Spectrophotometric determination of methoxamine hydrochloride using NQS and brucine metaperiodate

摘要

Two simple and sensitive extractive visible spectro photometric methods (A and B) for the assay of Methoxamine hydrochloride (MHC), in pure and pharmaceutical formulations, The method-A is based on the condensation reaction of MHC reduced with sodium 1,2-naphthaquinone-4-sulfonate (NQS) in an alkaline medium to form an orange-red colored Schiff's base of maximum absorption peak (λmax) at 445 nm,The method-B is based on the formation coloured complexes with the dimethoxy benzene nucleus of brucine is attacked by Per Iodate with the formation of o-quinone (bruciquinone) which in turn undergoes nucleophilic attack on the most electron rich position of the coupler i.e., proton bearing amino group (primary amine), to give 1-mono substituted bruciquinone derivative. The reaction mechanism in both methods were discussed. The absorbance of colored complex is gound at 520nm. Beer's law is obeyed in the concentration range 5-30 μg/Ml,50-500 μg/Ml, the molar absorptivity values are1.9652 x 105, 1.4797 x 104L/mol.cm, Sandell sensitivity are1.2605 x 10-3,1.6741x10-2ng/cm2 (For methods A&B).The methods proposed gave reproducible results with the percentage recoveries in the formulations found to be 99.800 to 99.772 (Method A) and 99.812 to 99.749 (Method B).