Simultaneous determination of salbutamol sulphate, bromhexine hydrochloride and etofylline in pharmaceutical formulations with the use of four rapid derivative spectrophotometric methods.

Four simple, rapid, accurate, precise, reliable and economical spectrophotometric methods have been proposed for simultaneous determination of salbutamol sulphate (SS), bromhexine hydrochloride (BH) and etofylline (ET) in pure and commercial formulations without any prior separation or purification. They were first derivative zero crossing spectrophotometry (method 1), simultaneous equation method (method 2), derivative ratio spectra zero crossing method (method 3) and double divisor ratio spectra derivative method (method 4). The ranges for SS, BH and ET were found to be 1-35 microg mL(-1), 4-40 microg mL(-1) and 5-80 microg mL(-1). For methods 1 and 2, the values of limit of detection (LOD) were 0.2314 microg mL(-1), 0.4865 microg mL(-1) and 0.2766 microg mL(-1) and the values of limit of quantitation (LOQ) were 0.7712 microg mL(-1), 1.6217 microg mL(-1) and 0.9221 microg mL(-1) for SS, BH and ET, respectively. For method 3, LOD values were 0.3297 microg mL(-1), 0.2784 microg mL(-1) and 0.7906 microg mL(-1) and LOQ values were 0.9325 microg mL(-1), 0.9282 microg mL(-1) and 2.6352 microg mL(-1) for SS, BH and ET, respectively. For method 4, LOD values were 0.3161 microg mL(-1), 0.2495 microg mL(-1) and 0.2064 microg mL(-1) and LOQ values were 0.9869 microg mL(-1), 0.8317 microg mL(-1) and 0.6879 microg mL(-1) for SS, BH and ET. The precision values were less then 2% R.S.D. for all four methods. 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.