AOAC Official Method 931.11 Iodoform Drug Substance Gravimetric Method
First Action 1931
Final Action
A. Reagents
(a) Ammonium thiocyanate standard solution.—0.05M, 942.26 (see A.1.02). Standardize against 0.1M AgNO3, 941.18 (see A.1.11), using equal volume alcohol and 3 mL FeNH4(SO4)2 solution as indicator.
(b) Ferric ammonium sulfate indicator.—Dissolve 8 g FeNH4(SO4)2×12H2O in 100 mL H2O.
B. Determination
Accurately weigh ca 0.25 g CHI3 and transfer quantitatively to 200 mL Erlenmeyer. Add 40 mL alcohol, swirl gently until CHI3 dissolves, filter if necessary, and immediately add 40 mL 0.1M AgNO3 and 10 mL HNO3. Swirl gently ca 5 min, let stand at room temperature 2–3 h, and then swirl occasionally as aid in flocculating the AgI. Titrate excess AgNO3 with 0.05M NH4SCN, using 3 mL of the FeNH4(SO4)2 indicator. 1 mL 0.1M
AgNO3 = 0.01312 g CHI3. Or: Proceed as in 932.17 (see 18.3.04), last paragraph beginning “Collect AgI on weighed Gooch, . . .”.
Reference: JAOAC 14, 370(1931).
CAS-75-47-8 (iodoform)
