Determination of Heparin Sodium in Heparin Sodium Injection by Resonance Scattering Spectrometry Based on Rhodamine Dyes

In an acidic medium, 2 ion-association complexes were formed between rhodamine dyes of rhodamine 6G (Rh6G) and butylrhodamine B (b-RhB) and heparin sodium (Hep) by electrostatic attraction, which enhanced the resonance scattering (RS) signal intensity of the two systems (Hep-Rh6G and Hep-b-RhB), and the enhanced RS intensity (ΔI) was proportional to mass concentration of Hep in deinite ranges for the above two systems. Based on the fact, RS spectrometry was applied to the determination of Hep by rhodamine dyes. The optimized conditions for the 2 systems found were as follows:the order of adding reagents was rhodamine dye, Hep and buffer solution, respectively; for Hep-Rh6G system, the amount of Tris-HCl buffer solution (pH 5.0) was 0.50 mL, the amount of 1.0×10^-3mol·L^-1 Rh6G solution was 0.50 mL, and the measured wavelength was 377 nm; for the Hep-b-RhB system, the amount of B-R buffer solution (pH 5.5) was 0.50 mL, the amount of 1.0×10^-3mol·L^-1 b-RhB solution was 0.80 mL, and the measured wavelength was 380 nm. The results showed that linearity ranges of Hep for Hep-Rh6G and Hep-b-RhB systems were found in the ranges of 0.020-2.0 mg·L^-1 and 0.10-1.6 mg·L^-1, with detection limits (3s/k) of 1.10, 3.47 μg·L^-1, respectively. The Hep-Rh6G system had a wider linearity range and a lower detection limit; therefore, this system was applied to the analysis for the 2 batches of heparin sodium injection, giving results of recovery by standard addition method of 96.0%, 101%, and RSDs (n=5) of the determined values were 4.9%, 3.9%, respectively.