Sensitive spectrophotometric methods for the determination of amoxycillin, ciprofloxacin and piroxicam in pure and pharmaceutical formulations.

Two simple, sensitive and accurate spectrophotometric methods have been proposed for the determination of amoxycillin (AMX), ciprofloxacin (CPF) and piroxicam (PIR) in pure and pharmaceutical preparations. The methods are based on the measurement of absorbances of tris(o-phenanthroline) iron(II) [method A] and tris (bipyridyl) iron(II) [method B] complexes at 510 and at 522 nm, respectively. Reaction conditions have been optimized to obtain coloured complexes of higher sensitivity and longer stability. The absorbances were found to increase linearly with increase in concentrations of AMX, CPF and PIR which were corroborated by correlation coefficient values. The complexes obeyed Beer's law over the concentration range of 0.06-5.2, 0.04-7.2 and 0.2-6.5 microg ml(-1) for AMX, CPF and PIR, respectively, in method A, and of 0.05-8.5, 0.05-9.0 and 0.05-6.5 microg ml(-1) for AMX, CPF and PIR, respectively, in method B. The developed methods have been successfully applied for the determination of AMX, CPF and PIR in bulk drugs and pharmaceutical formulations. The common excipients and additives did not interfere in their determinations. The results obtained by the proposed methods have been statistically compared by means of Student t-test and by the variance ratio F-test.