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摘 要 根据C2O42-与Ti3+发生螯合反应形成黄色配合物，溶液颜色随C2O42-浓度的增加而加深，吸光度随C2O42-浓度的增加而呈线性增加的原理，建立了三氯化钛分光光度法测定果蔬中草酸含量的方法。先通过分光光度计测在不同的入射光下的配合物溶液（草酸与三氯化钛反应产物）吸光度，找出最大的吸收波长，在其对应波长下，测定各种数据，分析本测定方法的影响因素，以找出最佳的测定条件和适用范围。测定最佳条件为pH1.5~1.7，检测光波长400nm，显色时间为1min之内，测量范围0.5*10-3~4*10-3mol/L，草酸的检出下限为0.25*10-3mol/L。结果表明，测定平均回收率为99.6%；而且具有较好的重现性。[1]43797
毕业论文关键词 果蔬 草酸 三氯化钛 分光光度法
Determination of Oxalic Acid in Vegetables
Abstract:According to the theory that the chelate reaction with C2O42- and Ti3+ result in the yellow complex,the color of the solution become darker with the increase of the concentration of C2O42-,and the the concentration of C2O42- is increased linearly to the absorbance, the titanium trichloride spectrophotometry method is eastablished for thedetermination of oxalic acid content in fruit and vegetable. Firstly, using spectrophotometer measuring products of the reaction of oxalic acid and titanium trichloride, the absorbance is measured at different incident light complex solution to find out the maximum absorption wavelength. Various sourses are collected by the corresponding wavelength, and the influencing factorsof the determination method is analysed to find the optimum measuring conditions and scope. The optimum measuring conditions included pH1.5~1.7, detection wavelength of 400nm, significant time for one minute, measuring range 0.5*10-3~4*10-3mol/L, oxalic acid detection limit for 0.25*10-3mol/L.The results show that the determination of the average recovery rate was 99.6%; and the method is reproducibile.
Key words: vegetables;oxalic acid;TiCl3;spectrophotometry
目录
1 前言 4
1.1 背景 4
1.2.1 滴定法 5
1.2.2 离子色谱法 5
1.2.3 高效液相色谱法 6
1.2.4 荧光分析法 6
1.2.5 比色法 6
1.2.6 毛细管电泳分析法 7
1.3 本课题设计的分析方法 8
1.3.1 分光光度法 8
1.3.2 本课题的基本内容 8
1.3.3 分析方法 8
2 仪器与试剂 9
2.1 仪器 9
2.2 试剂 9
2.3 样品 10
3 实验内容 10
3.1 反应物最大吸收波长的确定方法 10
3.2 溶液酸度的确定方法 10
3.3 显色时间对测定的影响 10
3.4 杂酸的影响 10
3.5 草酸标准曲线的建立方法 11
3.6 样品预处理方法 10
3.7 样品中草酸含量测定方法