(mon'' oh thye'' oh glis' er ol).
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C3H8O2S 108.16

1,2-Propanediol, 3-mercapto-.
3-Mercapto-1,2-propanediol [96-27-5].
» Monothioglycerol contains not less than 97.0 percent and not more than 101.0 percent of C3H8O2S, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight containers.
Specific gravity 841: between 1.241 and 1.250.
Refractive index 831: between 1.521 and 1.526.
pH 791: between 3.5 and 7.0, in a solution (1 in 10).
Water, Method II 921: not more than 5.0%.
Residue on ignition 281: not more than 0.1%.
Selenium 291: 0.003%, a 200-µL test specimen being used.
Assay— Dissolve about 400 mg of Monothioglycerol, accurately weighed, in 50 mL of water, and titrate with 0.1 N iodine VS, adding 3 mL of starch TS as the endpoint is approached. Each mL of 0.1 N iodine is equivalent to 10.82 mg of C3H8O2S.
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Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
USP35–NF30 Page 1872