不完全抑制电导检测离子色谱法测定饮料中的苹果酸

Determination of Malic Acid by Incompleted Suppressed Conductivity Detection in Ion Chromatography

采用一种抑制型离子色谱检测技术——不完全抑制电导检测,以0.75 mmol/LNa_2SO_4+NaOH(pH=11.5)为淋洗液对弱酸根离子如苹果酸、酒石酸等进行了测定.得到苹果酸、酒石酸的检测限分别为1.31 mg/L、3.04 mg/L;在200mg/L以下相关系数分别为0.9998、0.9999;各离子峰高的相对标准偏差(RSD)分别为0.57%、1.60%(n=7).回收率为97.7%～104%.常见的强酸离子不干扰测定.用这种方法测定了饮料中的苹果酸,结果较满意.

Malic acid in soft drinks was determined by ion chromatogaphy using incompleted (indirect) suppressed conductivity detection. The mobile phase used contained 0.75 mmol/L Na2SO4 + NaOH(pH = 11.5). Trie detection limits of malic acid and tartaric acid were 1.31 mg/L, 3.04 mg/L respectively. The correlation coefficients of standard curves for malic acid and tartaric acid were 0.9998 and 0.9999 respectively in the range of 0-200 mg/L. RSDs for peak height were 0. 6% , 1. 6% (n = 7) respectively. The recoveries were 97.7% -104.0% . The common inorganic ions did not interfere.