COLORIMETRIC AND ATOMIC ABSORPTION SPECTROMETRIC METHODS FOR THE DETERMINATION OF NEFAZODONE HYDROCHLORIDE AND TRAZODONE HYDROCHLORIDE IN PURE FORM AND PHARMACEUTICAL PREPARATIONS

Two sensitive methods, colorimetric and atomic absorption spectrometric (AAS) were developed for the determination of nefazodone HCl (I) and trazodone HCl (II). The methods are based on the formation of ternary complex between the cited drugs and molybdenum(V) thiocyanate in acid medium with the production of an orange red color followed by extraction with methylene chloride. The complex showed absorption maximum at 472 nm with apparent molar absorptivity 1.46 x 10⁴ and 0.64 x 10⁴ L mol^-1 cm for I and II, respectively. Beer's law was obeyed in the range 2.5-32.5 and 2.5-30.0 µg ml^-1 for I and II, respectively. The residue remained after evaporation of methylene chloride was dissolved in HCl and used for determination of molybdenum content by AAS as a direct method for the determination of the cited drugs. Results obtained by applying the proposed methods showed good recoveries of 99.9 ± 1.3% and 99.4 + 1.6% for colorimetric method, whereas using AAS the recoveries were 98.7 ±1.3% and 98.6 ± 1.8% for I and II, respectively. Results obtained by both methods showed good agreement with those of the official and reference methods. The developed methods were applied for determination of these drugs in their pharmaceutical formulations.