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

Based on the Lewis acid's coordination principle, a surface-enhanced Raman scattering (SERS) chip strategy had been developed for the ultrasensitive quantitation of SO₄^2-. 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 SO₄^2-, 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 SO₄^2-. 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 SO₃^2-. Therefore, this SERS chip provided a promising idea for the quantification of trace amounts of SO₄^2- and SO₃^2- in the fields of food safety and environmental monitoring.