离子色谱法测定雅安藏茶中的氟含量

Determination of Fluorine Content in Ya'an Tibetan Tea by Ion Chromatography

雅安藏茶是一种地方特色性黑茶,原料的成熟度较高。文章建立了采用离子色谱测定雅安藏茶中氟含量的方法,即采用Dionex IonPac^(TM)AS11-HC分析柱和Dionex IonPac^(TM)AG11-HC保护柱,柱温为30℃,以KOH淋洗液梯度洗脱,梯度洗脱程序:0~20 min,KOH浓度为0.55 mmol/L;20~80 min,KOH浓度为0.55~55 mmol/L;80~93 min,KOH浓度为55 mmol/L;93~95 min,KOH浓度为0.55 mmol/L,流速为0.85 mL/min,电导检测器检测。在该条件下奎尼酸、乳酸、乙酸等低分子质量有机酸与氟离子可得到较好的分离。方法学考察结果表明,氟离子在0.00~1.00μg/mL的浓度范围内具有良好的线性关系,相关系数R^(2)为0.9998,检出限为0.0015 mg/g,定量限为0.0050 mg/g。精密度、重复性、回收率表现良好,茶样提取液在24 h内稳定。采用氟离子选择电极法与离子色谱法测定20个雅安藏茶样品氟含量的相对误差在0.6%~5.1%之间。该研究可促进对雅安藏茶的质量控制,为相关检测方法标准的制定和修订提供参考。

Ya’an Tibetan tea is a local characteristic dark tea with high maturity of raw materials.A method for determining the fluoride content in Ya’an Tibetan tea using ion chromatography was established.The method employed Dionex IonPac^(TM) AS11-HC analytical column and Dionex IonPac^(TM) AG11-HC protective column were with a column temperature of 30 ℃ and gradient elution of KOH eluent.The gradient elution program was as follow:0–20 min,KOH concentration was 0.55 mmol/L;20–80 min,KOH concentration was 0.55–55 mmol/L;80–93 min,KOH concentration was 55 mmol/L;93–95 min,KOH concentration was 0.55 mmol/L.The flow rate was 0.85 mL/min,and the conductivity detector was used for detection.Under these conditions,low molecular weight organic acids such as quinic acid,lactic acid,and acetic acid can be effectively separated from fluoride ions.The methodological examination results indicated that the fluoride ions had a good linear relationship within the concentration range from 0.00 to 1.00 μg/mL,and the correlation coefficient R^(2) was 0.9998.The limit of detection was 0.0015 mg/g,and the limit of quantitative was 0.0050 mg/g.The precision,repeatability,and recovery rate were good,and the tea extract remaining stable within 24 hours.The relative error of using fluoride ion selective electrode method and ion chromatography method to determine the fluoride content of 20 samples of Ya’an Tibetan tea ranged from 0.6% to 5.1%.The study can promote the quality control of Ya’an Tibetan tea and provide reference for the revision of relevant testing method standards.