Highly sensitive sensing and quantitative detection of sulfate ion with a SERS chip-based on boric acid’s Lewis effect

Based on the Lewis acid’s coordination principle, a surface-enhanced Raman scattering (SERS) chip strategy had been developed for the ultrasensitive quantitation of SO 4 2− . Through the immobilization of silver nanoparticles (Ag NPs) and the construction of the boric acid-based sensing unit, the chip system displayed outstanding merits on the direct sensing of SO 4 2− , e.g., simple operation, ultra-high sensitivity, reproducibility, excellent selectivity and specificity. Moreover, an accurate evaluation was obtained by ratiometric calculations on characteristic peaks (1382 and 1070 cm −1 ) for quantitative detection of SO 4 2− . The detection limit was down to 10 nM. Tap water, beer, and mineral water samples were tested, and high recoveries were achieved (97.12–110.12%). Besides, such SERS chip also displayed strong applicability for the evaluation of SO 3 2− . Therefore, this SERS chip provided a promising idea for the quantification of trace amounts of SO 4 2− and SO 3 2− in the fields of food safety and environmental monitoring. Graphical abstract