Liquid chromatographic assay of ascorbic acid, niacinamide, pyridoxine, thiamine, and riboflavin in multivitamin-mineral preparations.

A simple and rapid method is presented for the liquid chromatographic assay of ascorbic acid, niacinamide, pyridoxine, thiamine, and riboflavin from a single chromatogram. Ion-pair chromatography with a reverse phase C18 cartridge in a radial compression system is used. Quantitation is excellent with a total analysis time of less than 20 min. A mobile phase of methanol-water (15 + 85) (0.005M heptanesulfonic acid) with 0.5% triethylamine at pH 3.6 and a flow rate of 2.0 mL/min gives the most satisfactory separation of the 5 water-soluble vitamins. By using 2 detectors in series set at different wavelengths and sensitivities, all 5 vitamins, with peak heights on scale, can be measured from a single injection; peak elution order is ascorbic acid, niacinamide, pyridoxine, thiamine, and riboflavin. Ascorbic acid is measured at 254 nm and the other vitamins, at 280 nm. The amount of amine modifier in the mobile phase is critical to the separation of niacinamide and pyridoxine. Recoveries of 5 water-soluble vitamins from spiked placebos were in the range of 98.2-102.0%. Confidence limits, +/- 3 SD, were in the range of 1.0-5.4%. Overall, the results obtained using the liquid chromatographic method show excellent agreement with manual methods and automated analysis.

Ion-pair reversed-phase high-pressure liquid chromatography of cough-cold syrups I: pseudoephedrine hydrochloride, brompheniramine maleate, and dextromethorphan hydrobromide.

Pseudoephedrine hydrochloride (I), brompheniramine maleate (II), and dextromethorphan hydrobromide (III) in a cough-cold sytup were separated and determined by ion-pair reversed-phase high-pressure liquid chromatography. The separation was carried out using a muBondapak C18 column (30 cm x 3.9 mm i.d.) and a mobile phase of acetonitrile-water-acetic acid (40:60:1) with 0.01 N 1-octanesulfonic acid sodium salt and 0.05 N potassium nitrate. Detection was accomplished using a UV detector at 265 nm for I and II; III was monitored at 280 nm. Concentration versus peak height plots in the ranges of 0.37-1.9 mg/ml for I, 0.025-0.126 mg/ml for II, and 0.125-0.625 mg/ml for III were linear. Ten consecutive injections of a mixture gave a percent relative standard deviation of less than 1% for all three components. Average recoveries from laboratory-prepared samples were 100.5% for I, 100.9% for II, and 100.1% for III. No precolumn cleanup was necessary, and the chromatogram was complete in 16 min.

Chromatographic separation and assay of morphine in tablets.

A method specific for the determination of morphine sulfate in tablets was developed. Morphine is separated from the excipient and degradation products by a column chromatographic method. The eluate containing morphine is extracted into an acid solution and determined spectrophotometrically. Recovery from standard solutions is greater than 99%. This method is more specific for the separation and determination or morphine in tablets than is the USP XVIII procedure.

Reverse phase thin-layer chromatographic separation of bromodiphenhydramine and diphenhydramine.

A thin-layer chromatographic system is described for the separation of diphenhydramine and bromodiphenhydramine which is based on a reverse phase paper chromatographic system developed by J. Vecerková (2,3) in 1962. Chromatographic systems for this separation described in the literature and several systems attempted in this laboratory using normal chromatography have not proven successful. The method using reverse phase thin-layer chromatography involves a stationary phase of mineral oil on silica gel G and a mobile phase of ethanol:water:ammonium hydroxide, 28% NH3, (55:43:2). A 10-cm length of run requires about three hours and provides an excellent separation of the two compounds for identification-differentiation purposes.

Butirosin, a new aminoglycosidic antibiotic complex: isolation and characterization.

Butirosin, a new water-soluble aminoglycosidic antibiotic complex, active against gram-positive and gram-negative bacteria, has been isolated from fermentation filtrates of Bacillus circulans by ion exchange. The complex has been resolved into isomeric A and B components, C(21)H(41)N(5)O(12), by means of Dowex 1 x 1 or Dowex 1 x 2 chromatography. Properties of the free bases and the N, N', N'', N'''-tetraacetyl derivatives of butirosin A and B are given.