Rapid Determination of Six Pesticides in Water Samples Using Ultrasound-assisted Dispersive Liquid-Liquid Microextraction Coupled with High Performance Liquid Chromatography / 分析化学

A novel method for accurate,fast and sensitive detection of pesticides such as imidacloprid,isocarbophos,phoxim,dursban,imidacloprid,pyridaben and avermectin in environmental water samples has been developed by using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with high performance liquid chromatography with ultraviolet detection (HPLC-UV).The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents,ultrasonic time,ionic strength and extraction time were investigated.Under the optimized extraction conditions,the linearity for the detection of six pesticides in the concentration range of 10-600 μg/L was obtained with limits of detections (LODs) of 0.8-3.1 μg/L and relative standard deviations (RSDs) of 4.7％-11.3％.UA-DLLME method exhibited strong enrichment ability for the six pesticides,and the enrichment factor (EFs) were ranged from 58 to 187.This method had perfect linearity,precision and recovery results,and showed obvious advantages and practicality comparing the previously reported methods.

Study of Electrochemical Sensor for Nitrite Based on Composites of Zirconium Dioxide Nanoparticles/Reduced Graphene Oxide / 分析化学

A nitrite electrochemical sensor based on electrodeposition of zirconium dioxide nanoparticles on reduced graphene oxide modified electrode was successfully constructed for the detection of nitrite. The electrochemical behavior of the modified electrode was investigated by cyclic voltammetry and amperometric i-t curve. Under the optimal conditions, the amperometric i-t curve response of the electrode showed a linear relationship with nitrite concentration in the range of 3.0×10Symbolm_7-1.0×10Symbolm_6 mol/L and 1.0×10Symbolm_6-6.0×10Symbolm_6 mol/L, and the detection limit was 1.0×10Symbolm_7 mol/L (S/N=3). The fabricated sensor exhibited high sensitivity, good stability and high reproducibility. This sensor was applied for the detection of nitrite in sausage samples with favorable recoveries of 93.7％-110.4％ and relative standard deviation (RSD) of 1.6％-2.1％.

Highly Sensitive Detection of Spermine Based on Fluorescence Quenching of Gold Nanoclusters / 分析化学

A new type of fluorescent gold nanoclusters (MU-Au NCs) was prepared by hydrothermal synthesis method using ammonium benzoate murexide (MU) as reducing agent and protecting agent.The synthesis method was simple and rapid.Based on the fluorescence quenching ability of spermine, a turn off type fluorescence analysis method was established for rapid and ultra sensitive detection of spermine.The linear range for detection of spermine was 0.003-300 μmol/L and the detection limit was 1 nmol/L (S/N=3).The established analytical method of spermine provided theoretical basis and reference for construction of spermine biosensor and actual sample detection.

A Hydrogen Peroxide Sensor Based on Palladium Nanoparticles Loading to Poly(amidoamine) Dendrimers Functionalized Carbon Nanotubes / 分析化学

The fourth generation poly( amidoamine) dendrimers ( G4. 0 PAMAM) functionalized multiwalled carbon nanotube ( G4 . 0-MWCNTs ) was prepared by amidation between carboxylated multiwalled carbon nanotube (MWCNTs) and G4. 0 PAMAM. Then a novel hydrogen peroxide (H2O2) sensor was fabricated by electrodepositing Pd nanoparticles (NPs) on a glassy carbon electrode (GCE) modified with G4. 0-MWCNTs composites. The modified electrode was characterized by field emission scanning electron microscopy ( FESEM) , cyclic voltammetry ( CV) and electrochemical impedance spectroscopy ( EIS) . A large amounts of highly dispersion PdNPs could be well loaded on the surface of the G4. 0-MWCNTs, and the modified electrode exhibited excellent electrocatalytic activity towards the reduction of H2 O2 . Under the optimized conditions, the reduction peak currents of H2 O2 were linear to their concentrations in the range from 1. 0 × 10-9 mol/L to 1. 0×10-3 mol/L and the limit of detection of 2. 3×10-8 mol/L was obtained. The recovery of standard addition for human serum samples was 96 . 7%-103 . 1%.

A Hydrogen Peroxide Sensor Based on Pt@Au Nanoparticles Loading to Polyethyleneimine Functionalized Carbon Nanotubes / 分析化学

A novel hydrogen peroxide sensor was fabricated by the seed-mediated growth method. First, polyethyleneimine(PEI) functionalized multiwalled carbon nanotubes(MWNTs) were used as growth scaffold on the glass carbon electrode ( GCE). Then, Au nanoparticles were electrodeposited uniformly as seeds. Finally, Pt nanoparticles ( PtNPs ) grew on Au nanoparticles to form Pt @ Au core-shell structure nanocomposite. A new type of electrochemical sensor based on Pt @ Au / PEI-MWNTs nanocomposites for detection of hydrogen peroxide was developed, and the designed Pt@ Au / PEI-MWNTs/ GCE was characterized by electrochemical methods and field emission scanning electron microscopy (FESEM). The Differential pulse experimental results showed that the modified electrode exhibited excellent electrocatalytic activity towards the reduction of H2 O2 with the wide linear range from 9. 2 ×10-8 mol/ L to 1. 3 ×10-3 mol/ L. The correlation coefficient was 0. 9994 and the low detection limit was 3. 1×10-8 mol/ L at the signal-to-noise of 3.