A novel approach for tea polyphenol detection based on flow batch analysis system in conjunction with diazotization coupling reaction

Tea polyphenols are a general term for the total phenolic compounds in tea. Tea polyphenols play a crucial role in the quality of tea. Rapid detection of tea polyphenols is essential for tea harvesting and breeding. In this paper, a rapid method for the detection of tea polyphenols is presented based on diazotization coupling (DC) reaction and flow batch analysis system (FBAS). The tea polyphenols detection based on DC reaction can avoid interference from non-phenolic substances and improve detection accuracy. Meanwhile, FBAS for sample injection can shorten the analysis time, reduce the reagent consumption and improve the sensitivity. Experimental results demonstrate that absorbance values exhibit linearity with gallic acid concentrations in the range of 5 to 60 μg/mL, with a linear equation of y = 0.0279x + 0.0613 (R 2 = 0.9993) and a limit of detection (LOD) of 0.215 μg/mL (S/N=3). The method was applied to the detection of tea polyphenols in tea samples, with relative standard deviations (RSD) ranging from 0.326% to 0.659%. The DC-FBAS method has a high potential application with the requirements of portable, cost-effective, and highly precise on-site tea polyphenols detection.