Polyethylenimine-Capped CdS Quantum Dots for Sensitive and Selective Detection of Nitrite in Vegetables and Water

Abstract

In the present work, polyethylenimine-capped CdS quantum dots (PEI-CdS QDs) with bright green fluorescence were synthesized and applied for sensitively and selectively detecting the nitrite in vegetable and water samples. Highly fluorescent and environment-friendly PEI-CdS QDs (quantum yield about 8%) with diameters of ca. 5 nm were easily synthesized by using hyperbranched PEI as functional polymer. Formation of the PEI-CdS QDs was verified by transmission electron microscopy and UV-vis spectroscopy. The fluorescence intensity of the as-synthesized PEI-CdS QDs was enhanced pronouncedly by the increasing amount of PEI and was stable when the pH ranged from 5.0 to 9.0. Our results demonstrated that the fluorescence of the PEI-CdS QDs was effectively quenched by the nitrite in a rather wide linear range of 1.0 × 10-1.0 × 10 M while efficiently avoiding the interferences from nitrate ions and other commonly coexisting anions of nitrite in the vegetable samples. The detection limit of the present method was lower than the maximum limit of nitrite in drinking water (6.5 × 10 M) ruled by the World Health Organization, which is significant to the application of the method.

The synthesis of a chemically reactive and polymeric luminescent gel

“…, blue baby syndrome or methemoglobinaemia). 53–58 The World Health Organization (WHO) has set the maximum limit for NO 2 − in drinking water as 65 μM. 53,59,60 Thus, it is of utmost importance to develop a portable sensor for the facile and unambiguous detection of the nitrite level in drinking water even in remote places, where the availibility of sophisticated instrumentation is limited.…”

Au nanoparticle-loaded eggshell for electrochemical detection of nitrite

“…4,5 In addition, nitrite is a widely used preservative because it can effectively inhibit the reproduction of microorganisms. [6][7][8] Oolong tea, as a Chinese specialty drink, is well-known worldwide for its unique avor and rich nutritional value. However, it is susceptible to nitrite contamination during production and processing.…”

Ratiometric Colorimetric Detection of Nitrite Realized by Stringing Nanozyme Catalysis and Diazotization Together

“…Until today, a few approaches based on different principles have been explored and applied for nitrite analysis [1], including chromatography [5][6][7], electrochemistry [8][9][10][11][12][13], fluorometry [14][15][16][17][18][19], and colorimetry [20][21][22][23][24][25][26][27][28][29][30][31][32]. Among these methodologies, colorimetric assays attract special interest because of their superiorities of convenient signal reading, result visualization, and simple operation.…”