猪屎豆抗氧化活性成分的提取及活性测定体系的优化

[目的]研究猪屎豆（Crotalaria mucronata Desv.）乙醇提取物的抗氧化活性。[方法]采用超声波辅助乙醇提取法提取猪屎豆抗氧化活性成分,用H2O2-鲁米诺化学发光体系测定清除羟自由基（·OH）的效率。并对测定体系进行优化。[结果]在料液比为3.6∶1,乙醇体积分数为70%,提取时间为30min,提取温度为80℃,猪屎豆乙醇提取物对·OH的清除效果最佳。清除率测定体系中,H2O2浓度为0.60%和Luminol浓度为1.00×10-4mol/L时测定结果较准确。[结论]猪屎豆乙醇提取物对·OH有很好的清除作用。     

流动注射—化学发光法测定蔬菜中的微量亚硝酸盐研究

利用鲁米诺—铁氰化钾—尿酸化学发光体系,在酸性介质中,亚硝酸盐氧化亚铁氰化钾为铁氰化钾,建立了间接测定微量亚硝酸盐的方法。讨论了酸度、反应物浓度、干扰离子等因素的影响,检出限达5.0×10-5mg/L,线性范围在0.001~10 mg/L,加标回收率在97.5%~104%之间,RSD≤3.6%,该方法尤其适合于较低微量亚硝酸盐的测定,可用于各种蔬菜中微量亚硝酸盐的测定。     

化学发光法测定水和食品中痕量亚硝酸根

基于在碱性介质中,亚硝酸根离子增强鲁米诺—碘化钾偶合化学发光体系发光强度这一现象,采用静态化学发光法,建立了测定亚硝酸根的化学发光方法。运用单因素和正交实验对反应条件进行优化。在选定的最佳条件下,该方法的检出限为3.3×10-11g/mL,回收率为99.15%￣101.13%。该方法用于实际样品水和罐头食品中亚硝酸根的检测,结果令人满意。     

流动注射—化学发光法测定蔬菜中的微量亚硝酸盐研究

利用鲁米诺—铁氰化钾—尿酸化学发光体系,在酸性介质中,亚硝酸盐氧化亚铁氰化钾为铁氰化钾,建立了间接测定微量亚硝酸盐的方法。讨论了酸度、反应物浓度、干扰离子等因素的影响,检出限达5.0×10-5mg/L,线性范围在0.001￣10mg/L,加标回收率在97.5%￣104%之间,RSD≤3.6%,该方法尤其适合于较低微量亚硝酸盐的测定,可用于各种蔬菜中微量亚硝酸盐的测定。     

A modified chemiluminescence method for hydrogen peroxide determination in apple fruit tissues

Hydrogen peroxide (H₂O₂) is one of the important by-products produced by plant and fruit tissues during normal metabolism as well as under stress conditions. Evidence suggests that it is actively involved in many physiological activities in plants, including ripening, senescence and the development of disorders. Quantitative measurement of H₂O₂ in fruit has been a challenge due to variations in methodologies, and their sensitivities and interferences present in plant samples. Among the currently used methodologies, chemiluminescence (CL) is one of the most promising, due to its high specificity and sensitivity. However, direct application of CL methods developed for leaf analysis is not suitable for fruit, especially fruit peel tissues, possibly due to interfering compounds in fruit tissues. In this study, evaluation of the efficiency of removal of interfering compounds by PVP, PVPP and activated charcoal revealed that the PVPP is the most effective compound to remove the interference. This modified protocol can measure H₂O₂ content in apple peel and flesh tissues. ‘Red Delicious’ apple peel and flesh tissues were measured with amount of 1.48 and 1.03 μmol/g FW, respectively. The established protocol can also be used for a wide variety of tissues in addition to apple fruit, including strawberry tissues (fruit, calyx and leaves) and spinach leaves. This protocol was applied to determine the H₂O₂ concentration in 1-MCP and DPA treated apples after 5 months of storage, but no significant difference in H₂O₂ in those samples was found. Direct comparison of CL with a commercial hydrogen peroxide measurement OXIS kit was also made. The challenges to accurately assay H₂O₂ in fruit/plant tissue were discussed.     

过氧化氢-鲁米诺流动注射化学发光法测定甲基毒死蜱

[目的]建立测定甲基毒死蜱的新方法。[方法]在NaOH介质中,过氧化氢氧化鲁米诺产生化学发光,甲基毒死蜱对该发光反应有增强作用且发光强度-与甲基毒死蜱的浓度有较好的线性关系,基于此性质,用过氧化氢-鲁米诺流动注射化学发光法测定甲基毒死蜱。[结果]在该试验确定的优化条件下,测定甲基毒死蜱的线性范围为3×10^-7～3×10^-5g／ml,检出限为3．8×10^-6g／ml,对浓度1×10^-6g／ml的甲基毒死蜱进行11次平行测定,其RSD为2．83％。[结论]研究了体系的化学发光光谱及紫外可见光谱特性,提出了发光反应可能的机理。将该法用于合成样品中甲基毒死蜱的测定,获得满意结果。