An indirect atomic absorption spectrometric determination of ciprofloxacin, amoxycillin and diclofenac sodium in pharmaceutical formulations

A highly sensitive indirect atomic absorption spectrophotometric (AAS) method has been developed for the determination of very low concentrations of ciprofloxacin, amoxycillin and diclofenac sodium. The method is based on the oxidation of these drugs with iron(III). The excess of iron(III) was extracted into diethyl ether and then the iron(II) in the aqueous layer was aspirated into an air-acetylene flame and determined by AAS. The linear concentration ranges were 25-400, 50-500 and 60-600 ng ml(-1) for ciprofloxacin, amoxycillin and diclofenac sodium, respectively. The results were statistically compared with the official method using t- and f-test at p < 0.05. There were insignificant interferences from most of the excipients present. The intra- and inter-day assay coefficients of variation were less than 6.1 % and the recoveries ranged from 95 to 103 %. The method was applied for the analysis of these drug substances in their commercial pharmaceutical formulations.