Nitrogen-doped fluorescence carbon dots as multi-mechanism detection for iodide and curcumin in biological and food samples

Iodine ion is one of the most indispensable anions in living organisms,particularly being an important substance for the synthesis of thyroid hormones.Curcumin is a yellow-orange polyphenol compound derived from the rhizome of Curcuma longa L.,which has been commonly used as a spice and natural coloring agent,food additives,cosmetics as well as Chinese medicine.However,excess curcumin may cause DNA inactivation,lead to a decrease in intracellular ATP levels,and trigger the tissue necrosis.Therefore,quantitative detection of iodine and curcumin is of great significance in the fields of food and life sciences.Herein,we develop nitrogen-doped fluorescent carbon dots(NCDs)as a multi-mechanism detection for iodide and curcumin in actual complex biological and food samples,which was prepared by a one-step solid-phase synthesis using tartaric acid and urea as precursors without adding any other reagents.An assembled NCDs-Hg^(2+) fluorescence-enhanced sensor for the quantitative detection of I^(-) was established based on a fluorescence“turn-off-on”mechanism in a linear range of 0.3-15μM with a detection limit of 69.4 nM and successfully quantified trace amounts of I^(-) in water samples and urine sample.Meanwhile,the as-synthesized NCDs also can be used as a fluorescent quenched sensor for curcumin detection based on the synergistic internal filtration effect(IFE)and static quenching,achieving a good linear range of 0.1-20μM with a satisfactory detection limit of 29.8 nM.These results indicate that carbon dots are potential sensing materials for iodine and curcumin detection for the good of our health.

Destruction of 4-phenolsulfonic acid in water by anodic contact glow discharge electrolysis

Destruction of 4-phenolsulfonic acid （4-PSA） in water was carded out using anodic contact glow discharge electrolysis. Accompanying the decay of 4-PSA, the amount of total organic carbon （TOC） in water correspondingly decreased, while the sulfonate group of 4- PSA was released as sulfate ion. Oxalate and formate were obtained as minor by-products. Additionally, phenol, 1,4-hydroquinone, hydroxyquinol and 1,4-benzoquinone were detected as primary intermediates in the initial stages of decomposition of 4-PSA. A reaction pathway involving successive attacks of hydroxyl and hydrogen radicals was assumed on the basis of the observed products and kinetics. It was revealed that the decay of both 4-PSA and TOC obeyed a first-order rate law. The effects of different Fe ions and initial concentrations of 4-PSA on the degradation rate were investigated. It was found that the presence of Fe ions could increase the degradation rate of 4-PSA, while initial concentrations lower than 80 mmol/L had no significant effect on kinetic behaviour. The disappearance rate of 4-PSA was significantly affected by pH.