Chemiluminescence Of Nitrogen Doped Fluorescent Carbon Quantum Dots And Its Applications

Chemiluminescence?CL?method has become one of the most potential analytical methods owing to no need of light source,high sensitivity,wide linear range,simple instrumentation.In recent years,CL has been extended from the traditional molecular system to nanometer system with the development of nanotechnology to improve the sensitivity and expand the application range of CL.Nitrogen doped fluorescent carbon quantum dots?NFCDs?,as a metal-free nanomaterial consists of carbon and nitrogen,have the advantage of bright fluorescence,good dispersibility and stability,and nontoxicity.Up to now,NFCDs have been widely used as fluorescent probes for biological and environment detection.Therefore,exploring new CL systems that NFCDs are involved is of great theoretical significance and application value.In this work,the NFCDs were synthesized using ascorbic acids and aqueous ammonia as precursors through a facile one-pot ultrasonic method and then its effect on the novel CL system was explored.Three NFCDs-based FI-CL analysis methods were built.The main content is as follows:1.In the acidic mediums,potassium permanganate?KMnO₄?or Ce?IV?could directly oxidize NFCDs to produce relatively intense CL.The CL intensity of the KMnO₄-NFCDs system was obviously increased in the presence of thiourea?TU?or tannic acid?TA?,and whether TU or TA had no effect on the CL intensity of Ce?IV?-NFCDs system.Thus,a method based on KMnO₄-NFCDs system for the determination of TU/TA was established.Under the optimum conditions,the linear range was 1.0×10–7 to 1.0×10–5 mol/L with a detection limit of 3.8×10–8 mol/L for TU,and 7.0×10–8 to 7.0×10–6 mol/L with a detection limit of 2.6×10–8 mol/L for TA.The method had been applied to the determination of trace TU in the orange juice and orange peel,and TA in the Chinese gall with satisfactory result.2.The ultraweak CL reaction of Na₂SO₃ with Ce?IV?was greatly amplified by NFCDs.Interestingly,3-indolyl acetic acid?IAA?dramatically suppressed the CL of Ce?IV?-Na₂SO₃-NFCDs system.Based on this,a new CL method had been designed for the analysis of trace levels of IAA in real water samples.The relative CL intensity was proportional to the concentration of IAA in the range from 2.0×10-8 to 1.0×10-6 mol/L.The detection limit was 5.6×10-9 mol/L.3.In alkaline condition,NFCDs could significantly sensitize the CL reaction of KMnO₄-luminol.The addition of trace amount of Mn?II?ion into the CL system caused significant quenching luminescence intensity.Under the optimum conditions,the inhibited CL intensity was proportional to the concentration of Mn?II?ion in the ranges of 3.0×10-7 to 5.0×10-5 mol/L.The detection limit was 4.3×10-8 mol/L.The method was successfully applied to the determination of Mn?II?ion concentrations in water samples.