Transmission FTIR derivative spectroscopy for estimation of furosemide in raw material and tablet dosage form

A Fourier transform infrared derivative spectroscopy(FTIR-DS)method has been developed for determining furosemide(FUR)in pharmaceutical solid dosage form.The method involves the extraction of FUR from tablets with N,N-dimethylformamide by sonication and direct measurement in liquid phase mode using a reduced path length cell.In general,the spectra were measured in transmission mode and the equipment was configured to collect a spectrum at 4 cm^(-1) resolution and a 13 s collection time(10 scans co-added).The spectra were collected between 1400 cm^(-1) and 450 cm^(-1).Derivative spectroscopy was used for data processing and quantitative measurement using the peak area of the second order spectrum of the major spectral band found at 1165 cm^(-1)(SO_(2) stretching of FUR)with baseline correction.The method fulfilled most validation requirements in the 2 mg/mL and 20 mg/mL range,with a 0.9998 coefficient of determination obtained by simple calibration model,and a general coefficient of variation <2%.The mean recovery for the proposed assay method resulted within the(100±3)%over the 80%–120% range of the target concentration.The results agree with a pharmacopoeial method and,therefore,could be considered interchangeable.