ESTIMATION OF IPRATROPIUM BROMIDE BY EXTRACTION FREE SPECTRO-PHOTOMETRIC METHOD USING SULPHONAPTHALEIN DYE

The present paper portrays a simple, rapid, nonextractive spectrophotometric method for the estimation of an anticholinergic drug, Ipratropium Bromide. The method is based on the formation of an instantaneous stable yellow colored ion pair complex of drug with a chloroformic solution of reagent Bromophenol Blue (BPB) which shows absorption maxima at 416 nm. Job’s plot of continuous variation affirmed the development of 1:1 complex between drug and reagent. The optical parameters were optimized, and the calibration curve was found to be linear in the range of 10 µgmL^-1 to 80 µgmL^-1. The detection limit was found to be 2.75 μg mL^-1 with Sandell’s sensitivity 0.083 μgcm^-2. Stability constant (log K_f) was calculated as 6.6. Molar absorptivity was found to be 4.29 × 10³ L mol^-1 cm^-1 with Gibb’s free energy change of – 3.1 × 10⁴ kJ mol^-1. The method was validated as per ICH guidelines and had many advantages like low detection limits, high sensitivity and not requiring adjustment of critical conditions, thus paving the way for the application of the proposed methods in routine quality control evaluation.