Detection of Rutin in Sophorae Immaturus Flos with Electrochemical Sensor Assembled with Gold Nanoparticles/Nafion/Multi-wall Carbon Nanotube / 中国实验方剂学杂志

Objective::A new-type electrochemical sensor was developed by electrodepositing gold nanoparticle on the surface of glassy carbon electrode (GCE) modified by Nafion-multi-wall carbon nanotube (MWNTs) by the potentiostatic method, and used for the detection of rutin in practical samples. Method::The electrochemical properties of the sensor in potassium ferricyanide-potassium ferrocyanide system were studied by electrochemical impedance spectroscopy and cyclic voltammetric method, in order to explore the electrochemical performance of the sensor. The electrochemical behavior of rutin on the surface of the sensor was studied by the cyclic voltammetric method, and the factors affecting the performance of the sensor were optimized. The content of rutin was determined by differential pulse voltammetric methods. Result::The optimized conditions were -0.25 V of the deposition potential of gold nanoparticle, 20 s of the deposition time, pH 3.0, and 6 μL of 1 g·L-1 carbon nanotube. Under the conditions, a good linear relationship between reduction peak current and rutin concentration was obtained from 5.0 ×10-9 to 7.0 ×10-7 mol·L-1, and the detection limit was 3.6×10-9 mol·L-1. Conclusion::The developed sensor has a good electrical conductivity and stability, and is highly sensitive and simple for the detection of rutin, with a low detection limit. It has been successfully applied to the detection of rutin in Sophorae Immaturus Flos with the recoveries between 97.6%and 104.4%, which provides a new method for the determination of rutin and a new idea for the quality control of Chinese medicinal materials.

Electrochemical Analysis of Azodicarbonamide in Hot Solution by Using Nation Film Electrode / 分析化学

Based on the high solubility of azodicarbonamide (ADC) in hot solution and its electrostatic interaction with Nafion film,a new electroanalytical method was developed for the determination of ADC by using Nafion film electrode.The effect of temperature on the solubility of ADC and the mechanism of the reduction reaction of ADC on Nafion film electrode were investigated.Under the experimental conditions such as water bath at a constant temperature of 80 ℃,pH 6.0 and optimal test parameters,the differential pulse voltammetric response was proportional to the concentration of ADC in the range of 0.93-10.5 μg/L,and the detection limit was estimated to 0.58 μg/L.The relative standard deviation was less than 5.86 ％ and the recovery was 95.8％-104.0％ for the determination of the ADC in flour samples.The semicarbazide and nitrofurazone did not interfere with the determination of ADC.

A Novel Dopamine Sensor Based on Single-Walled Carbon Nanotubes/Nafion/Copper Nanoparticles Nanocomposites / 分析化学

An economic and facilely prepared dopamine ( DA) sensor have been successfully fabricated by the electrodeposition of copper on single-walled carbon nanotubes ( SWNTs )/Nafion-modified glassy carbon electrode. The morphology of the material was observed by scanning electron microscopy ( SEM) and element composition of the material was investigated by energy dispersive X-ray spectroscopy ( EDX ) . Tests with various scan rates and pH conditions indicated that an adsorption-controlled process occured in the electrochemical system. The mechanism of the electrode reaction of dopamine involved a two-electron process which was accompanied by a deprotonation step. Electrochemical parameters were calculated with the electron transfer number as 2 . 67 , the charge transfer coefficients as 0 . 6 , the apparent heterogeneous electron transfer rate constant as 1. 38 s-1 . Under the optimal conditions with differential pulse voltammetric measurement, the linear equation was Ipa(μA)=-0. 054c (μmol/L)-3. 82(R2=0. 9988), with linear range of 5-100 μmol/L and detection limit of 0 . 0135 μmol/L ( S/N=3 ) . The main advantages of sensor included facile fabrication approach, high sensitivity, good stability and high reproducibility. The sensor was applied to the detection of DA in volunteer urine by differential pulse voltammetry with favorable recoveries of 96 . 5%-100 . 4% and relative standard deviations (RSDs) of 1. 2%-2. 4%.

A simple and sensitive method for determination of Norfloxacin in pharmaceutical preparations / Um método simples e sensível para determinação da norfloxacina em preparações farmacêuticas

In this approach, a new voltammetric method for determination of norfloxacin was proposed with high sensitivity and wider detection linear range. The used voltammetric sensor was fabricated simply by coating a layer of graphene oxide (GO) and Nafion composited film on glassy carbon electrode. The advantage of proposed method was sensitive electrochemical response for norfloxacin, which was attributed to the excellent electrical conductivity of GO and the accumulating function of Nafion under optimum experimental conditions, the present method revealed a good linear response for determination of norfloxacin in the range of 1×10^-8mol/L-7×10^-6 mol/L with a detection limit of 5×10^-9 mol/L. The proposed method was successfully applied in the determination of norfloxacin in capsules with satisfactory results...

Propos-se, por essa abordagem, novo método voltamétrico, com alta sensibilidade e faixa linear de detecção mais ampla, para a determinação de norfloxacino. O sensor voltamétrico utilizado foi fabricado simplismente por cobertura de camada de óxido de grafeno (GO) e filme de Nafion em eletrodo de cabrono vítreo. A vantagem do método proposto foi a resposta eletroquímica sensível para o norfloxacino, atribuída à condutividade elétrica excelente do GO e à função acumulada do Nafion. Sob condições experimentais ótimas, o presente método revelou boa resposta linear para a determinação do norfloxacino na faixa de limite de detecção de 1×10^-8mol/L-7×10^-6 mol/L. O método proposto foi aplicado com sucesso na determinação de norfloxacino em cápsulas, com resultados satisfatórios...

Electrocatalytic oxidation and determination of dopamine at a carbon ionic liquid electrode modified with nafion-L-aspartic acid composite film / 药物分析学报

The electrocatalytic oxidation of dopamine (DA) was studied by electrochemical approaches at a carbon ionic liquid electrode (CILE) modified with the composite film of nafion and L-aspartic acid (NL-CILE). The CILE was fabricated by replacing non-conductive organic binders with a room-temperature hydrophobic ionic liquid, 1-butyl-3-methyl-imidazolium hexafluorophosphate. The composite film of NL was used as matrix to adsorb DA and catalyze the oxidation of DA in phosphate buffer solution (PBS). The electrochemical response of DA was investigated at the NL-CILE, the traditional carbon paste electrode (TCPE), CILE and the nafion modified CILE (N-CILE) in 0.1M PBS (pH 7.4), respectively. The results showed the superiority of NL-CILE to N-CILE, CILE and TCPE in terms of provision of higher sensitivity, faster electron transfer and better reversibility. Under optimum condition, the oxidation peak current was rectilinear with DA concentration range from 0.1μM to 0.1mM, with a detection limit of 0.03μM (S/N=3) by differential pulse voltammetry. The proposed method was applied to determine DA in samples successfully.

Electrocatalytic oxidation and determination of dopamine at a carbon ionic liquid electrode modified with nafion-L-aspartic acid composite film / 西安交通大学学报·英文版

The electrocatalytic oxidation of dopamine (DA) was studied by electrochemical approaches at a carbon ionic liquid electrode (CILE) modified with the composite film of nafion and L-aspartic acid (NL-CILE). The CILE was fabricated by replacing non-conductive organic binders with a room-temperature hydrophobic ionic liquid, 1-butyl-3-methyl-imidazolium hexafluorophosphate. The composite film of NL was used as matrix to adsorb DA and catalyze the oxidation of DA in phosphate buffer solution (PBS). The electrochemical response of DA was investigated at the NL-CILE, the traditional carbon paste electrode (TCPE), CILE and the nafion modified CILE (N-CILE) in 0.1 M PBS (pH 7.4), respectively. The results showed the superiority of NL-CILE to N-CILE, CILE and TCPE in terms of provision of higher sensitivity, faster electron transfer and better reversibility. Under optimum condition, the oxidation peak current was rectilinear with DA concentration range from 0.1 μM to 0.1 mM, with a detection limit of 0.03 μM (S/N=3) by differential pulse voltammetry. The proposed method was applied to determine DA in samples successfully.

Determination of Dopamine on Poly(amino black 10B)/Nafion Modified Electrode / 分析化学

A poly(amino black 10B)/Nafion modified glassy carbon(GC) electrode for the detection of dopamine(DA) has been developed. The modified electrode showed an excellent electrocatalytic effect on the oxidation of DA. In cyclic votammetric measurements, the redox peak current increased linearly with the concentration of DA in the range of 2.0×10~(-7) 3.0×10~(-5) mol/L in PBS of pH 6.0, with a correlation coefficient of 0.9993 and 0.9991, respectively. The detection limit(S/N=3) was 1.0×10~(-7) mol/L. Moreover, the modified electrode exhibited good repeatability and long-time stability, and avoided the interference of ascorbic acid. The modified electrode has been used for the determination of DA in the injections and calf serum with good recovery and reproducibility.