V O L U M E 24, NO. 1 2 , D E C E M B E R 1 9 5 2 2005

100-

90.

BO

D. RIBOSE - R i L.ARABINOSE - A R D-XYLOSE - X Y

WAVE LENGTI4 (MILLIMICRONS)

Spectral Curves of Pentoses Reacted with Figure 1. Anthrone Reagent

0 I I I I ,

,010 10.0

.OOO ,002 ,004 006 .008 SUGAR CONCENTRATION. (PERCENT)

Figure 2. Transmittance Versus Pentose Concentration

Cooling technique used

the tube for about 10 seconds. Heat generated by the mixing raises the temperature to around 95’ C. The test tube is then immediately immersed in an ice bath (0’ C.) for 5 minutes. Be- fore transmittance measurements are taken the tube is brought to room temperature. A blank for the spectral measurements is provided for with 2.00 ml. of distilled water in place of the sample. Spectral measurements are made with a Beckman Model DU spectrophotometer.

The solution of anthrone in sulfuric acid darkens noticeably after a day’s standing, so a fresh solution is prepared each day and allowed to stand about 4 hours to ensure color stability.

DISCUSSION OF RESULTS

Solutions of the three pentoses a t 0.010% concentration, when reacted with 0.05% anthrone in sulfuric acid and allowed to cool a t room temperature for 5 minutes, give spectral curves with no pronounced minimum a t 620 mp characteristic of the blue-green color. These solutions after standing hot have gone over to the amber color (Figure 1). If, however, the tubes are cooled immedi- ately after mixing, the minimum a t 620 mp is observed.

Using the cooling technique, when the per cent transmittance (on a logarithmic scale) is plotted against the concentration (0.001 to 0.010%) a t 620 mp, straight lines are obtained for all three pentoses, thus showing that Beer’s IaTY is obeyed, and making the technique suitable for quantitative analysis (Figure 2).

The transmittances for the various concentrations used have been shown to be constant-45 minutes for D-xylose, 7 5 minutes for L-arabinose, and 90 minutes for o-ribose. If measurements are made within these limits no color instability will be noticeable.

CONCLUSIONS

The use of the anthrone reagent, previously shown to be suit- able for the quantitative determination of hexoses, has been extended to the quantitative determination of pentoses by em- ploying a simple modification of operating technique.

Hexoses will interfere if they are present, so the operating conditions as they now stand apply only to pentose sugars.

ACKNOWLEDGMENT

The author wishes to thank the Masonite Corp., and especially Robert 11. Boehm for permission to publish this material.

LITERATURE CITED

(1) Dreywood, R., IND. ENG. CHEM., A N ~ L . ED., 18, 499 (1946). (2) Morris, D. L., Science, 107,254-5 (1948). (3) Morse, E. E., ANAL. CHEM., 19, 1012-13 (1947). (4) Sattler, L., and Zerban, F. W., Science , 108, 207 (1948). (5) Shnver, E. H., Webb, 11. B., and Smanson, J. IT., Tech. Assoc.

(6) Viles, F. J., and Silverman, L., A X ~ L . CHEM., 21, 960-3 (1949).

RECEI\ E D for review May 8, 1952.

P u l p P a p e r I n d . , 33, 578-86 (1950).

Accepted August 29 , 1952.

C o r r e c t i o n In the summary of one of my papers, reviewed by S. K. Love

[ ~ A L . CHEM., 24, 299 (1952)], the correct text is as follows:

“To 1 ml. of sample add 10 ml. of sulfuric acid and heat just until it fumes. Cool belox 100” C., add 2 ml. of azo dye (0.125 gram of chromotrop 2B in 500 ml. of sulfuric acid), dilute with sulfuric acid to 15 ml., and keep for 30 minutes at 100” C. Cool, and add 0.04 ml. of sodium cobaltinitrite solution. Shake well and keep for 8 hours in darkness. Read color in photometer. Range of application is 0.5 to 25 micrograms of boron per 15 ml.”

HEGEDUS ANDRAS Pazsit-u. 13, Budapest 11, Hungary