Determination of Fluorine Content in Ya'an Tibetan Tea by Ion Chromatography
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 lonPacTM AS11-HC analytical column and Dionex lonPacTM 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 R2 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.
Ya'an Tibetan teaion chromatography methodfluorine contentfluoride ion selective electrode method
万方数据
维普
