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    分光光度法测定4种芒果中的铁含量

    Spectrophotometric Determination of Iron in 4 Varieties of Mangoes

    • 摘要: 用高氯酸-硝酸(1+4)混合酸湿法消解处理一定量芒果样品(鸡心芒、台农芒、金煌芒或黄金大芒),蒸至近干,加水定容至25 mL。分取1.50 mL样品溶液,加100 g·L-1盐酸羟胺溶液1.00 mL将铁(Ⅲ)还原至二价。基于亚铁离子与铁氰化钾之间生成蓝色化合物的反应,用分光光度法测定样品溶液中的铁含量。铁的质量浓度在0.04~10.09 mg·L-1范围内与其吸光度呈线性关系,检出限(3S/N)为0.02 mg·L-1。加标回收率在98.7%~100%之间,测定值的相对标准偏差(n=6)均小于0.60%。几种芒果中微量铁元素含量的多少依次为台农芒、黄金大芒、金煌芒、鸡心芒。

       

      Abstract: The sample of each of the 4 varieties of mangoes, i.e. Heart-shaped mango, Tainong mango, Jinhuang mango and Golden mango was digested with a mixed acid of perchloric acid and nitric acid (1+4). The solution was evaporated to near dryness, and the residue was taken up with water and diluted to 25 mL with water. An aliquot of 1.50 mL of the solution was taken, and 1.00 mL of 100 g·L-1 NH2OH·HCl solution was added to reduce Fe(Ⅲ) ion to Fe(Ⅱ) ion, which was the determined by spectrophotometry. Iron in sample solution was determined by spectrophotometry based on the formation of blue color by the reaction between Fe2+ ion and potassium ferricyanide. Linear relationship between values of absorbance and mass concentration of iron was obtained in the range of 0.04-10.09 mg·L-1, with detection limit (3S/N) of 0.02 mg·L-1. Values of recovery found by standard addition method were in the range of 98.7%-100%, and values of RSD′s (n=6) found were less than 0.60%. Iron contents of the 4 varieties of mangoes were found successively increased from Heart-shaped mango, Jinhuang mango, Golden mango to Tainong mango.

       

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