Development of a Sensitive SERS Method for Label-Free Detection of Hexavalent Chromium in Tea Using Carbimazole Redox Reaction

Abstract

Tea plants absorb chromium-contaminated soil and water and accumulate in tea leaves. Hexavalent chromium (Cr6+) is a very toxic heavy metal; excessive intake of tea containing Cr6+ can cause serious harm to human health. A reliable and sensitive surface-enhanced Raman spectroscopy (SERS) method was developed using Au@Ag nanoparticles as an enhanced substrate for the determination of Cr6+ in tea. The Au@AgNPs coated with carbimazole showed a highly selective reaction to Cr6+ in tea samples through a redox reaction between Cr6+ and carbimazole. The Cr6+ in the contaminated tea sample reacted with methimazole—the hydrolysate of carbimazole—to form disulfide, which led to the decrease in the Raman intensity of the peak at 595 cm−1. The logarithm of the concentration of Cr6+ has a linear relationship with the Raman intensity at the characteristic peak and showed a limit of detection of 0.945 mg/kg for the tea sample. The carbimazole functionalized Au@AgNPs showed high selectivity in analyzing Cr6+ in tea samples, even in the presence of other metal ions. The SERS detection technique established in this study also showed comparable results with the standard ICP-MS method, indicating the applicability of the established technique in practical applications.

Au/SnS2 Hybrid Quantum Dots for Surface-Enhanced Raman Scattering-Based Monitoring and Photoreduction of Hg (II) Ions

“…Figures S8a,b show a linear relationship between the logarithm of Hg 2+ concentration and the equivalent SERS intensity of CV at 1620 cm –1 . The results were in the range of 92–106%, which is consistent with the allowable value of a quantitative study . All of these results mentioned above exhibit a great potential of Au/SnS 2 hybrid QDs for the SERS-based detection of Hg 2+ ions in practical use toward the real sample analysis.…”

“…The results were in the range of 92−106%, which is consistent with the allowable value of a quantitative study. 58 All of these results mentioned above exhibit a great potential of Au/SnS 2 hybrid QDs for the SERS-based detection of Hg 2+ ions in practical use toward the real sample analysis.…”

Do You Know What You Drink? Comparative Research on the Contents of Radioisotopes and Heavy Metals in Different Types of Tea from Various Parts of the World

“…On the other hand, Cr(VI) is toxic and carcinogenic to humans [58]. In addition, this microelement can be absorbed by plants from the contaminated soil or irrigation water [59]. The Cr content in black tea is much higher than that in other types of tea [60].…”