426
INDUSTRIAL AND ENGINEERING CHEMISTRY
were corrected for the small original active oxygen content of the rubber as determined in a separate analysis. Since many synthetic rubbers contain stabilizers (antioxidants) of some kind, attempts were made to learn whether such compounds have any effect on the determination. Phenyl-p-naphthylamine and Agerite White equivalent to 0.05 and 0.20 weiKht yo,respectively, based on the polymer solution were added to Butyl and t o Bum-S dissolved in benzene. Peroxide determinations resulted as follows:
Polymer Butyl Buna S
It can be analysis.
Active Oxygen Found, Inhibitor Absent P.B.N. A.W. P.p.m. P.p.m. 142 25 45 15
Active Oxygen Found in Presence of Inhibitor P.B.N. A.W. P.p.m. P.p.m 138 24 47 15
that these inhibitors do not affect the
Vol. 17, No. 7
ACKNOWLEDGMENTS
The authors thank those among their colleagues who aided with the work and the manuscript, particularly John Rehner for helpful consultation, and the Standard Oil Development Co. for permission to publish this work. LITERATURE CITED
(1) Bolland, J. L., Sundralingam, A , , Sutton, D. A,, and Tristram, G . R.,Trans. Inst. Rubber Ind., 17, 29-32 (1941). (2) Farmer, E. H., and Sutton, D. A , , J. Chem. SOC.,1942, 139-48. (3) Naylor, R. F., Trans. Inst. Rubber Id.,20, 45-53 (1944). (4) Robey, R. F., W'iese, H. K., and Morrell, C. E., IND.ENG. CHEM.,36, 3-7 (1944). (6) Willard, H. H., and Ayres, G. H., IND. EKG.CHEM.,ANAL.ED., 12, 287-91 (1940). (6) Young, C. A., Vogt, R. R., and Nieuwland, J. 1., Ibid., 8, 198-9 (1936). (7) Yule, J. A. C., and Wilson, C. P., IND.ENG.C H E M .23, , 1254-7 (1931).
Determination of Nitrate in Boiler W a t e r by Brucine Reagent C H A R L E S A. NOLL W. H. & L. D. Betz, Philadelphia, Pa.
B
KCAUSE of the widespread use of >odium nitrate and the maintenance of sodium nitrate-sodium hydroxide ratios in boiler water for controlling tendencies toward intercrystalline cracking, it has become imperati\ v that anefficient, accurate, and easily manipulated method for the determination of nitrate be provided, particularly for routine plant control. The nitrate method used by some chemists consists of the reduction of nitrate ion to ammonia which is then distilled over into standard acid and back-titrated (2). Another procedure involves distillation of the ammonia which is caught in distilled water and then directly Sesslerized ( 1 ) . The e methods are obviously rather tedious even for a well-equippeci laboratory and have not been widely adopted for plant control. The phenoldisulfonic method (I) for nitrate is also rather cumbersome and not well adapted to plant control. While this nitrate study was in progre.>s, a paper reported using brucine reapcmt for the determination of nitrate in soil and plant extracts (4). The range of nitratt. concentration investigated was considerably below the boiler water range and the brucine reagent used was in acid solution, requiring preparation just prior to using. A new method for the determination of nitrate in boiler water is herein described. The use of brucine reagent was suggested by Snell (S),who employed it for the deterniination of nitrate in meat. The procedure described adapts this method with some changes for the determination of nitrate in boiler water, employing a Klrtt-Summerson photoelectric photometer.
PROCEDURE AND STANDARDIZATION
Pipet two 5.0-ml. samples of the water to be analyzed into 50-ml. beakers; t o one beaker first add 0.2 ml. of brucine reagent and then to both beakers add 10 ml. of sulfuric acid. Add the acid to avoid s attering and mix thoroughly. (Clean dry glassw r e is preferagle in this test, although the addition of as much a s 0.5 ml. of water will not affect the result.) To the sample untreated with brucine add 10 ml. of distilled water, swirl to mix, cool, transfer a portion of the sample t o the 10-ml. test tube, and set the photometer to the zero reference point using the 470-mp filter. When the brucine-treated sample has stood a minimum of 3 minutes (not over 10 minutes), add 10 ml. of distilled water, mix, cool, transfer t o the photometer as above, and determine the dial reading. Read the nitrate equivalent to the dial reading
Table I. Time Effect after Sulfuric Acid Addition Time ,Win. 3 5 7 10 20 30
Nitrate as NO1
Found P.p.m. 25.0 25.0 25.0 25.5 33.0 37.2
Table II. Stability of Color Developed Time of Standing after Sample Preparation
.Win. 0 30 60
REAGENTS AND CONDITIONS
POTASSIGN KITRATE Reaient grade potassium nitrate is dried in an oven at 105" * 1' C. for 24 hours and 1.631 grams are accurately weighed, dissolved in approximately 20 ml. of distilled water, and made up to 1 liter with distilled water. The solution strength is then 1 ml. = 1 mg. as NO?. BRUCINEALKALOID. Five grams of pure brucine alkaloid crystals are dissolved in approximately 20 ml. of chloroform and made up to 100 ml. with chloroform (reagent grade). (Brucine is a very poisonous alkaloid and care should be taken in handling it.) SKLFURIC ACID. Sulfuric acid, reagent grade, specific gravity 1.84 and possessiiig 95 to 96% assay. ~ L E T T - S U M h l E R S O N PHOTOJIETER. .A 10-ml. test tube, 13 mm. wide, 470-mp color filter.
Present P.p.m. 25.0 25.0 25.0 25.0 25.0 25.0
90
120
Table 111. A g e of Reagent
Days 0 1
7 14 30 40 60
Present P.p.m. 25.0 25.0 25.0 25.0 25.0
A g e of
Nitrate as N0a
Found P.p.m. 25.0 25.1
25.2 24.3 23.8
Brucine Reagent
Present P.p.m. 25.0 25.0 25.0 25.0 25.0 23.0 25 0
Nitrate as NO,
Found P.p.m. 25.0 25.0 25.0 25.0 25.2 24.8 25.1
ANALYTICAL EDITION
July, 1945
Figure 1 .
Sample Curve for Photometer Calibration
from a calibrated curve obtained using solutions of known nitrate values. A sample is shown in Figure l. Although the yellow color absorbs more illumination at 400 and 420 mp, the 470-mp filter was used in order to obtain a reasonably long range of concentration. However, the curve flattens out above 55 p.p.m. of nitrate and for concentrations in excess of this value dilution of the sample is required. The sensitivity of the method is about 0.3 p.p.m. and the accuracy of the test is ap'proximately 0.5 p.p.m. EFFECT OF IONS AND CONDITIONS
After preparation of the curve standard nitrate solutions were employed to determine whethei or not temperature of the solution being tested affected the results and it was found that
Table IV. Effect of Possible Interfering Ions Ion Nitrate aa NOI Nitrate a8 NO: Present Found Present Found Present
Ion Present
P.p.m.
P.p.m.
10.0 2.0 2.0 10.0 10.0
Pam.
Sodium Nitrite 0.0 10.0 40.0 10.0 40.0
0.0 10.0 40.0 10.4 39.8
Chloride 100 200 200 500 500 1000 1000
25.0 25.0 5.0 5.0 25.0 5.0 25.0
Quebracho Tannin P.p.m.
50 50 50
100
100 160
150
P.p.m.
100 50 100 loo 200 200
P.p.m.
P.p.m.
Orthophoaphate 0.0 10.0 40.0 10.0 40.0 10.0 40.0
50 25 25 50 50
A B C
D E
The procedure developed for the determination of the nitrate ion in boiler water is unaffected by the ions normally present in boiler water with the exception of high color concentrations. The effect of high color can be overcome by dilution. The met hod is rapid and well adapted to plant control. I n the range
0.0 10.1 40.3 10.1 40.2
0.0 10.0 40.0 10.0 40.0
Table V. Effect of Organic Matter Apparent Color Nitrate aa NO1 Found at pH 10.5 Present P.p.m. Unifa P.p.m. 0.0 0.0 400 400 5.0 4.3 400 40.0 40.3 800 5.0 6.0 800 40.0 40.1 900 5.0 4.0 900 40.0 30.0
Nitrate aa NO, Present
Total Nitrate a8 NO: after Adding 10 P.P.M. NO,
Nitrate aa NO1 Found
8.0 22.7 15.8 36.5 11.5
18.0 32.7 25.8 46.5 21.5
18.0 32.7 26.0 47.0 21.8
P.p.m.
P.p.m.
P.p.m.
VI.
Table
Present
A B C D
E
Nitrate
88
NOS
Found
P.p.m.
P.p.m.
10.0 15.0 20.0 35.0 36.5
10.4 15.1 19.4 35.1 37.0
Tests on Boiler Water
P.p.m.
P.p.m.
P.p.m.
0 66 0 24 0
220
492 420 584 328 364
84
VII. Variation between Operators
Operator
P M Hardness Alkalinity Alkabnity as CaCOa asCaC0, 88 CaCOi
208 0 204
from 20" to 80" C. no temperature interference was obtained. I n addition the period of timing necessary after the addition of sulfuric acid and the age of brucine indicator were investigated (Tables I, 11, and 111). The color developed was stable for a t least one hour. In the range of 0.1 to 0.4 ml. of brucine reagent no effect was noted on the nitrate determination. Concordant results were obtained with the brucine reagent obtained from two different manufacturers. The effect of possible interfering ions is shown by Tables IV and V. With the exception of the organic matter, no interference was caused by the ions investigated. Tannin and color concentrations as high as 100 p.p.m. and 800 units, respectively, are rarely encountered in boiler water under normal conditions. Unsuccessful attempts were made to oxidize this color by potrtssium permanganate and other oxidizing agents. Where such high color concentrations are encountered in a boiler water, it is necessary to dilute the sample prior to employing this method of nitrate determination. No interference or effect on the nitrate test was found on investigating ferrous and ferric ion concentrations as high as 20 p.p.m. as Fe, methyl orange alkalinity as high as 2000 p.p m. aa NaOH, ammonium ion as high as 50 p.p.m. as N, calcium and magnesium each as high as 250 p.p.m. as CaCOa, and sodium silicate as high as 200 p.p.m. aa SO2. I n order to show the effectiveness of the method an ~ t i i l t l boiler water, boiler water of known nitrate content was prepared from samples obtained in different sections of the country. In all cases, blanks were run to determine the original nitrate present, using the procedure described in this paper. I n each case, 10.0 p.p.m. of nitrate as NO8 were then added to the boiler water, and the samples were well mixed and permitted to stand overnight. The total nitrate was determined the following day. Table VI shows that the values obtained are within 1 0 . 5 p.p.m. of the known value. The concordancy of different operaton using the described method was studied by supplying standard solutions of known nitrate value to each operator &s samples, without the operator knowing the value of the sample. The results shown in Table VI1 indicate very little variation among different operators. CONCLUSIONS
Sodium Metaphosphate
24.8 24.9 4.9 5.0 25.1 5.1 25.2
Table
Plant
0.0 10.0 40.0 10.0 40.3 10.3 40.0
427
pH 11.1 10.3 10.3 7.7 10.5
Phosphate as Po4
p.p.m.
175 75 125 15 35
Chloride Sulfate 88 Cl a8 so4 P.p.m.
P.p.m.
116 172 72 292 300
544 496 320 512 608
Appar- Specific ent ConductColor ance Units
Micromhoa
325 250 500 25 80
2250 2000 1800 2250 2500
Silics a8 Si01 P.p.m.
90 90 125 90 70
428
INDUSTRIAL AND ENGINEERING ChEMISTRY
of nitrate concentrations from 0 to 50 p.p.m. as NOa,an accuracy of approximately 0.5 p.D.m. can be obtained. ACKNOWLEDGMENT
The author wishes to express appreciation to W. H. & L. D. Beta, in whose laboratories this investigation was conducted. The assistance of H. L. Kahler, E. C. Feddern, and J. J. Maguire is a130 gratefully acknowledged.
Vol. 17, No, 7
LITERATURE CITED
Jordan, H. E., ed., “Standard Methods of Water Analysis”, 8th ed., pp. 48-50, New York, American Public Health Association, 1936. (2) Schroeder, W. C., and Berk, A. A., U.S. Bur. Mines, Bull. 443, p. 83 (1941). (3) SnelL F. D., and Snell, C. T.,“Colorimetric Methods of Analysis”, 2nd ed., Vol. 1, p. 635, New York, D. Van Nostrand Co., 1936. (4) Wolf, B., IND. ENS.CHEM.,ANAL.ED.,16, 446 (1944). (1)
Determination of Active Hydrogen Using the Grignard Reagent in Pyridine ROBERT A. LEHMAN AND HELEN BASCH N e w York University Ccllege of Medicine, N e w York 16,
A method i s described for determining active hydrogen by means of the reaction of the unknown substance with a suspension in pyridine of the Grignard-pyridine complex. The apparatus and procedure are derived from those of Fuchs, Ishler, 4nd Sandhoff (2) with substantial modifications. The results are satisfactory and the use of pyridine makes the technique available for the analysis of an extensive series of organic compounds.
T
HE application of the Grignard reagent to the gasometric determination of active hydrogen p’as first described by Zerewitinoff (IO), who showed &s early as 1907, in connection with the necessary determination of the blank, that when carefully dried pyridine is used in the procedure, it forms a precipitate with methyl magnesium iodide in amyl ether. This precipitate has the probable formula (CsH6N)2.CH3MgI.’(C5H11)?0.A considerable quantity of gas is evolved a t the same time, and additional gas is liberated on standing or heating. By operating rapidly and a t room temperature Zerewitinoff was nevertheless able to report satisfactory results with this solvent. Odd0 (6) obtained similar data using ethyl magnesium iodide in pyridine. Tanberg (8), on the other hand, using various specimens of pyridine, concluded that, it was not a satisfactory solvent for this purpose. Flaschentrager ( 1 ) developed a micromethod using a mixture of amyl ether and pyridine. His results were reasonably accurate but the gas evolved from the blank in some cases amounted to 50% of that from the sample. Recently a convenient method and apparatus for the microdetermination of active hydrogen hm been described by Soltys (7). I n this procedure, however, as in that of Flaschentrager, the first rush of gas evolved when the Grignard resgent is mixed with pyridine is inherently included in the blank, thus making the blank high and not altogether reproducible. The method of Fuchs, Ishler, and Sandhoff (2) A for the determination of active hydrogen was tested and found to be simple and rapid but useful only for the limited group of organic compounds which are soluble in butyl ether. I n attempting to substitute pyridine as a solvent of wider range of applicability, the authors obtained low results which approached nearer and nearer to the theory as more samples were run in the same charge of reagent. This error appeared to be due to the solubility of methane in pyridine and was eliminated when purified methane was used as the inert atmosphere. The apparatus of Fuchs and co-workers ( 2 ) , which, for convenience, is shown in Figure 1, was modified in several respects. The gas buret and reaction chamber were waterjacketed. Pressure tubing connections were
N. Y
inserted a t B , D, and F , so that it was possible to shake the reaction chamber during the reaction and the equilibration of the gases. Since it was usually necessary to raise the temperature and this led to condensation of the solvent in the iron reagent cups, the cups were provided with loosely fitted brass caps about 4 mm. deep, which prevented the condensate from washing the sample into the chamber during determination of the blank. A small thermometer was hung on the gas inlet tube. At the end of the gasdrying train a reservoir for pyridine was added. This was filled with about 30 cc. of pyridine and connected to the gas inlet stopcock. Thus, the gas was saturated with pyridine vapor a t all times and liquid pyridine could be forced into the reaction chamber by tilting the reservoir. Diethylphthalate was found t o be a suitable manometer liquid. MATERIALS
Methane gas, 92% pure, was obtained from the Matheson Company, East Rutherford, N. J., and purified further by the washing train of Kohler, Stone, and Fuson ( 3 ) . Approximately 0.6 N methyl magnesium iodide solution was prepared as described by the same authors, using diethyl instead of diisoamyl ether. Reagent grade pyridine was refluxed several hours over potassium hydroxide pellets and redistilled. PROCEDURE
Samples were dried in the oven a t 110’ C. when possible, or otherwise in a desiccator over phosphorus pentoxide. Ten cubic centimeters of Grignard reagent were transferred to the reaction chamber with a pipet. The sample was then quickly weighed
D
n G
--J
7
Figure 1.
Diagram of Apparatus
