Chemiluminescence Of Fluorescent Carbon Dots And Its Applications In The Environmental And Food Analysis

Carbon dots?CDs?,as a new class of fluorescent nanomaterials,have attracted considerable attention in recent years,because they have similar physico-chemical properties of heavy-metal containing quantum dots but relatively low in toxicity and cost of synthesis.Currently,CDs was applied in the fields of bioimaging,photocatalysis and sening.Chemiluminescence?CL?has high sensitivity,simple instrumentation,wide linear range and low background interference.The CL detection technique has widely incorporated CDs in many CL systems including luminol CL system,ultraweak CL system and oxidant induced CL system and broadens its application fields.In this work,the CDs were prepared taking glucose as carbon source.Aqueous solution of carbon dots?CDs?was prepared in a one-step ultrasonic approach and its absorption and fluorescence?FL?spectra were investigated.Three CDs-based CL systems were built based on flow injection chemiluminescence?FI-CL?method,the results are as follows:1.The acidic potassium per manganate could directly oxidize CDs to produce a chemiluminescence?CL?emission and the CL intensity was greatly enhanced in the presence of sulfide and iodide.The enhanced mechanism was suggested.After optimizing the reaction conditions,the enhanced CL intensity was linearly proportional to sulfide in the range from 1.0×10–6 mol/L to 1.0×10–4 mol/L with a detection limit of 2.0×10–7 mol/L and to iodide in the range of 3.0×10–6 mol/L to 1.0×10–4 mol/L with a detection limit of 3.5×10–7 mol/L.The relative standard deviation?RSD?was 1.7% and 2.1% for the deter mination of 1.0×10–5 mol/L sulfide or iodide?n=11?.The proposed method was employed to detect trace sulfide and iodide in the water and seaweed with recoveries of 95.0–102.5% and 95.5–99.5%.2.It was found that the mixing of CDs with luminol in the presence of potassium per manganate can induce a great sensitized effect on chemiluminescence?CL?emission.The strong sensitization effect of ?-naphthol on luminol-KMnO₄-CDs CL system was also obser ved.Based on the finding,a flow injection?FI?-CL method for ?-naphthol content detection in environmental water sample was developed.A mechanism for this CL system is suggested.The method described is simple,selective and obviates the need of extensive sample pretreatment.3.Sensitive detection of trace gallic acid?GC?in food samples has been accomplished via inhibition of luminol chemiluminescence?CL?by GC on the CDs-enhanced luminol-K₃Fe?CN?₆ CL system.Under the optimized experimental conditions,the CL intensity was found to be proportional to the concentration of GC ranging from 1.0×10–7 to 1.0×10–6 mol/L,1.0×10–6 to1.0×10–5 mol/L.The detection limit was estimated to be 1.5×10–8 mol/L.Via examining CL and UV-vis spectra of the CL system,possible mechanism in the CDs-enhanced CL assay and the follow-up inhibition of GC on the above system was proposed.