Preparation of Stable Sodium Thiosulfate Solutions
1
Preparation of Stable Sodium Thiosulfate Solutions JARIES L. KASSNER AND ESTHER E. K.ISSSER University of Alabama, University, Ma. GREAT many investigations (1-8, 10, 11) of the preser- A vation of sodium thiosulfate solutions have been made. Stable solutions of sodium thiosulfate are generally pre- pared (3) by dissolving sterile sodium thiosulfate crystals in freshly boiled and cooled distilled water. Many solutions prepared by this procedure maintain a constant titer over a long period of time, while other solutions prepared in exactly the same way decompose. Since sulfur-eating bacteria, Thioban’llus thioparus, are present in the air, the stopper may become contaminated before the bottle is closed or later when the bottle is opened. As a result, not all solutions prepared by using freshly boiled water are sterile. The present investigation was started in an effort to find a better method for preparing stable solutions of sodium thio- sulfate. It seemed logical to assume that some poison could be found that would prevent the growth of the sulfur-eating TABLE I. EFFECT OF CHLOROFORM ON NORNALITT CHClP Dec., 1936 hlay, 1937 luov , 1938 Nov., 1939 hlar., 1940 Ml./l. ,\T .v s .v s 0.07 0,1057 0,1056 0.1054 0.1055 0.1054 0.30 0.0963 0,0963 0.0963 0.0963 0.0963 0.15 0.0852 0.0852 0.0852 0.0852 0.0852 a No more chloroform was added after the first day. bacteria and would not interfere with t’he subsequent use of the solution. -4 preliminary investigation showed that chlo- roform offered the most promise of preventing the growth of these bacteria. It is a good germicide, practically insoluble in water, and soluble in rubber. Khen a few drops are added to a solution in a rubber-stoppered bottle, the chloroform dif- fuses up through the solution and dissolves in the stopper. It later diffuses out of the stopper into the air space above the solution, and keeps the solution sterile over a long period of time, even though the bottle is opened frequently. To see whether the addition of chloroform to a solution affected its titer, an approximately 0.05 N solution of sodium thiosulfate, containing 3 drops of chloroform per liter, was prepared and standardized. More chloroform was then added in 0.1-ml. por- tions and the solution was restandardized until 0.5 ml. of chloro- form had been added to 1 liter. The addition of 0.5 ml. of chloro- form to 1 liter (the total time that elapsed during this addition was 3 days) of sodium thiosulfate did not affect the fourth signifi- cant figure in the normality of the solution. In all this work the solutions were standardized with a solution of potassium iodate (9) of approximately the same normality as the thiosulfate solution. The first st’andardization was made each time within less than 2 hours after the solution was prepared. Bureau of Standards potassium iodate, calibrated weights, and calibrated volumetric apparatus were used throughout this in- vestigation. The solutions were prepared from ordinary distilled water and had a pH of 6.2 to 6.8. If the pH of the distilled water is un- known, it is advisable to add about 0.01 gram of sodium carbonate per liter. The pH of distilled water can be changed from 5.2 to 9.3 by adding 0.01 gram of sodium carbonate per liter. The sodium thiosulfate used in this work was not recrystallized or sterilized in any way before use. The solutions were stored in clear glass, rubber-stoppered bottles. The rubber stoppers were cleaned by boiling in dilute caustic solution. Further steriliza- tion is not necessary because the chloroform dissolves in the stoppers. The data for the more concentrated dutions are sum- marized in Table I. The solutions were not protected from the light but were not exposed to the direct rays of the sun. Unfortunately, the first dilute solutions (0.05 to 0.006 N) mere prepared and stored in clear glass, glass-stoppered bot- tles. These solutions maintained their titer to within less than 0.3 per cent from December, 1937, to May, 1938, but their normality had decreased so much by Sovember, 1938, that they were discarded and a new series was started. This time 3 liters of each solution were prepared and divided into three portions. Series A contained only water plus the sodium thiosulfate and was stored in ordinary glass, rubber-stoppered bottles. A white precipitate formed in each bottle within 6 months. Tests showed that the normality had decreased. To each portion of series B and C 0.4 ml. of chloroform per liter was added. Series B was stored in clear glass, rubber- stoppered bottles and series C was stored in dark brown (1,4) rubber-stoppered bottles. The data are summarized in Table 11. Chloroform has been used as a bactericide in the preserva- tion of sodium thiosulfate solutions in this laboratory for the past 5 years. TABLE 11. Series Nov., 1938 N B 0.05262 0,02646 0.01406 0.006778 C 0,05252 0.02646 0.01406 0.006778 (1 No more chloroform was first prepared. EFFECT OF CHLOROFORM^ May, 1939 Nov., 1939 Mar., 1940 N AV N 0.05252 0.05232 0.05207 0.02643 0.02875 0.02556 0.01405 0.01378 0.01364 0.006695 0.006663 0.006640 0.05251 0 .05250 0.05251 0.02647 0.02645 0.02646 0.01406 0.01404 0.01405 0.006776 0.006772 0.006774 i added in series B and C after the solutions were Summary Small amounts of chloroform prevent the decomposition Solutions of approximately 0.05 N or less should be stored Sterile sodium thiosulfate solutions that have a pH of 6.2 or of sodium thiosulfate stored in rubber-stoppered bottles. in brown glass, rubber-stoppered bottles. more maintain their titer over a long period of time. Literature Cited (1) Bellucci, Italo, and Damiani, I., Gaze. chim. ital., 64, 69 (1934). (2) Campbell, F. H., and Xatson, F. J., Chem. Eng. Mining Reu., (3) Xilpatrick, M., Jr., and Kilpatrick, >I. L., J. Am. Chem. Soc., 22, 340 (1930). 45. 2132 (1923). (4) Kolthoff, I: M.; Pharm. Teekblad, 56, 878 (1919); 2. anal. (5) La Mer, V. K., and Tomlinson, H. M., IND. ENO. CHEM., Anal. Chem., 60, 344 (1921). Ed., 9, 588 (1937). (6) Rice, F. A,, Kilpatrick, M., Jr., and Lemkin, Km., J. Am. Chem. Soc., 45, 1361 (1923). (7) Topf, G., 2. anal. Chem., 26, 137 (1887). (8) Katson, F. J., SOC. Chem. Ind. Vzctorza PIOC., 32, 679 (1932). (9) Willard and Furman, “Elementary Quantitative Analysis”, 3rd ed., p. 269, New York, D. Van Nostrand Co. (1940). (10) Winkler, L. W., Pharm. Zentralhalle, 69, 369 (192s). (11) Yoshida, I., J. Chem. SOC. Japan., 48, 26 (1927).
description
Preparation of Stable Sodium Thiosulfate Solutionsby JARIES L. KASSNER AND ESTHER E. K.ISSSERUniversity of Alabama, University, M a
Transcript of Preparation of Stable Sodium Thiosulfate Solutions
Preparation of Stable Sodium Thiosulfate Solutions JARIES L. KASSNER AND ESTHER E. K.ISSSER
University of Alabama, University, M a .
GREAT many investigations (1-8, 10, 11) of the preser- A vation of sodium thiosulfate solutions have been made. Stable solutions of sodium thiosulfate are generally pre-
pared (3) by dissolving sterile sodium thiosulfate crystals in freshly boiled and cooled distilled water. Many solutions prepared by this procedure maintain a constant titer over a long period of time, while other solutions prepared in exactly the same way decompose. Since sulfur-eating bacteria, Thioban’llus thioparus, are present in the air, the stopper may become contaminated before the bottle is closed or later when the bottle is opened. As a result, not all solutions prepared by using freshly boiled water are sterile.
The present investigation was started in a n effort to find a better method for preparing stable solutions of sodium thio- sulfate. It seemed logical to assume that some poison could be found tha t would prevent the growth of the sulfur-eating
TABLE I. EFFECT OF CHLOROFORM ON NORNALITT CHClP Dec., 1936 hlay, 1937 luov , 1938 Nov., 1939 hlar . , 1940 M l . / l . ,\T .v s .v s 0.07 0,1057 0,1056 0.1054 0.1055 0.1054 0.30 0.0963 0,0963 0.0963 0.0963 0.0963 0.15 0.0852 0.0852 0.0852 0.0852 0.0852
a N o more chloroform was added after t he first day.
bacteria and would not interfere with t’he subsequent use of the solution. -4 preliminary investigation showed that chlo- roform offered the most promise of preventing the growth of these bacteria. It is a good germicide, practically insoluble in water, and soluble in rubber. K h e n a few drops are added to a solution in a rubber-stoppered bottle, the chloroform dif- fuses up through the solution and dissolves in the stopper. It later diffuses out of the stopper into the air space above the solution, and keeps the solution sterile over a long period of time, even though the bottle is opened frequently.
To see whether the addition of chloroform to a solution affected its titer, an approximately 0.05 N solution of sodium thiosulfate, containing 3 drops of chloroform per liter, was prepared and standardized. More chloroform was then added in 0.1-ml. por- tions and the solution was restandardized until 0.5 ml. of chloro- form had been added to 1 liter. The addition of 0.5 ml. of chloro- form to 1 liter (the total time that elapsed during this addition was 3 days) of sodium thiosulfate did not affect the fourth signifi- cant figure in the normality of the solution.
In all this work the solutions were standardized with a solution of potassium iodate (9) of approximately the same normality as the thiosulfate solution. The first st’andardization was made each time within less than 2 hours after the solution was prepared. Bureau of Standards potassium iodate, calibrated weights, and calibrated volumetric apparatus were used throughout this in- vestigation.
The solutions were prepared from ordinary distilled water and had a pH of 6.2 to 6.8. If the pH of the distilled water is un- known, it is advisable to add about 0.01 gram of sodium carbonate per liter. The pH of distilled water can be changed from 5.2 to 9.3 by adding 0.01 gram of sodium carbonate per liter. The sodium thiosulfate used in this work was not recrystallized or sterilized in any way before use. The solutions were stored in clear glass, rubber-stoppered bottles. The rubber stoppers were cleaned by boiling in dilute caustic solution. Further steriliza- tion is not necessary because the chloroform dissolves in the stoppers.
The data for the more concentrated d u t i o n s are sum- marized in Table I.
The solutions were not protected from the light but were not exposed to the direct rays of the sun.
Unfortunately, the first dilute solutions (0.05 to 0.006 N) mere prepared and stored in clear glass, glass-stoppered bot- tles. These solutions maintained their titer to within less than 0.3 per cent from December, 1937, to May, 1938, but their normality had decreased so much by Sovember, 1938, that they were discarded and a new series was started. This time 3 liters of each solution were prepared and divided into three portions. Series A contained only water plus the sodium thiosulfate and was stored in ordinary glass, rubber-stoppered bottles. A white precipitate formed in each bottle within 6 months. Tests showed that the normality had decreased.
T o each portion of series B and C 0.4 ml. of chloroform per liter was added. Series B was stored in clear glass, rubber- stoppered bottles and series C was stored in dark brown (1,4) rubber-stoppered bottles. The data are summarized in Table 11.
Chloroform has been used as a bactericide in the preserva- tion of sodium thiosulfate solutions in this laboratory for the past 5 years.
TABLE 11. Series Nov., 1938
N B 0.05262
0,02646 0.01406 0.006778
C 0,05252 0.02646 0.01406 0.006778
(1 N o more chloroform was first prepared.
EFFECT OF CHLOROFORM^ May, 1939 Nov., 1939 Mar., 1940
N AV N 0.05252 0.05232 0.05207 0.02643 0.02875 0.02556 0.01405 0.01378 0.01364 0.006695 0.006663 0.006640 0.05251 0 .05250 0.05251 0.02647 0.02645 0.02646 0.01406 0.01404 0.01405 0.006776 0.006772 0.006774
i added in series B and C after the solutions were
Summary Small amounts of chloroform prevent the decomposition
Solutions of approximately 0.05 N or less should be stored
Sterile sodium thiosulfate solutions that have a p H of 6.2 or
of sodium thiosulfate stored in rubber-stoppered bottles.
in brown glass, rubber-stoppered bottles.
more maintain their titer over a long period of time.
Literature Cited (1) Bellucci, Italo, and Damiani, I., Gaze. chim. ital., 64, 69 (1934). (2) Campbell, F. H., and Xatson, F. J., Chem. Eng. Mining Reu.,
(3) Xilpatrick, M., Jr., and Kilpatrick, >I. L., J. Am. Chem. Soc., 22, 340 (1930).
45. 2132 (1923). (4) Kolthoff, I: M.; Pharm. Teekblad, 56, 878 (1919); 2. anal.
(5) La Mer, V. K., and Tomlinson, H. M., IND. ENO. CHEM., Anal. Chem., 60, 344 (1921).
Ed., 9, 588 (1937). (6) Rice, F. A,, Kilpatrick, M., Jr., and Lemkin, K m . , J . Am. Chem.
Soc., 45, 1361 (1923). (7) Topf, G., 2. anal. Chem., 26, 137 (1887). (8) Katson, F. J., SOC. Chem. Ind. Vzctorza PIOC. , 32, 679 (1932). (9) Willard and Furman, “Elementary Quantitative Analysis”,
3rd ed., p. 269, New York, D. Van Nostrand Co. (1940). (10) Winkler, L. W., Pharm. Zentralhalle, 69, 369 (192s). (11) Yoshida, I., J. Chem. SOC. Japan., 48, 26 (1927).
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