漫反射傅里叶变换红外光谱法测定维生素C制剂中抗坏血酸的含量

Determination of Ascorbic Acid in Vitamin C Tablet by Diffuse Reflectance Fourier Transform Infrared Spectroscopy

采用漫反射傅里叶变换红外光谱法（DRIFTS）测定维生素C制剂中抗坏血酸的含量。选择合适的分析峰1660～l680cm^-1,可排除其它成分的影响，吸光度与抗坏血酸的浓度呈良好线性关系。以镜面为背景，以75μm筛过筛后的KBr为稀释剂，用DRIFTS法分别测定了3种市售维生素C制剂中的抗坏血酸含量，测定结果分别为75．60％，9．80％，6．72％；相对标准偏差（n=6）分别为6．6％，4．9％，8．2％，与碘量法测定结果接近。样品加标回收率为94．0％。DRIFTS法测定维生素c中的抗坏血酸方法简便、准确，无试剂消耗，无废液产生，是非破坏和非污染的绿色分析方法。但其测定结果的精密度不如碘量法，而且其测定结果的准确程度受样品的性状限制，对于白色粉末或可研磨为粉末的样品分析结果准确度较高。

Ascorbic acid in vitamin C tablet was determined by DRIFTS. The characteristic absorption peak range 1 660-1 680 cm^-1 was selected as the analytical peak to eliminate the interference of subsidiary. Linear relationship between the concentration of ascorbic acid and the absorbance kept very well. The ascorbic acid contents in three vitamin C tablets in market were determined by DRIFTS. The mirror was used as the background, and smaples were diluented by KBr powder sieved with 75 p, m sieve. The results of the three samples by the DRIFTS were 75.60%, 9.80%, 6.72%; RSD （ n=6 ） were 6.6%,4.9%, 8.2%, respectively, which were consistent with the Iodometric method. The average recovery of ascorbic acid was 94.0%. The DRIFTS method is rapid, accurate and without consumption of reagents and solutions. It is a non- destructive and non-polluting green ananlysis method. But the precision of DRIFTS method is poorer than iodine quantity method, and the accuracy of the determination results is restricted by the sample＇ s state. The determination results for the white powder have good accuracy.