Application Of Ag(III)–luminol System And Quantum Dots In Chemiluminesecnce

Chemiluminescence(CL)-based analytical methods is one of the most sensitive methods. It was widely applied to pharmaceutical analysis,environment analysis,and clinical test.Quantum dots possess high photostability,tunable excitation and emission wavelength,good biocompatibility as well as excellent fluorescence properties. Therefore, they have become a hot subject. In this paper,carbon dots and graphene quantum dots were used in chemiluminescence. Several new methods of chemiluminescence were developed for the determination of pharmaceuticals. The major research works are as follows:1. A new chemiluminescince(CL) method for the determination of pesticide cyromazine is developed. The mechanism for enhancing effect of cetyl trimethyl ammonium bromide and inhibiting effect of cyromazine to the CL of Ag(III) complex–luminol in alkaline solution was proposed. The inhibition degree of CL emission was proportional to the logarithm of cyromazine concentration from 7.0×10–7 to 7.0×10–5 g/m L. The effects of the reaction conditions on CL emission and inhibition were examined. Under the optimized conditions, the detection limit(s/n=3) was 3.25×10–7 g/m L. The recoveries of cyromazine at three spiked levels(1.03, 7.0, and 10.5 mg/kg) were in the range of of 90.1–109% with the RSDs of 1.2–2.3%. The proposed method was used for the determination of cyromazine in spiked milk and milk powder samples with satisfactory results.2.Aqueous solutions of carbon dots(C-dots) were prepared by microwave-assisted thermal carbonization of poly(ethylene glycol). They were investigated by transmission electron microscopy,absorption and fluorescence spectra. It is shown that diperiodato-nicklate( Ⅳ), a strong oxidant, induces the chemiluminescence(CL) of C-dots in strongly alkaline solution without use of an additional reagent. A mechanism for this reaction is suggested.It is also found that the CL of the system is quenched by paracetamol, L-cysteine and glutathione. Under the conditions, the calibration plot is liner with a correlation coefficient(r) of>0.995. The limits of detection are 90,8,60μg/L for paracetamol,L-cysteine and glutathione, respectively.3. Aqueous solutions of carbon dots(CDs) were prepared by microwave-assisted thermal carbonization of poly(ethylene glycol). Graphene quantum dots(GQDs) were prepared by melting citric acid. They were investigated by transmission electron microscopy, absorption and fluorescence spectra. The CL intensity that potassium permanganate oxidize the mixture of CDs and GQDs is stronger than either one in acidic solution. Hydroquinone has inhibiting effect to the CL of KMn O4- CDs-GQDs system. Under the optimized conditions, the detection limit(s/n=3) was 8.46×10–8 g/m L. The CL intensity was proportional to the hydroquinone concentration in the range of 2.49×10–4-9.96×10–7g/m L. The recoveries of hydroquinone at three spiked levels were in the range of 89.45–101.3% with the RSDs of 0.9–2.1%.