چکیده (انگلیسی):

Three simple, specific, accurate and precise spectrophotometric methods for the determination of a binary mixture of Azelastine hydrochloride (AZH) and Benzalkonium chloride (BAC) in pure and in their Dosage forms. The methods namely; (A) zero order (D0), (B) ratio difference (RD) and (C)ratio subtraction (RS). In method (A), AZH could be directly determined in the zero order at wave length equals to 284 nm in the range (5.0–50 μg/mL) with good correlation coefficient (0.9994), where no interference from BAC is reported. While BAC was determined by different methods in the range (2.0–30 μg/mL). In method (B) BAC determination depends on dividing the spectrum of the binary mixture by the standard spectrum of 20μg/mL AZH as a divisor, then BAC is determined using the difference between the two wavelengths 262 & 208 nm, we here BAC has absorbances and AZH is constant, the difference = (ΔP262.0-208.0) with good correlation coefficient (0.9994). Finally, in method (C) BAC can be determined by dividing the spectrum of the binary mixture by the standard spectrum of 10 μg/mL AZH as a dvisor, then a constant, which is determined as the mean value of the absorbances in the plateau region (230–300 nm), is subtracted; after multiplication by the divisor we obtain a zero order (D0) original spectrum of BAC at 208.0 nm with good correlation coefficient (0.9992). Accuracy, recovery and the selectivity of the developed methods are applied on the laboratory prepared mixtures, standard addition technique and pharmaceutical dosage form. The obtained results for the suggested methods are statistically compared with the reported HPLC one using student’s-t and F-ratio tests, showing that the two methods are accurate and precise.