Analysis of pharmaceutical dosage forms for oxfendazole: II. Simultaneous liquid chromatographic determination of oxfendazole and trichlorfon in equine paste.
A reverse phase liquid chromatographic procedure is described for the simultaneous determination of oxfendazole [2-(methoxycarbonylamino)-5-phenylsulfinylbenzimidazole] and trichlorfon [(2,2,2-trichloro-1-hydroxyethyl)phosphonic acid dimethyl ester] in equine paste. The sample is extracted by sonication in methanol. Insoluble excipients are removed by centrifugation and an aliquot plus internal standard are diluted with dilution solvent (water-acetonitrile-phosphoric acid, 80 + 20 + 1). The samples are filtered and injected onto a Partisil-5 ODS-3 column with acetonitrile-0.01 M phosphate buffer pH 6.0 (20 + 80) as mobile phase. Method specificity is confirmed using an absorbance rationing technique. The method yields mean recoveries of 100.9 and 100.0% for trichlorfon and oxfendazole, respectively. Dependence of chromatographic performance characteristics on mobile phase organic content, pH, and buffer concentration is also reported.
D000818:Animals; D000871:Anthelmintics / Q000032:analysis*; D001562:Benzimidazoles / Q000032:analysis*; D002853:Chromatography, Liquid; D006736:Horses; D006863:Hydrogen-Ion Concentration; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet; D014236:Trichlorfon / Q000032:analysis*
D000871:Anthelmintics; D001562:Benzimidazoles; D012997:Solvents; D014236:Trichlorfon; C011030:oxfendazole