Analysis of Barbiturate Salts in Various Dosage Forms by an Ion Exchange and Nonaqueous Titration Procedure**School of Pharmacy, North Dakota Agricultural College, Fargo
✍ Scribed by Vincent, Muriel C. ;Blake, Martin I.
- Publisher
- Elsevier
- Year
- 1959
- Weight
- 199 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0095-9553
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✦ Synopsis
Barbiturate salts in various dosage forms are determined by liberating the barbituric acid from the salt by passage through a cation exchange resin. Dimethylformamide is used as the solvent. The barbituric acid is titrated visually with 0.1 N sodium methoxide in benzene-methanol. The method is rapid and avoids the tedious extraction procedure.
UCCESSFUL TITRATION of barbiturates in non-s aqueous solvents has been reported by numerous workers. Vespe and Fritz (1) determined barbiturates, pure and in dosage forms, by visual titration in dimethylformamide using sodium methoxide in benzene-methanol. It was noted that for tablets, the barbiturate may either be extracted prior to titration, or the powdered tablets may be titrated directly.
Pifer, Wollish, and Schmall (2) describe a procedure for the nonaqueous titration of barbiturates. Sodium salts of the barbiturates are determined by liberating the barbituric acid with sulfuric acid, followed by extraction with an organic solvent. Dimethylformamide is added and the solution is titrated with sodium methoxide.
Swartz and Foss (3) titrated barbiturates, as free acids, in a polyethylene glycol 400 and chloroform mixture. Titration was effected potentiometrically with sodium methoxide. Salts were extracted with chloroform, after acidification, using a Schmall extractor. The extracted barbituric acid was titrated by the proposed method.
Ryan, Yanowski, and Pifer (4) used lithium methoxide in benzene-methanol as titrant for barbituric acids and their salts. Salts, capsules, and tablets were extracted, after acidification, in a Schmall extractor or Squibb separator. The extracted barbiturates were titrated with lithium methoxide.
Chatten (5) titrated barbituric acids visually with potassium hydroxide in methanol, using chloroform as the solvent. It is indicated that barbiturate salts may be analyzed by liberation and extraction of the barbituric acid.
Ion exchange resins have been applied to the analysis of barbituric acids (6, 7), but not to the salts.