Determination of Furosemide in Drug by Rayleigh Light Scattering Quenching with Malachite Green

The sample (0-4.0 mg) was placed into 10 mL colorimetric tube, and trihydroxymethyl aminomethane-HCl buffer solution of pH 7.64 (1.0 mL) and 1.00×10^-4mol·L^-1 malachite green solution (2.00 mL) were added. The obtained solution was diluted to 10 mL and reacted for 10 min. Furosemide reacted with malachite green to form an ionic association complexes, which led system's Rayleigh light scattering (RLS) had a quenched effect. The maximum RLS peak was located at 370 nm. Linear relationship between RLS quenched degree (ΔI_RLS) and mass concentration of furosemide was found in the range of 0.006-0.40 mg·L^-1, with detection limit (3s/k) of 0.005 4 mg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 98.7%-102%, with RSDs (n=6) all less than 3.0%.