超分子双波长共振光散射法测定半胱氨酸含量

对半胱氨酸-孔雀石绿体系的反应条件进行优化，建立孔雀石绿单波长、双波长共振光散射光谱法检测半胱氨酸的新方法。结果表明：在硼砂-氢氧化钠缓冲溶液中，孔雀石绿与硼酸结合产生共振光散射，在波长285、338 nm处有2 个较强烈的共振光散射峰；加入半胱氨酸后，共振光散射更加强烈，且共振光散射强度随着半胱氨酸浓度增加而增强。在波长285、338 nm处，半胱氨酸在0.10～0.60 mg/L范围内与体系共振散射强度差值（ΔI）呈线性关系，检出限分别为10.7、13.3 μg/L；双波长叠加法的检出限为3.23 μg/L。本方法可应用于半胱氨酸护肝胶囊和酱油中半胱氨酸的含量测定，测定值的相对标准偏差（n＝6）均在3%以内，符合定量分析的要求。

Determination of Cysteine Content by Supramolecular Polymer-Based Dual Wavelength Resonance Light Scattering Spectroscopy

A new method for the determination of cysteine by single-wavelength and dual-wavelength resonance light scattering spectroscopy with malachite green was established. The reaction conditions of the cysteine-malachite green system were optimized. The results showed that in borax-sodium hydroxide buffer solution, malachite green combined with boric acid to produce resonance light scattering, and two strong resonance light scattering peaks appeared at wavelengths of 285 and 338 nm; after adding cysteine, the resonance light scattering became more intense, and the intensity of resonance light scattering increased with the increase of cysteine concentration. The difference between the intensity of resonance light scattering at 285 and 338 nm displayed a linear relationship with cysteine concentration in the range of 0.10–0.60 mg/L, with limits of detection of 10.7 and 13.3 μg/L, respectively. The limit of detection of the dual-wavelength superposition method was 3.23 μg/L. When applying this method to detect cysteine in hepatoprotective agent and soy sauce, the relative standard deviations (n = 6) were within 3%, which meets the requirements of quantitative analysis.