茶叶中茶氨酸的国标检测方法改进研究

Research on improvement of national standard detection method for theanine in tea

基于国家标准GB/T 23193-2017《茶叶中茶氨酸的测定高效液相色谱法》的测定方法,研究建立了快速准确地测定茶叶中茶氨酸含量的高效液相色谱检测方法,茶叶样品通过超声提取15 min(超声功率为500 W)和离心15 min(5000 r/min),能快速完成样品制备。采用Spursil C18高效液相色谱柱(粒径5μm,250 mm x 4.6 mm),流速为1.0 mL/min,柱温为35℃,进样量为20μL,检测波长为210 nm,以纯水为流动相,等度洗脱,茶氨酸在0.00~0.40 mg/mL范围内线性良好,在0.14~0.21 mg/mL的加标范围内,平均回收率为99.1%~100.5%,重复性试验的相对标准偏差(RSD)为2.90%,精密度试验的RSD为1.82%,稳定性实验的RSD为1.53%,样品提取液在20 h内稳定。该改进方法简便、快速,精密度好、准确度高,重复性和稳定性良好,可用于对茶叶中茶氨酸含量的快速测定。

Based on the determination method of national standard GB/T 23193-2017"Determination of theanine in tea by high-performance liquid chromatography",a rapid and accurate detection method for theanine content in tea by high-performance liquid chromatography was established.Tea samples were prepared by ultrasonic extraction in 15 minutes at ultrasonic power of 500 W and centrifugation for 15 minutes(5000 r/min).Then samples were separated by a Spursil C18 high-performance liquid chromatography column(particle size 5μm,250 mm x 4.6 mm)at the condition of 1.0 mL/minflow rate,35℃column temperature and 20μL injection volume.The detection wavelength was 210 nm,pure water was the mobile phase at isocratic elution.The linearity of theanine showed good in the range of 0.00~0.40 mg/mL with the average recovery rate of 99.1%~100.5%in the additional standard range of 0.14~0.21 mg/mL.The relative standard deviation(RSD)of the repeatability test was 2.90%,RSD of the precision test was 1.82%,and RSD of the stability test was 1.53%.The sample extract was stable within 20 hours.This improved method operated easily and quickly,and result was with high precision and accuracy,with good repeatability and stability.It can be used for the rapid determination of theanine in tea.