Rapid detection of multiple colorant adulteration in Keemun black tea based on hemp spherical AgNPs-SERS.

• A reproducible high sensitivity hemp spherical SERS substrate was prepared. • A simple and rapid method for colorants detection without pretreatment was proposed. • The CARS-PLS model achieved accurate quantification for the 4 adulterated colorants. • A rapid qualitative detection of multiple colorants mixed was achieved. This study synthesized stable and sensitive hemp spherical AgNPs as the SERS substrate for the simultaneous and rapid detection of sunset yellow, lemon yellow, carmine and erythrosine adulteration in black tea. With R6G as the probe molecule, the AgNPs were determined to have satisfactory stability over 60 days with an enhancement factor of 108. The effects of three variable screening methods on model performance were compared. Among them, CARS-PLS exhibited superior performance for the quantification of all the four colorants, with prediction set correlation coefficients of 0.95, 0.97, 0.99 and 0.88, respectively. The differentiation of the mixed colorants was also achieved, with recoveries ranging from 91.87 % to 106.5 % with RSD value <1.97 %, demonstrating the high accuracy and precision of the proposed method. The results indicate that AgNPs-based SERS is an effective method and has substantial potential for application in the identification and quantification of colorant in tea. [ABSTRACT FROM AUTHOR]