Abstract: In pH 3.5 HAc-NaAc buffer solution, furosemide reacted with Ag (I) to form a 1: 1 chelate. In this case, the intensities of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) spectra were enhanced greatly and the new scattering spectra appeared. The maximum RRS, SOS and FDS wavelength was located at 310, 584, 330 nm, respectively. The intensities of RRS, SOS and FDS were directly proportional to the concentration of furosemide in a certain range and the detection limit was 1.3 ng/mL, 3.0 ng/mL and 6.9 ng/mL, respectively. In addition, the optimum conditions and the influences of coexisting substances were tested by RRS method and the results showed that this method had good selectivity. Therefore, a new simple, rapid, and sensitive light scattering method has been developed for the determination of furosemide in tablets and urine samples. In addition, the reaction mechanism and the reasons for the enhancement of scattering spectra were discussed.had been investigated. In addition, the optimum conditions of these reactions and the influences of coexisting substances were tested by RRS method and the results showed that this method had good selectivity. Therefore, a highly sensitive, simple and quick method has been developed for the determination of furosemide. The method can be applied satisfactorily to the determination of furosemide in tablets and urine samples. In addition, the reaction mechanism and the reasons for the enhancement of scattering spectra were discussed.

Key words: furosemide, Ag (I), resonance rayleigh scattering, second-order scattering, frequency doubling scattering