间接离子色谱法测定花茶中二氧化硫含量的研究

Determination of Sulfur Dioxide in Herb Tea by Indirect Ion Chromatography

【目的】建立花茶中二氧化硫含量的离子色谱分析方法,为茶叶中二氧化硫的分析检测提供参考。【方法】将花茶样品加酸后采用水蒸气蒸馏,用过氧化氢溶液吸收蒸馏释放出的二氧化硫,经0.22μm微孔滤膜过滤后,采用AG11-HC型保护柱和AS11-HC型分离柱进行分离,在离子色谱—电导检测模式下,对KOH淋洗液的浓度和流速进行优化。【结果】在KOH浓度为30.00 mmol·L^(-1),流速为1.00 m L·min-1条件下,硫酸根标准溶液浓度在3.60~36.00 mg·L^(-1)内具有良好的线性关系(r=0.9998),检出限为0.06 mg·L^(-1),加标回收率为80.89%~93.61%,测定值的相对标准偏差(n=3)为2.45%~4.85%。【结论】加酸蒸馏—过氧化氢氧化间接离子色谱法操作简便,灵敏度高,可用于花茶中二氧化硫的含量测定。

【Objective】To provide a method reference for the analysis and determination standards of sulfur dioxide in herb tea,a test method of sulfur dioxide by ion chromatography was established.【Method】Samples of herb tea were distilled under acidic conditions,and the sulfur dioxide produced was absorbed into hydrogen peroxide solution,and then was oxidized into sulfate ion. The solution was filtered with 0. 22μm filtering menbrane,and the filtrate was separated on AG11-HC protective column and AS11-HC separation column. Chromatographic conditions of the eluent concentration and flow rate were optimized with ion chromatography-conductance detection mode.【Result】The optimum chromatographic condition was using 30. 00 mmol·L-（-1） KOH as the eluent at a flow rate of 1. 00 m L·min-1. Under this condition,sulfate standard curve correlation was good in the range from 3. 60 mg·L-（-1） to 36. 00 mg·L-（-1）（r = 0. 9998）,the detection limit of the method was 0. 06 mg·L-（-1）. Values of recovery rate were in the range of 80. 89 %-93. 61 %,and values of RSD＇s（ n = 3） were found in the range of 2. 45 %-4. 85 %. 【Conclusion】The indirect method by ion chromatography is simple and sensitive,which is suitable for the determination of sulfur dioxide in herb tea.