ANALYTICAL CHEMISTRY
1788
E. Add 10 ml. of 2.070 potassium ferricyanide solution to
all portions and mix immediately. F. Immediately pour 100 ml. of the sample and the 0.2 p.p.m. standard into individual 100-ml. Nessler tubes. If the sample does not show more red color than the standard, consolidate the entire sample portion and put it in a 1-liter separatory funnel. Put the blank and the 0.04 p.p.m. standard in 1-liter separatory funnels. Extract these solutions serially with 15-, lo-, and 5-ml. portions of chloroform. Combine the extracts and make them up to 25 ml. with chloroform. Filter the extracts or high before volume adjustment if high - precision - sensitivity is required. G. Read the ovtical densitr of both the 0.04 o.u.m. standard and the simple a t 460 mp against thL6lank extract. If the optical density of 5 cm. of liquid is over 1.0, base comparisons on readings made using 1-cm. tubes. H. Compute the phenol content on a proportional basis, as the reaction is linear. I. If a t step D the sample is darker than the 0.20 standard, start comparisons immediately using the aqueous solutions. Read both the sample and the 1.0 p.p.m. standard against the aqueous blank a t 510 mp and calculate the phenol content of the sample on a proportional basis. SUMMARY
Investigation of the reaction between 4-aminoantipyrine and phenols for analytical purpows indicates the following factors to be significarrt: The reaction products may be roncentrated by extraction with chloroform in the case of all phenols investigated. The red aqueous dyes are extracted with chloroform to yield orange or yellow solutions. Serial extractions may be so arranged that the extraction is substantially quantitative and a large concentration factor is obtained. The aqueous reaction mixture is unstable. J'hen allowed to stand, the color produced by the reaction of phenol and 4-amino-
antipyrine fades. Concurrently, the color due to the reagents increases. The p H is an important factor in the control of the reaction. The maximum stability of color produced appears to be in the range 9.4 to 10.2. In order to minimize possible interferences, a range of 9.8 to 10.2 is recommended for the reaction mixture. Temperature is an important factor when small amounts of phenols are sought. Although the reaction appears to be affected only slightly by ordinary temperature variations, such variations affect the blank color significantly. With the chloroform-extraction procedure, the amount of 4aminoantipyrine used is largely responsible for determining the color of the blank. The reaction was linear over wide ranges of concentrations for a number of the simpler phenols. %%en aqueous solutions are compared to phenol standards a t 510 mp or chloroform extracts compared to phenol standards a t 460 mp, the results of examination of mixed phenols indicate the minimum amount of phenolic material which may be present. The procedure recommended for the examination of surface waters is sensitive to about 2 parts per billion of phenol when a single determination is made. The use of replicate or modified procedures can extend the reliable sensitivity to 1 part per billion. The background data presented should allow the devising of procedures especially adapted to other uses. LITER'ITURE CITED
(1) Emerson, Edgar, J . Org. C h e m . . 8, 417 (1943). (2) Emerson, Edgar, and Beegle, L. C.. Ibid., 8, 433 (1943). (3) Emerson, Edgar, and Kelley, Kenneth, Ibid.. 13, 532-4 (1948). (4) Ettinger, M . B., and Kroner, R. C . , Proc. 5th Industrial Waste
Conference, Purdue University, 1949. (5) Gottlieb, S., and Marsh, P. B., IND.ENG.CHEM.,ANAL.ED.,18, 16 (1946). (6) Martin, R. W., ASAL.CHEM.,21, 1419 (1949). (7) Stenger, V. A., and Greene, D. IT., private communication. RECEIVED January 2, 1951. Presented before the Division of Water, Seuage, and sanitation Chemistry a t the 118th Meeting of the AMERICAK CHEMICAL SOCIETY, Chicago, Ill.
Determination of Phenols in Aqueous Wastes from Coke Plants JOSEPH A. SHAW, Mellon Institute, Pittsburgh, Pa. It has become increasingly necessary in the coking industry to determine smaller concentrations than formerly of phenols in aqueous wastes from coke plants. Former methods, convenient for such analyses, frequently show insufficient delicacy. In an effort to remedy this situation the following procedure was developed. The purification procedure used in the bromine turbidimetric method is still employed, but w-here concentrations of phenol are
T
HE older convenient methods for determination of phenols in by-product coke plant waste, such as those employing
bromine-iodine titration and turbidimetric bromination, are frequently insufficiently delicate for present purposes. Available methods are much too time-consuming for practical use. The method here described is a combination of the bromine turbidimetric method described by Shalv (57 6 ) and a Procedure using 4aminoantipyrine, which was originah' suggested and studied by Emerson ( 2 , s )for the determination of phenol. APPARATUS
A steam cabinet is required, preferably a copper can 150 X 100 X 250 nun. deep with a flat lid with lugs on the underside to keep it from slipping. The can has slits 6 X 12 mm. deep in the upper edge, one a t one end and two a t the other end to accommo-
low a procedure is used in which a color is formed when a phenolic solution is treated with 4-aminoantipyrine and oxidized with potassium ferricyanide. This reaction must be brought about under rigidly controlled pH conditions. The delicacy of the method is about 20 parts per billion and a determination can be made in from 30 minutes to 2 hours, depending upon the amount of phenol in the sample and consequent concentration required. date the glass lead tubes and a direct steam tube for heating. In the bottom near one corner is a hole connecting with a 0.125-inch nipple to act as a drain. Two 200 X 25 mm. test tubes. One 200-mm. spiral condenser. One p H meter. SOLUTIONS AND CHEMICALS
Ethyl ether is purified by shaking with 10% sodium hydroxide, folloIved by a water wash and then a wash with faintly acid water containing methyl orange to remove causticity. Preparation of 4-aminoantipyrine, 0.5 gram in 25 ml. of water, about twice a week is suggested. Ammonium hydroxide, 2 ,V concentration. I t is usually satisfactory to dilute 15 ml. of 28% aqua ammonia with water to 100 ml. in a graduated cylinder. It should be prepared daily. Potassium ferricyanide solution, 2 grams dissolved in 100 ml. of water, is made fresh every 30 days.
1789
V O L U M E 2 3 , NO. 1 2 , D E C E M B E R 1 9 5 1 Standard stock solution of phenol, 1.000 gram per liter. Standards for bromine turbidity test are prepared by diluting 3.00 and 3.50 ml. of stock solution to 100-ml. volume with water to yield 30 and 35 p.p.m. solutions. Standards should be prepared daily. A working standard for the antipyrine procedure is made by diluting 2.5 ml. of the stock phenol solution to 1 liter. The stock solution can be kept for months. The 2.5 p.p.m. solution should be prepared daily. 1 ml. contains 0.0000025 gram of phenol. ~~
PROCEDURE
The procedure is described t o yield maximum delicacy. As such delicacy is only occasionslly required, much of the procedure can usually be eliminated. Concentration Step. Place a sample of waste in a separatory tunnel. The actual volume to be taken depends upon the concentration of phenols present; volumes greater than 500 ml. are lather awkward to handle. Add methyl orange and approximately 1 N sulfuric acid until the solution is just definitely acid. Add 3 or 4 drops of 10% cadmium chloride solution and render alkaline with 0.5 N sodium bicarbonate solution, adding 3 or 4 drops in excess. Shake the solution ivith three increments of the net ether. The volume of the first increment should be a t least 25% of the volume of the sample, and subsequent volumes 1570. Separate and place the ether layers in another separatory funnel. Discard the aqueous portion. Shake the ether with three 10-ml. increments of 10% sodium hydroxide solution. Collect the aqueous alkaline wash in a 50-ml. beaker. Discard the ether layer. Heat gently on an electric hot plate to remove ether, but do not boil vigorously or for a prolonged time. Make the aqueous alkaline solution to 50-ml. volume in a 50-ml. volumetric flask n ith distilled water. This solution is now ready for the distillation step. SOTE. Ether concentration as above described is usually necessary only where phenol concentration is extremely low, as in samples from a main plant sewer. For analyzing most plant samples, the ether step can be omitted and a 10-ml. sample of v aste acidified and steam-distilled directly. Ether washing also vonstitutes a purification of the sample, especially with respect to the salts, but these impurities can usually be sufficiently removed by the distillation procedure described. Purification Step (5). Prepare a gas scrubbing train of two 200 X 25 mm. test tubes with glass tubing and rubber stopper connections, Add distilled water to the first tube until it is a little more than half full. Place 10 ml. of sample (or of the aqueous alkaline solution if the ether extraction step has been used) in the second tube, add methyl orange, and just acidify n ith 1 to 1 sulfuric acid added dropmise. Adjust the stopper in the tubes and place tubes in the steam cabinet. Connect the inlet of the train to a source of compressed air or nitrogen and the outlet to the 8-inch spiral condenser. Turn steam into the cabinet and start air or nitrogen through the train a t the rate of 1 to 2 cubic feet per hour. This should-deliver about 1 to 2 drops of condensate per second. A flowmeter in the air line is desirable. Collect 25 nil. of distillate in a 25-ml. graduated cylinder, remove, and shake to mix. This distillate is now ready for phenol measurement. Determination Step. iit this point two methods are available to the analyst: (A) the turbidimetric bromine method and (B) the 4-aminoantipyrine method, The one actually used will depend upon the concentration of phenol in the distillate. Method A requires less time and is less subject to interfering conditions than Method B. In a 100 X 12 mm. serological tube place enough distillate to yield about 1.5 inches (3.75 cm.) of solution (about 4 ml.), and add a slight excess of nearly saturated bromine water as shown by a permanent light yellow color in the solution (usually 3 to 4 drops are required). Shake two or three times to mix. Look down through the tube against a neutral background in a visually suitable, somewhat subdued, light. If a turbidity is noticeable, the phenol concentration of the distillate is above 30 p.p.m. and Method A may be used. If no turbidity is noticeable, Method B must be used. METHOD A ( 5 ) . Prepare the two standard solutions of 30 and 35 p.p.m. Select three 100 X 12 mm. test tubes of equal volume from a stock determined by filling one with water and pouring i t into another. This will ensure tubes of similar cross section. The so-called serological tubes are preferred for this work. Dilute small portions of the distillate by trial and error until the solution xi11 yield a turbidity with bromine equivalent to 30 to 35 p.p.m.
of phenol. A 30 p.p.m. phenol solution will show only a faint turbidity upon bromination, while a 35 p.p.m. solution will yield a turbidity so dense that the bottom of the tube can be seen only with difficulty from above. Pour a portion of the 30 and 35 p.p.m. standards into two of the tubes and a portion of the suitably diluted distillate into the third tube. By flipping adjust the volumes of solutions to about 30 to 40 mm. in depth and an equal depth of solution in each tube. Shake the tubes in a beaker of water a t a temperature of 18" to 20" C. for about 1 minute to bring tubes to the same temperature. Add bromine water dropwise in excess to yield a yellow color of excess bromine, but avoid a large excess. About 3 drops are usually required in each tube. Grasp the three tubes across the top and give them two or three sharp shakes to mis. With the unknown tube between the two standard tubes, estimate by interpolation the concentration of standard matched, by looking downward through the tubes (not through the sides of the tubes) against a neutral background in a rather subdued light. Read the turbidity, not the color. The turbidity should be read after 30 seconds' delay and before 2 minutes' delay. Cresols are slightly slower than phenol in forming turbidity. Much longer delay than 2 minutes is apt to result in crystallization of the bromophenols and loss of turbidity. CALCULATIOK.
25 - = P.P.m. 10 of phenols in sample distilled (in terms of pure phenol) XETHOD B, for use where sample contains less than 100 p.p.m. phenols. Prepare a set of eight standard tubes in 50-ml. glassstoppered cylinders from the 2.5 p.p.m. standard phenol solution byplacing2.0, 2.5,3.0,3.5, 4.0,4.5,5.0,and 5.5ml. of thesolution in the cylinders and filling to the mark TTith water. Add exactly 1.00 ml. of the 2 N ammonium hydroxide solution to each tube, and invert several times to mix. Xext add exactly 0.5 ml. of the 4-aminoantipyrine solution to each tube and mix the samples. .4dd exactly 1.0 ml. of the ferricyanide solution to each tube. Mix the contents of the tube immediately after the addition of this last reagent. Set the cylinders in a dark closet for 20 minutes, after which time the solutions are ready to be used for comparison upon pouring into the Nessler tubes. The order of addition of the reagents and the mixing after each addition are important and must be adhered to. Exact amounts of the above reagents must be used; 1-ml. graduated capillary pipets are suggested for these measurements. All tubes must show a p H of 10.40 0.1 unit. Prepare the unknown samples in exactly the same manner as the standard, but use a suitable aliquot of the 25-ml. distillate in place of the 2.5 p.p.m. standard solution. I t is usually necessary to dilute the distillate before taking an aliquot. The comparisons can be made after 20 minutes' standing in a dark closet. Occasionally a slightly brown-pink tint will be seen in the unknowns. Apparently this is usually due to an excessive amount of thio salts and a low concentration of phenols. In such a case it is well to repeat the test using the ether step. As i t is not necessary to achieve concentration of phenols in this case, a smaller sample of waste and ether can be employed, n-ith consequent increase in facility of handling and decrease in fire hazard. I t is possible to interpolate roughly between the tubes of the above standard series. The average reading error under good test conditions should not be more than 0.0000006 gram of phenol, which, even a t the lowest part of the scale, would represent a t most less than 10% and a t the upper part less than 5y0 of error. P.p.m. of standard matched X dilution factor X
DISCUSSION OF METHOD
Blank determinations should be run for best results. I n this laboratory under the conditions of the test no positive color was obtained on blank determinations. The minimum color discernible would have calculated to a phenol concentration of 5 parts per billion. It was somewhat surprising that no color was obtained from the rubber stoppers of the Shaw still nor from the distilled water used, which had as its source the Allegheny River a t Pittsburgh, Pa. The city water during this period had no taste characteristic of chlorophenol. It does not follow, however, t h a t a zero blank would be obtained under all circumstances. Very little has been published about the amount of various phenolic homologs found in ammonia still waste produced by coke plants in the United States, There were available to the author analyses of recovered t a r acid from the ammonia liquor from four different coke plants, which were removing 95 t o 98% of the phenols in the waste. The synthetic solutions used in the following tests were based on the calculated averages of these
A N A L Y T I C A L CHEMISTRY
1790
Table I.
4Terage Anal3sis of Four Samples of Hecobered Tar Acids (70
Phenol o-Cresol m-Cresol p-Cresol 2,4-Diniethylphenol 3,4-Dimethyl phenol 2.5-Dimethylphenol 3.3-dimethyl phenol
68.2 3.9 13.4 7.3 1.8 1.8 1.8 1.8 __
100.0
Table 11. Tests on Solutions of Mixed Tar Acids (.\ITA solutions prepared from Ijure cheiiucals according to Table I) ilIihed T a r ~~~t kid, P.P.hI. yc No. Added Found Errol Remarks 2.34 6 . 4 - 10 days old 1 g./L stocka solution of .\ITA I 2.50 2.34 6.4Fresh 1 g./L stock solution of >ITA 2 2.50 2.44 2.4Solution contained 1000 p.p.m. each of 3 2.50 Na2Sz03 and KSCN, ether separation used 4 2 50 2.38 4.8Solution contained 1000 p.p.ni. each of Sa2SnOa and I.and a tentative conclusion reached that it \\-as prot)ahl>-of 90% or higher purity. It had a freezing point of 24.45" C. There u-:is no marked difference between this sample and the one of 21.1' c'. freezing point when treated with 4-aminoantipyrine reagpntd. This work \\-as carried no further, as 2,4-dimethj-lphenol comprises less than 2y0 of the phenolic bodies in still n-aste from coke plants.
Substances capable of,reducing potassium ferricyanide interfere with the 4-aniinoantipyrine test if present i n sufficient quantity (Table 11). I n coke plant liquors these are represented chiefly by hydrogen sulfide, thiosulfates, thiocyanates, cyanide, ferrocyanide, and organic reducing agents, AIost of the sulfur conipounds have a tendency t o produce brown colors instead of the characteristic pink colors. However, the described purification procedure is usually sufficient t o compensate for this difficulty. I n the fen instances where the brown color is obtained, the samples should be given the ether treatment even if concentration of phenols is not necessarj- (see Table 11). Ethyl alcohol, ethyl ether, or acetone added to the Sessler tubes t o the extent of 2y0 b>- volume had no noticeable effect upon color formation with phenol and 4aminoantipyrinr ; and 0.001 gram of 2,4-lutidine, placed in a Sessler tube with 0.00001 gram of phenol did not affect the color developed with the 4aminoant ipyrine reagent. Table 111. Fading of Color with Respect to Time Two series of tubes were prepared using 5.00 and 6.00 1111. of 2.5 g.p.111
phenol standard in each tube and treated as described. Pairs of tubes were prepared a t stated intervals and finally compared with a treshly prepared series of standards with the following results. The time of standing was recorded a4 starting immediately following the addition of the K3Fe(CS)a. Readings were taken after standards had stood 20 minutes. Time of Std. Std. 'b Expt, Standing, Alatched, Taken, IjH a t 26.3" C. I'ading Sos. Hours 111. MI. 1 2 3 4 5 6
7
8
j.25 3.25 3.25 3.25 1.50 1 .30 1.00 1.00
4.20 5.00 4.73 5.50 5.00 6.00 5.00 6.00
.i. 00 6 00 3.00 6.00 3.00 6.00 5.00 6.00
10.42 10.40 10.43 10.42 10.47 10.47 10.47 10.48
16 18 5 8 0 0
0 0
Hydrogen sulfide water %\-asadded to a series of standard tubes containing known amounts of phenol just after the ammonium hydroxide additions. In two tubes three times as much hydrogen sulfide was added as would be required theoretically t o reduce the ferricyanide. S o color was developed. Khen enough hydrogen sulfide was added to reduce 15% of the ferricyanide, the color n-as not affected, except perhaps t o slow don-n its forniation slightly.
V O L U M E 2 3 , NO. 12, D E C E M B E R 1 9 5 1 .\ sanipl(~of se\vagr t:ikrn f1,oiii a sewer in a rceideritial section of I'itts1)urgh \vas m d y z e d and showed 15 p.p.b. of phenols by this method. .$bout 2 or 3 hours later a portion of the same *ample was trcated with rnough phenol t o raise the initial concentration to 35 p.p.b. Analysis showed 30 p.p.b. I n the interim a little of the original phenol may have been destroyed by bactcarial action. For vtxry lo\\ concrmtrations of phenol it is dwirable t o use thc entirt, :ilkdine solution obtained in the ether concentration d t ('I,.
In such an instance 5 nil. of about 3yo sodium hydroxide solution are used for each treatment of the ether and shaken thoroughly each time. The alkaline solution is collec*ted directly in the distillation tube and, after the ether is driven off, it is i'aintljacidified with acid and the distillation is continued. Because of the relatively high concentration of sodium sulfate, the solution may tend to foam during distillation. This may be compensated for by placing on the inner xall of the tube a trace of Don- Antifoam B and cut'ting down on the rate of flow of air or nitrogen passed through the distillation system. llechanical carry-over n.ill be indicated by a red methyl orange color in the distillate.
&inattempt was made t o det,errnine the phenols in the Shaw distillate spectrophotometrically. The results below 2 or 3 p.p.m. phenol concentration were not satisfactory because of the presence of impurities of unknown nature. .\s it was desired t o stick to this pui,ification procedure because of its simplicity, further work with the ~pectrophotometerin this connection ir-as abandoned.
Table 11
.
Effect of p€I of Solution upon Color Formation
A set of standards was prepared with p H varying between 10.40 and 10.45, A series oi similar tubes \vas prepared containing varying amounts of SHdOH. Some contained no phenol and the others contained 3 ml. each o i standard phenol solution. Below a p H oi about 8.8 the reagents of them-
selves develop a color similar t o phenol. At just above this point maximum color is developed with phenol, diminishing as p H is increased. However this is too critical a point for convenient use, as the amount of alkali required is highly critical with respect to p H and the color varies greatly a t this point with respect t o pH. A pH of zt10.4 was considered optimum, as relatively large amounts of ammonium hydroxide can be added x i t h little effect on the p H of the solution. NHaOH .4dded,
1\11, of 2 5 S o h . 0.00 0.02 0.04 0.06 0.25 0.50 0.7i 1.00 1.25 1 . do
Phenol Added, A l l . Std.
0.00 0.00 0.00 0.00 3.00 3 00 3.00 3.00 3.00 3.00
Std. Tube Matched , .
.. ..
4:i5 4.00 3.25
3.00 3.00 2.80
pH 5.0 6.8 8.0 8.8 9.82 10.12 10.28 10.39 10.47 10.53
1791
\vith respwt t o t tic, pht,n~)l present. Tests were made, hoivever, t o deterinine thr. effwt, if any$ of varying the amount or proportiow of the rvitgrnt? added. Same interesting ohservatioris ivere niaiie. 4-.\niinoantip>-rine or potassium ferric~wiidr alone (in t hr. specifid concrntrations) placed in water niadt. t o pII 10.40 \r-ith ammoni:i haslittlr, ifany, effect upon t h e p H ofthesolution, but Imth takwi in admixture depress the figure l)y iici~t.I>.o w pH unit. I t is apparent from Table \- that an c~scwsof fcrric*yanidr tttiids t o give brown instead of pink tints. This e s c ~ wis not a direct function of the amount of ferric).aiiidr added, l)ut Icprrserits thc amount of unreduced ferricyanide left aftrr oxidation of the 4-aminoant ipyrine and other reducing agents preaent as a result of imperfect purification of the samplr. Iltduced ferricyanide conaidrmble ~'xcessof has relatively little tinctorial poir-er. ferricyanide will ruin the sample for visual comparison and nil1 introduce a large blank in a spwtrometric c'xuniination of ;in aqueous solution. It is evident that the reagrrit additions must be made with considerable care; otliertvise errdtic results \vi11 almost certainly he obtained. In Tal)le V, esperiments 3, 5 ) ant1 6, changes of from 1 t o 3 drops of reagent noticenlily changed the color in the test and in experiment 5 the color was completely unreadable. One- and 5-ml. graduated pipcat s were found coilvenient for addition of these reagents. For concentrations below 10 p.p.m.or where a tvaste has a11 unusually high concentration of thiosulfate, the ether separation should be used, as the sulfur dioxide produced in the hot acid solution may sufficiently contaminate the distillate t o destroy iiii important amount of the ferricyanide gent. The sulfur dioxide becomes relatively important in t e where :I large fractioii of the distillate must be used. Fundamental precision and delicncy of the nietliod are s h o ~ ~ n by the data for pure phenol in water in Table \.I and win" coiiiparative data on induPtrial wastes appear in Table VII. If the validit>-of a given data point is brought into question it should be checked, using the ether conr.eritr:itioii step : i d thc latter figurr accepted, as the ether Ir-ash removes many impurities that \vi11 interfere i f present in unudual twicentration. Thfl
Keiiiarks Deep red color Deep red color Red color Red color free Pink Pink Pink Pink Pink Pink
Table
Results of Varying Amounts of Lltiiinoantipyrine and Potassium Ferricvanide
(5.00 nil. of 2.5 p.p.m. standard phenol solution a n d 1.00 nil. of 2 .Y XHaO€i used in each test) -~ Reagent Used,
Exgt. So. 1 2 3
.f I t is important that thr, 4-aminoantipyrine color be developed a t a n accurately controlled pH, as can be seen in Table IV. The point of greatest stability with respect t o pH falls around 10.40. A 10.40 p H was accepted as optimum because i t can be duplicated within f 0 . 1 p H with reasonable certainty and very little color intensity is sacrificed Iiy this decision. The 1.00 ml. of 2 S ammonium hydroxide suggested by Martin (4)!vas adopted as a convenient and satisfactory alkaline agent. With this procedure the, p H falls consistently between 10.40 and 10.50 (see Table 111). Working in this range it is usually possible for plant control work largely t o dispense with the determination of pH on each individual tube. K i t h an unfamiliar sample or where critical results are required, the pH should be determined electrometrically. This can ordinarily be done after the color comparisons are made, as v-it,h the technique described, the pH test is largely confirmatory. I n an unumal case, where the p H falls outside the range of 10.30 t o 10.50, the tube should be disvarded and a new one prepared t o fall within that range. The amount of 4-aminoantipyrine and ferric>-anide reagent
\-.
6 b 0 10 '1
1\11,
I-.Iminoantipyrine
Potassium ferricyanide
0.60"
0.50 0.90 1.10 2.00
0.50" 0.50a 0.50n 0.25 0.45 0.55 1.00 0,25 1 .@0
4.30
5,OO
1,OO" 1 00" 1 00u 1 . 00u
0.50 2 00
Phenol l'ound, 111. Std. .i, 50 S o t readable
S o t readahle 6.00 ..i 00 4.00 5.23 S o t readable
pH a t 26.5' C'.
C'olot
Good
10 >Y 10 48 10 42 10 31 10.50 10 48 10.45 10.44 10 60 10.33
Fair t o good Fair to nood Brown Brorvn Fair to good Fair to good Poor, b r o n n Good Brown
.\mounts customarily used in method routine,
Table \ I . Plienol Added. P P 11 2.30 2 50 2 30 2.50 2 . .50 2.30
Tests on Solutions of Pure Phenol Phenol 1 ound, P P \I
.I\,. 2 . 52 P.P.B. 200 200 "5 25
P.P.B. 208 205 26.6 26.5
/ 1
c
Crroi 2,4+ 4.82.44 83.63 20 7-
4 0'
1
6.06 0-
ANALYTICAL CHEMISTRY
1792 Table VII. Saii:L4c 1
Sample 2 Jainlde 1
Sample Analyses of Certain Treated Ammonia Still Wastes Vntreated Lntreated L'ntreatcd Tre2ted with
500 p.p.rn. phenol-+amino antipyrine teat 509 p.p.m. phenol-bromine t.ut.i2i:netric rest 1100 p.p.rn. phenol-hron.ine t,irbi iirnetric tcit increasing ai?ioii1its oi a n o x i c l i z i i i ~agent
Phenol Found, P.P.31.
Units of Oxidizing Agents Used
48 3.4 2.5
2.5 5 0 8.4
10.0 Treated with active charcoal
1.3 Sample 2
9.4
author's experience indicates, however, that this will seldom be necessary. The time required for determining phenols by the described procedure varies from about 20 minutes for the bromine turbidimetric test t o about 2 hours for determining a 25 p.p.b. concentration by the 4-aminoantipyrine procedure. COiYCLUSION
h procedure has been developed for determination of any concentration of phenols likely to be met in aqueous wastes of I)y-product coke plants.
I t seems highly probable that the
method can be adapted for wide use. The adaptation must take into consideration both the type of phenolic bodies to be determined and the impurities to be removed. As might reasonably be expected, the results on the mixed tar acid solutions (Table 11)are noticeably lower than those on pure phenol (Table VI). This is presumably due in part to the p-cresol which, in isolated condition, a t least, gives no color with the 4-aminoantipyrine reagent, and to the difference in molecular weight of the alkylated phenols. The results given in Table VI1 on sample I, untreated, show the turbidimetric bromine test and the antipyrine test to be in good agreement, though the turbidimetric test is much quicker. The remainder of the figures illustrate the manner in which the effects of a progressive purification treatment of waste can be followed by meany of the proposed analytical method. LITER4TURE CITED
Baylis, J . Am. Wuter W o r k s Assoc., 19, 597-604 (1928). Emerson, J . O r g . Chem., 8, 417-19 (1943). Emerson and Kelly, Ibid., 13, 532-4 (1948). (4) Martin, ANAL.CHEM.,21, 1419 (1949). (5) Shaw, ISD. ENG.CHEM.,ASAL. ED.,1, 118 (1929). (6)Ibid., 3, 273 (1931). (7) Stevens, I n d . Eng. Chem.. 35, 655 (1943).
RECEIVED October 4, 1950. Contribution of the Fellowship o n Gas Purification sustained a t Mellon Institute by Koppers Co.. Inc.
Determination of Sodium Carboxymethylcellulose in Detergent Mixtures By the Anthrone Method HENRY C. BLACK, JR. Burnside Laboratory, E . I . du Pont de Nemours & Co., Inc., Penns Grove, N. J . A method was needed for determination of sodium carboxymethylcellulose in household detergents. The green color formed by reaction of anthrone with carbohydrate materials in sulfuric acid solution provided the basis for the present method. Color intensity is measured with a spectraphotometer. Controlled heating is necessary for reproducible results. Color intensity varies inversely with degree of substitution of the carboxymethylcellulose. The
I
S 1946, Dreywood ( 3 ) described a qualitative method for the
detection of carbohydrates by the use of anthrone (9,lOdihydro-9-ketoanthracene) in concentrated sulfuric acid. The formation of a green-colored complex indicated a positive test. Other investigators (6, 9) attempted to adapt the method to the quantitative estimation of carbohydrates. Viles and Silverman (9) described a procedure for the determination of cellulose in the dust of air samples collected in a textile mill. In this procedure, the dust was dissolved in 60% (by volume) sulfuric acid and a O.lyosolution of anthrone in 9570 sulfuric acid was added. The heat evolved on mixing developed the color. The solution was cooled after formation of the green color, and its transmittance at 625 mp was measured with a photometric instrument. The cellulose concentration was calculated from a calibration curve prepared in the same manner using known quantities of cellulose. Dreywood (3) demonstrated that positive results were obtained not only with carbohydrates but with certain carbohydrate
accuracy is 2% relative, provided the degree of substitution is known. Other carbohydrates, carbohydrate derivatives, furfural, 5-hydroxymethylfurfural, and certain polyoxyethylene derivatives of fatty acids and phenols are the only known interfering substances. The method should be useful for determination of carboxymethylcellulose in other mixtures and, with appropriate modification, of other carbohydrates and carbohydrate derivatives. derivatives as well. Samsel and DeLap ( 7 ) applied the anthrone reaction to the determination of methylcellulose. Initial attempts to apply the procedure developed by Viles and Silverman to the determination of sodium carboxymethylcellulose (NaCMC) in detergent mixtures were unsuccessful. Reproducible results were very difficult to obtain, primarily because of the lack of control of the heat evolved on mixing the sample and the anthrone reagent. In order to improve the reproducibility, it was necessary to eliminate the heat evolved on mixing and then develop the color by heating under controlled conditions. APPARATUS AND MATERIALS
All transmittance measurements were made with a Beckman Model D U spectrophotometer with 1.00-cm. Corex cells. Samples of sodium carboxymethylcellulose of low (0.1 t o 0.8) degree of substitution, manufactured as technical grade by
