Reversed phase high performance liquid chromatography and high performance thin layer liquid chromatography methods for simultaneous determination of Theophylline,Guaifenesin and Guaifenesin impurity (Guaiacol) in their bulk powders and in dosage form

Research Abstract

Two simple, rapid chromatographic methods were developed for the simultaneous determination of Theophylline (THP), Guaifenesin (GUI) andGuaifenesin impurity namelyGuaiacol (GUA). The first method is an isocratic RP-HPLC method, where separation ofTHP,GUI and GUAwas achieved on C18 column using methanol: water (containing 0.1% triethylamine): acetonitrile (30:60:10,by volume) as a mobile phase with a flow rate of 0.7mL.min-1and UV detection at 275nm.Theseparationwas achieved at retention times (Rt3.76, 6.76 and 8.79 for THP, GUI and GUA, respectively).The calibration plots were linear over the concentrations range of(2-25µg.mL-1),(2-37µg.mL-1) and (0.5-10µg.mL-1) for THP, GUI and GUA, respectively. The second method isHPTLC method, which was developed usingsilica gelplates 60F254as a stationary phase withethyl acetate :hexane: methanol : ammonia (65:35:10:2, by volume) as a developing system. The densitometricmeasurements were performed at 275nm with good Rfvalues (0.13, 0.35, 0.8) for THP, GUI and GUA, respectively. The calibration plots showed good correlation over the range(0.4-2 µg/band) for both THP and GUI, and (0.4-1.2µg/band) for GUA.The two proposed methods were validated according to ICH guidelines. The results for the two methods were statistically compared to those obtained by a reported HPLC methodand nosignificant difference was found regarding accuracy and precision.

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