红外光谱内标法测定维C药片中抗坏血酸的含量

Determination of ascorbic acid in Vc tablets by internal standard method of FT-IR

选择三水合亚铁氰化钾作为内标物,定量添加到抗坏血酸中,在抗坏血酸质量分数为1%～10%范围内,测得混合物红外光谱中抗坏血酸的测量峰(1 754.1 cm-1)和三水合亚铁氰化钾的内标峰(2 092.7 cm-1)的峰高比(y=hi/hs)与两者质量比(x=mi/ms)有良好的线性关系,其线性回归方程为y=0.566 3x+0.110 4,相关系数r=0.998 6。据此测得维C银翘片和维生素C片样品中抗坏血酸的含量分别为25.8%和72.4%,相对标准偏差为0.7%和0.6%,加标回收率分别为98.1%～106.3%和98.7%～102.7%,测定结果与药典规定的碘量法相近。该法消耗样品少,选择性高,测定结果准确,有应用价值。

Potassium ferrocyanide was added into ascorbic acid samples as internal reference and the mixtures were measured by Fourier transform infrared spectrophotometry （FT-IR）. The peak of ascorbic acid at 1 752. 1 cm-1 was chosen as quantitative peak and the one of potassium ferrocya- nide at 2 092.7 cm-1 was chosen as inside mark quantitative peak. The ratio of two peak＇ s absorbanee （y = hl/ha ） had good linear relationship with their mass ratio （x = mi/ms ） when the mass fraction of ascorbie acid was 1% - 10%. The linear regression equation was y = 0. 566 3x ＋ 0. 110 4 with the correlation coefficient r = 0. 998 6. The contents of ascot- bic acid in the samples of Vc Yinqiao tablets and Vc tablets were 25.8% and 72.4% , the relatively standard deviations were 0. 7% and 0. 6% , the recoveries of the method were 98.1% -106.3% and 98.7% -102.7%.