在酸性介质中，2种罗丹明染料[罗丹明6G （Rh6G）和丁基罗丹明B （b-RhB）]可通过静电引力作用与肝素钠（Hep）形成离子缔合物，使2种体系（Hep-Rh6G和Hep-b-RhB）的共振散射信号增强，且增强程度（ΔI）与Hep的质量浓度在定范围内呈线性关系，据此建立了罗丹明染料共振散射光谱法测定Hep含量的方法。试验优化了Hep-Rh6G和Hep-b-RhB体系的分析条件：试剂的加入顺序为罗丹明染料、Hep和缓冲溶液；Hep-Rh6G体系的反应介质为三（羟甲基）氨基甲烷（Tris）-HCl缓冲溶液（pH 5.0），其用量为0.50 mL，1.0×10^-3mol·L^-1 Rh6G溶液的用量为0.50 mL，分析波长为377 nm；Hep-b-RhB体系的反应介质为Britton-Robinson （B-R）缓冲溶液（pH 5.5），用量为0.50 mL，1.0×10^-3mol·L^-1 b-RhB溶液的用量为0.80 mL，分析波长为380 nm。结果表明：Hep-Rh6G和Hep-b-RhB等2种体系的线性范围分别为0.020~2.0 mg·L^-1和0.10~1.6 mg·L^-1，检出限（3s/k）分别为1.10，3.47 μg·L^-1，可见Hep-Rh6G体系的线性范围更宽，检出限更低。因此，采用Hep-Rh6G体系对2个批次的Hep注射液进行了分析，加标回收率分别为96.0%，101%；测定值的相对标准偏差（n=5）分别为4.9%，3.9%。

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.