Abstract

Spectrophotometric methods, including one UV and two colorimetric methods are proposed for the determination of budesonide in pure form and in aerosols. The UV method involves preparation of methanolic extract of the drug and its subsequent dilution. Whereas, the colorimetric methods involve reaction of the drug, with tetrazolium blue (TB) In alkaline medium and with phosphomolybdic acid (PMb) in acidic medium to produce purple and blue coloured complexes respectively. Effects of variables such as reagent concentration, alkalinity, time and temperature have been evaluated to permit selection of the most advantageous technique. Beer's law was followed in the concentration range of 1-40 μg/ml (UV), 5-160 μg/ml (TB) and 10-280 μg/ml (PMb). The molar absorptivity at 241.6 nm was 1.56 x 104 mol-1 cm-1 (UV), 530 nm was 4.04 x 103 mol-1cm-1 (TB) and at 715 nm it was 2.38 x 103 mol-1, cm-1 (PMb). The relevant Sandell's sensitivity was 0.02 μg cm-2, 0.1 μg cm-2 and 0.18 μg cm-2 respectively, per 0.001 absorbance unit.