where there is no implication of “bedevilment”, was a learned alchemist. and is credited with the invention of fire-
arms. D. D. BEROLZHEIMER 50 East 41st Street
New York, N. Y.
The list&of reproductions and directions for obtaining copies appear as follows: 1 to 96, Jauuury, 1939, page 124. 97 to 120 January, 1941, page 114. 121 to 1i2, January,’1942, page 119. An additional reproduction appears each month.
