邻菲啰啉分光光度法测定白砂糖中铁含量

拟建立一种快速、方便、准确可靠的测定白砂糖样品中铁含量的测定方法—邻菲啰啉分光光度法,通过这种方法,可以对白砂糖中的铁进行定量测定,从而确定白砂糖的保质期以及降低其作为原料对饮料企业的影响。样品溶解于水后与盐酸羟胺反应,样液中的Fe~(3+)还原成Fe~(2+),在p H值为3~7的溶液中,邻菲啰啉与Fe~(2+)生成稳定的橙红色络合物;该络合物在波长510 nm有最大吸收值,产物与标准系列比较即可定量。通过实验得出最佳实验条件是最大吸收波长为510 nm,乙酸–乙酸铵缓冲溶液用量为5.0 mL,邻菲啰啉溶液的用量为1.5 mL,显色时间为10~60 min;在此最佳条件下的回归方程y=0.011 8x+0.010 1,r=0.999 0,线性良好;样品平行试验测定结果 RSD均小于5%,该法与火焰原子分光光度法结果间的相对偏差在1%~5%。所建立的邻菲啰啉分光光度法,能够快速、准确地测得白砂糖样品中铁的含量。平行试验以及方法比较均证实该条件下测得的结果精密度、准确性高。

Study on Technology of Phenanthroline Deter Mination of Iron Content in White Granulated Sugar by Spectrophotometry

To establish a rapid, convenient, accurate and reliable method for determination of iron content in white granulated sugar samples——1,10-phenanthroline spectro photometric method. Through this method, can be used for quantitative determination of iron in the sugar, so as to determine the shelf life of white sugar and reduce its impact on the beverage business as a raw material. The samples were dissolved in water, and after the reaction with hydroxylamine hydrochlorider, the sample solution's Fe3+ is reduced to Fe2+, in solution of pH value of 3-7, the 1,10-phenanthroline and Fe2+generating stable orange red complex, the complex has a maximum absorption value at the wavelength of 510 nm, comparison between the product and the standard series can be quantified. The best experimental condition is obtained by the experiment, and the maximum absorption wavelength is 510 nm, Acetic acid - ammonium acetate buffer solution was 5.0 mL, 1,10-phenanthroline solution dosage is 1.5 mL, chromogenic time is 10-60 min. The regression equation under this optimal condition is y=0.011 8x+0.010 1,r=0.999 0,and good linearity. The sample parallel test results RSD are less than 5%,the relative difference between the results of this method and the lfame atomic spectrometry is 1%-5%. The Phenanthroline spectrophotometric method is able to quickly and accurately measure the content of iron in white granulated sugar samples. The results of the parallel test and the comparison of the methods show that the measured results are precise and accurate.