Determination of Roxithromycin by Spectrophotometry Based on Charge-transfer Reaction with Salicyl Fluorone

OBJECTIVE To determine roxithromycin in capsules and provide the quality control and assurance. METHODS A spectrophotometric method based on the charge-transfer reaction between salicyl fluorone (SAF) and roxithromycin. RESULTS The molar absorptivity of the complex at 516 nm was 5.01×103 L·mol-1·cm-1. Beer's law was obeyed in the range of 33.5-217.6 mg L-1of roxithromycin. The relative standard deviation was 0.64%(n=8). The composition of the complex was found to be 1∶1 by slope ratio and Job’s methods. The mechanism of reaction was investigated, and the average recovery was found to be 100.9%. CONCLUSION The method is simple, quick and accurate for the determination of roxithromycin in capsules.