Rapid Determination of Caffeine in Tea by Ultrasonic Extraction
Objective:To optimize the determination of caffeine in tea by GB 5009.139-2014.Method:The ultrasonic extraction method was used,water was used as the extraction agent,magnesium oxide was added to remove impurities,60℃water bath ultrasonic 20 min,separated by high performance liquid chromatography column,and quantified by external standard method.Result:The linear range of caffeine was 6.25～200.00 μg·mL-1,the correlation coefficient was 0.999 92,the detection limit was 2.27 mg·kg-1,the quantitative limit was 7.57 mg·kg-1,the recovery rate was 96.80%～99.04%,and the relative standard deviation of repeatability experiment was less than 2%(n=6).Conclusion:The method is simple,rapid,accurate and reliable,which is suitable for the rapid determination of caffeine in tea.
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