The synthesis and application of L-cysteine graphene quantum dots for quantitative analysis of nitrite content in water

Abstract The limit standard of nitrite content in drinking water is an internationally recognized safety indicator. Some fluorescence analysis methods used for quantitative analysis of nitrite suffered from low anti-interference performance and inadequate specificity. In this article, L-cysteine graphene quantum dots have been synthesized and used to built a sensor system of ratiometric fluorescence with CdTe quantum dots. The L-cysteine graphene quantum dots were characterized by TEM and XPS. Results shown that the size of product is about 2 nm with homogeneous dispersion and a interplanar distance 0.235 nm, and there were hydroxyl, carboxyl, amino and sulfhydryl groups on its surface. Also, according to the linear association between nitrite concentrations and the ratio of fluorescence intensities at 421 and 570 nm (F421 nm/F570 nm), the quantitative analysis of nitrite in water has been realized, of which the linear range was 7.25 - 72.5 nmol/L, and the lowest detection limit was 3.012 nmol/L. This method with high sensitivity, selectivity, and anti-interference ability might be applied to analyze of nitrite in water quantitatively.