Limit of 1,2,3-trimercaptopropane and related impurities—
Adsorbent, Standard buffer solution, Acid-washed solvent hexane, Diisopropyl ether, Solvent hexane-diisopropyl ether mixture, Chromatographic tube, and Chromatographic column—
Prepare as directed in the test for
Limit of 1,2,3-trimercaptopropane and related impurities under
Dimercaprol.
Procedure—
Place about 1 g of Injection, accurately weighed and demonstrated to be free from hydrogen sulfide as directed in the
Assay under
Dimercaprol, in a 5-mL beaker, add 2 mL of
Solvent hexane-diisopropyl ether mixture, and mix. Transfer the resulting solution to the prepared
Chromatographic column. When the liquid has passed into the column, wash the beaker with two 2-mL portions of
Solvent hexane-diisopropyl ether mixture, and allow the washings to fall to the level of the
Adsorbent. Proceed as directed for
Procedure in the test for
Limit of 1,2,3-trimercaptopropane and related impurities under
Dimercaprol. The limit of 1,2,3-trimercaptopropane (C
3H
8S
3) is not more than 4.5%, by weight, of the content of dimercaprol.
Other requirements—
It meets the requirements under
Injections 
1
, except that at times it may be turbid or contain small amounts of flocculent material.
Assay—
Transfer about 2 mL of Injection to a tared conical flask, and weigh accurately. Add 100 mL of a mixture of 1 volume of chloroform and 3 volumes of methanol, agitate to dissolve the Injection, and titrate with 0.1 N iodine VS to the production of a permanent yellow color. Perform a blank determination, and make any necessary correction. Calculate the percentage of dimercaprol (C
3H
8OS
2) in the portion of Injection taken by the formula:
0.6211(
V/
W 
v /
w),
in which
V is the volume, in mL, of 0.1 N iodine used;
W is the weight, in g, of Injection taken; and
v and
w are the volume, in mL, of 0.1 N iodine and the weight, in g, of Injection, respectively, used in the test for
Limit of 1,2,3-trimercaptopropane and related impurities.
