NH2-PEG-AuNR-Based Surface-Enhanced Raman Spectroscopy for Rapid Detection of AFB1: Dark Tea Safety Assessment

Abstract There is a risk of aflatoxin B1 (AFB1) contamination during dark tea processing, transportation, and storage. Given the potent carcinogenicity of AFB1, there is an urgent need to develop rapid and sensitive detection methods to address the requirements of tea safety monitoring. A rapid and trace detection method for AFB1 based on surface-enhanced Raman spectroscopy (SERS) using NH2-PEG-AuNRs was established and successfully applied to dark tea. The established method exhibited a linear dynamic range (LDR) for the AFB1 standard solution from 10⁻¹ to 10⁻¹⁷ ng/mL, with a limit of detection (LOD) of 10⁻¹⁷ ng/mL. The partial least-squares (PLS) prediction model achieved an accuracy of 99.36%. For dark tea infusions, the LDR extended from 10⁻¹ to 10⁻⁹ ng/mL, and the LOD of 10⁻⁹ ng/mL. The PLS model achieved an accuracy of 97.43%, and recovery rates ranged from 98.54–102.54%. This establishes a robust methodology for quantifying AFB1 in dark tea.