1846
ANALYTICAL CHEMISTRY
that a n 8-minute shaking time is sufficient to pass the sugar through the sieves and mild enough to prevent crystal fracture. Owing to the fact that the plotting is based on the openings of only two sieves, it is necessary t o use sieves which have been carefully standardized. The weighings do not need to be made closer than the nearest gram, but if the screen opening is actually much different from the designated opening, the curve slope changes, and this in turn has a direct effect on the mean aperture and the coefficient of variation values found, and erroneous values will be obtained. When t,he effective opening of a sieve is known, the analysis can be corrected accordingly if there is an appreciable difference between the effective opening and the nominal opening specified by the manufacturer. A complete sieve analysis is contained in the two figures, mean aperture and coefficient of variation. When these values for a sugar are known, the percentage retained on any sieve can be found by using arithmetic probability paper and back-calculating t o establish the curve. The percentage retained on any screen can be taken directly from the reconstructed curve. This is exemplified by Table 111. .4 series of sieves was standardized by the glass sphere method. A random samplc of sugar was then analyzed for mean aperture and coefficient of variation and the curve for the sugar !vas established. The per cent calculated t o be retained on each screen in the series is shown in Column I. Yext, the same sample of sugar was sieved through t,he entire nest and t,he per cent actually found on each sieve is shown in Column 11.
Table 111. Use of Mean Aperture-Coefficient of Variation Data to Determine Complete Screening of a Sugar Screen N o C S Std Series 20 30 40 45 50
ActuaII) Found on Std Screens t c
Calculated
f roin X - C l',
c;;
0 0 3 9 37.8 5s 0 75 0 60 85 8 80 95 4 I00 H i 0 1-10 98 9 Mean aperture 0 0148 Coefficient of variation 32 Naxirnum difference is 2.7r; for X o . 10 screen
ACKNOU'LEDG!M ENT
At the beginning of this work, the Dorr Co. kindl!. supplied a sample of speciaI1y prepared lime rock. LITER.4TURE CITED
(1) Deits, Y.R . , and Carpenter, F. G.. J . Research .\-at[. Bur. Standards, 47, 139-47 (1951). (2) Powers, H. E. C., Intern. Sugar J . , 50, 149-50 (1948). (3) Powers, H. E. C., Tate and Lyle, Ltd., Thames Refinery. London,
England. personal communication.
(4) Roberts, E. J., The Dorr Co., personal communication RI:CEIVFT, for rrvien. October 10, 19,53. iircepted July 23, 19.74.
Ultramicrotechnique for Enzymatic Hydrolysis of Sugars Prior to Chromatogram Analysis WILLIAM L. PORTER
and
NANCY HOBAN
Eastern Utilization Research Branch, Agricultural Research Service,
-
Previously described methods for the enz) matic h) droljsis of sugars on filter paper are not applicable when the hydrolysis is a slow process. An ultramicromethod is given in which 20 to 30 y of sugar can he hydrolyzed in melting point tubes. The hydrolysis products are then analyzed on a papergram.
THE
qualitative analysis of carbohydrates is often greatlv facilitated by examination of the products obtained through enzvme action. The activity or inactivity of specific yeasts toward certain sugars has been used for qualitative and quantitative analysis ( I , 2, 6, 8). Teast fermentation prior to papergram analysis has also been employed ( 3 , 6). Several procedurehave been published for the enzymic treatment of sugars folloTved by resolution and identification of the components of the resulting mixture by means of paper chromatogiaphy. Williams and Bevenue (IO) suggested superimposing a drop of rnzyme solution on a drop of sugar solution alreadv placed on the starting line of a chromatogram. After a ielatively shoit time, the spot was allowed to dry and the chromatogram was developed. From the products identified a more complete picture of the unknown compound could be obtained. This technique, using 20 to 30 of sugar, is an invaluable tool and works extremely well with invertase for such oligosaccharides its sucrose and raffinose. However, during a study of the carbohydrate content of maple sap it was found that the meliblase hydrolysis of melibiose is a murh slower process and that it nas impossible to obtain complete hvdrolysis on paper, as it was impractical to wet the spot for the time required. Since the
U. 5. Department o f Agriculture,
Philadelphia 18, P a .
quantity of samples available for certain identification experiments was extremely limited, an ultramicromethod has been developed based upon techniques used by Schneider ( 7 ) for qualitative organic analysis. I n this method 0.01-ml. samples of solutions, containing 20 to 30 y of sugar, can be enzymatically hydrolyzed in melting point tubes and the entire sample can lie deposited on paper for resolution of the resulting mixture. EQUIPMEYT A Y D hlATERI4LS
Tho usual paper chromatographic equipment. Ilelting point tubes, soft glass, 1 to 2 by 100 mm. S m d l centrifuge. llicroburner. Carbohydrate solution ( 5 mg. per ml.) preserved with tolurnr. 1,;nsyme solutions (10 mg. per ml.) preserved vith t,ilucnr. hIETHOD
Figures 1 and 2 show the steps folloiyed from the treatment of the sample through the application of the material to the paper. The drawings labeled a to h (Figure 1) indicate the steps up to, and including, the incubation period. The drawings labeled i to o (Figure 2) indicate the subsequent steps up to, and including, placement of the hydrol>-zed solutions on the filter paper. Place 1 drop of sugar solution on a microscope slide or in a small test tube. Place a drop of the enzyme solution a t the other end of t,he slide or in another tube. Dip one end of a melting point tube into the sugar solution and allow a volume of 0.01 ml. (about 5 mm., depending upon the tube diameter) to be drawn into the t,ube by capillarity, a. Remove the tube and hold it a t such an angle as to allow the column of solution to flow to about 1 cm.
1847
V O L U M E 2 6 , NO, 11, NOVEMBER 1 9 5 4 DISCUSSION
100rnm.LENGTH ILSmm B O R E
7
E N Z Y M E SOLUTION ( E )
(a)
MICROSCOPE
SLIDE SUGAR \
S
,-.
(b)
S
E
c
-
~
,
e,,-.
PLACE
Figure 1.
.4s diastase required 96 hours to hydrolyze maltose to glucose and the same enzyme did not produce complete hydrolysis of starch in 168 hours, it is evident why it was impossible t o obtain complete hydrolysis directly on filter paper. The technique described herein does produce complete hydrolysis and employs the same ultramicrosamples. The procedure has, therefore, made possible studies of optimum temperature, pH, and sugarenzyme concentrations on limited samples. By placing the hydrolytic tube in boiling water the enzyme can be inactivated and the hydrolysis stopped. The 4-hour maltose sample in Table 1 was inactivat,ed in this manner. Chromatogram analysis of the products showed, in addition t o the expected maltose and glucose, two other oligosaccharides as demonstrated by Pan et al. ( 6 ) .
IN
INCUBATOR
(1)
Steps Required in Preparing Sample for Incubation
'
.p
SCRATCH
a
BREAK -"9
from the opposite end. Dip this clean end of the melting point tube into the enzyme solution until the same volume is taken up, b. Remove the tuhe and, by holding a t the proper angle, cause the two columns of solution t o flow to the tube center, c. JTipe off the cmds of the tuhe and seal the carbohydrate end of the tube iu a microflame, d. Cool and then centrifuge, moving both solutions together into the sealed end, e . Mix the two solutions I)y use of a glass thread drawn from a fine glass rod, J'. Seal the open c~ndof the tube in a microflame, 8 . Centrifuge the contents 1iac.k and forth several times to ensure thorough mixing. (Centrifuging alone does not always give adequate mixing.) Place the sealed tube in an incubator for the predetermined period of time, h. After the inc*ubation period, break the empty end of the tube, placse the tube in a microflamc,, i, and draw- out to a fine threadlike point, j. X a k e a small bead on the t,hreadlike tip to add strength, k . Place the tube in a centrifuge and move the contents to the drawn out end of the tube, I . Scratch the tube a h o u t 1 cm. from the opuosite end and break off, nz. I X n g a pair of tweezers, break off the head on the fine tip, n . Apply the tub, cont>entsto the chromatogram using the t u h its pipet, 0. 1Iultiple drops c m br deposited on one spot if a warni air stream is applied to the paper so as t,o dry it betn-een applications. Rest i,rsults are obtainrd if the solutio,i spreads to a diameter no greater than 8 to 4 mm. Place the paper in a chromatographic2 tank and devrlop. Spray with indicating solution t o Ijiing out the positions of the sugars. Tahle I shows the results obtained using this method for the cAiizymatic h3-drolysis of several carbohydrates. The products indicated b). the chromatogram analyses are presented along with the R, values (referred to glucose). The developing solvent cmployed was isopropyl alcohol-n-but>-1 alcohol-water ( 7 : 1: 2, single phase) as recommended by Gross and Albon (4). The indicating spray \\-as benzidine citrate as developed b\- \Vhite anti \laher ( 9 ) : Solution A, 0.14 gram of benzidine per 100 ml. of n-butyl alcohol; Solution €3, 50'% citric acid monohydrate in water. Just prior to use, mix 3 parts of solution A with one part of POlutioii €3. Spray and heat a t 105" C. for 5 minutes.
(n)
-
p5@=/ BREAK OFF B E A D 7
USE
AS
MICROPIPET
-- - ----
(0)
PAPERGRAM
1 Figure 2. Steps Required in Preparing Tube for Placement of Hydrolyzed Sample on Paper Prior to Development
Table 1. Chromatogram Analyses" of Carbohydrates Enzymatically Hydrolyzed by Ultramicromethod
Carbohydrate Sucrose Raffinose Raffinose Melibiose lfelibiose Maltose Maltose Maltose Starch Starch Starch
Concentration of carbohydrate solution. 3 mg. per nil. Volume for hydrolysis, 0.01 ml. Temperature of incubation, 87' C . T i m e of Resulting Carbohydrate with Hydrolysis, Enzyme Hr. Rob Value 1 Glucose ( 1 , 0 1 ) , fructose (1.15) Invertase c 1Ielibiose ( 0 . 3 7 ) . fructose (1.14) Inrertase 2L Inrertase and Galactose [ 0 . 8 8 ) , glucose ( 1 . 0 0 ) , melibiase 72 fructose ( 1 . 1 5 ) 1Iriihiose 10.37) Invertase 24 In\-ertase and 72 Galactose (0,881, glucose (1.00) nielibiase Diastase T r a w unknowns (0.09, 0.23), mal4 tose (0.50), glucose (1.01) Trace unknown (0.23), maltose Diastase 48 (0.50).glucose (1.00) r;irlrncp ( 1..--, nn) HD ." Diasta-e Unknonns (0.00, 0.09, 0.231, mal24 Diastase tose (0.50), glucose (1.01) Trace unknowns 10.00, 0.09, 0.231, 72 Diastase maltose (0.50). glucose (1.00) Slight traces of unknowns and mallli8 Diastase tose, glucose (1.00)
__
~
a Developing solvent = Isopropyl alcohol: n-butyl alcohol: water (7 : 1 : 2 single phase) ( 4 ) . b R u values agree closely w i t h known carbohydrates run simultaneously. c .411 enzyme concentrations arbitrarily set a t 10 m i , per mi.
1848
ANALYTICAL CHEMISTRY
The procedure, with slight modification, appears to be zpplicable t o enzyme systems other than those reported.
Pan. S. C., Nicholson. L. W., and Kolachov. Paul. Arch. Biochem. Biophus., 42,406 (1953). (6) Porter. W. L., and Fenske, C. S., Jr., J . Assoc. Ofi.A n . Chemists.
(5)
32,714 (1949). LITERATURE CITED
(1) Appling, J . W., Ratliff. E. K., and Wise, L. E., ANAL.Caex.,
19,496 (1947).
(2)
Auernheimer, A. H.. Wickerham, L. J.. and Sohniepp, L. E.,
2bid.,20,876(1948). (31 Govinderrajan. V. S.. J . Sci. 2nd. Resewch (India), 12B, 48 (1 953). (4) Gross, D.. and Albon, N., Andust, 78, 191 (1953).
(7)Sohneider, Frank, "Qualitative Organic Mieroitndysis," New York, John Wiley & Sons,1946. (8) Yoorst, Voorst, F'T.van3Anal'Chim. F. T. van,Anal. Chim. Aeta,2*813 Acta, 2,813 (1948). @) (9) White, J. W., Jr., and Maher, Jes.nnnne, Arch. Bioehem. Bionhys.. 42,360 (1953). (10) Williams, K. T., and Bevenue, A,, Science. Science. 113,582 113, 582 (1951). R ~ ~ m r for i o review April 19. 1954. Accepted July 9, 1954. Preaented before the Division oi Aohlytieal Chemistry st the 126th Meeting of the AMERICAN C n ~ ~ r c n SOCIETY. r. New York, N. Y .
CRYSTALLOGRAPHIC DATA
88.
2,4-Dinitrotoluene
W. C. MCCRONE,Armour Research Foundation of Illinois Institute ofTechnology, Chicago, 111. SIEN-MOO TSANG, Calco Chemical Division, American Cyanamid Co., Bound Brook, N. J.
Contributed by
CIT,
CRYSTAL MORPHOLOGY
NOS Structural Formula for 2,4.-Dinitrotnluene
2.4-DINITROTOLUENE is sliehtlv _ " soluble in ethvl alcohol and diethyl ether at room temperature and easily soluble in less polar solvents such as bemene and chloroform. Good crvstals can he obtained from thymol (Figure 1) or nitrabenaene on a microscope slide.
Tahle I. d
I/Ii
Crystal System. Monoclinic Form and Hahit. Rods and needles elonyated parallel to e showing theprism/ 1101, basal pinaeoid{001),clinopinscoid(010), and orthopinacoid( 1001. AxialRatio. a:b:c = 1.037:1:0.53$. Interfacial Andes (Polar). 100 A 110 = 100'. Beta Angle. IZli'.' X-ItAy DIFFRACTION DATA. (See Table I.) Cell Dimensions. a = 15.83 A.; b = 15.27 A.; c = 8.15 A. Formula Weights per Cell. 8 (8.007 calculated from x-ray ,is+n\ " ' " " a , .
182.13.
Formula Weight.
Prinoipal Lines d
I -b
\ ' 0a L I
w
2
\ b I
erosenpe Slide
Figure 2. Orthographic Projection of Typical Crystal of 2,4-Dinitrotoluene
