芦丁在纳米金修饰玻碳电极上的电化学行为及其测定

采用循环伏安法将纳米金电沉积于玻碳电极表面,制备了纳米金修饰玻碳电极(NG/GCE).在pH3.29的Britton-Robinson(B-R)缓冲溶液中,用循环伏安法研究了芦丁在NG/GCE上的电化学行为.结果表明,NG/GCE对芦丁的氧化还原反应有良好的电催化作用.用方波伏安法测得芦丁的还原峰电流与其浓度在2.0×10-8～2.0×10-6mol/L范围内呈线性关系,检出限为1.0×10-8mol/L(S/N=3).     

葡萄糖在纳米金修饰金电极上电化学行为研究

利用电还原氯金酸制备了纳米金(Nano-gold,NG)修饰Au电极。该电极对葡萄糖有催化作用,可能是由于纳米金降低了OH-表面吸附能,增加了OH-在电极表面的吸附量。通过循环伏安法研究了扫描速度、温度、本体浓度和溶液pH值对葡萄糖氧化的影响。     

咖啡酸在多壁碳纳米管修饰玻碳电极上的电化学行为及其测定

制备了多壁碳纳米管(MWNT)修饰玻碳电极,并研究了咖啡酸在该电极上的电化学行为及其测定方法,与裸玻碳电极(GCE)相比,MWNT膜修饰电极(MWNT/GCE)能显著提高咖啡酸的氧化峰电流.在pH=3.29的B-R缓冲溶液中,咖啡酸在MWNT/GCE电极上出现1对准可逆的氧化还原峰,Epa=0.47 V,Epc=0.32 V,峰电流与其浓度在5.0×10-7～2.0×10-5 mol/L范围内成线性关系,检出限为5.0×10-7mol/L.实际样品测定的相对标准偏差(RSD)为0.82％(n=5),平均回收率为100.7％.MWNT膜对咖啡酸的电化学氧化有明显的催化作用.该法是一种快捷、可靠、灵敏的检测方法,可以用于咖啡酸含量的测定.     

间苯二酚在金纳米粒子/碳纳米管修饰电极上的电化学行为

制备了金纳米粒子/碳纳米管复合修饰玻碳电极,并用于研究间苯二酚的电化学反应过程,结果发现金纳米粒子与碳纳米管均对间苯二酚的电化学反应具有催化作用,复合修饰电极很好地利用了两种纳米粒子的电催化活性,对间苯二酚具有更强的电化学催化效果,为应用电化学技术进行间苯二酚的检测提供了可能。同时研究了碳纳米管的用量、复合膜的层数、pH值、介质和扫速等条件对间苯二酚的电化学信号的影响情况。     

双酚A在壳聚糖-FC-134-碳纳米管修饰电极上的电化学行为及其测定

采用十二烷基硫酸钠(SDS)与全氟辛基磺酰季碘化物FC-134作为碳纳米管的复合分散剂,制备了壳聚糖-碳纳米管修饰电极(MFC/GCE)。研究了环境激素双酚A在pH 8.0磷酸盐缓冲溶液中的电化学行为,并探讨了其电极过程机理。峰电位为0.450 V,峰电流与其浓度在2.5×10-7~1.0×10-4mol/L范围内呈线性关系,检出限为1.0×10-8mol/L。该法用于环境水样中双酚A含量的测定并与荧光法对照,测定结果吻合。     

碳纳米管/纳米金修饰金电极上柔红霉素电化学行为的研究

将碳纳米管与纳米金结合修饰在金电极上制成修饰电极,并用于柔红霉素(DNR)的电化学行为研究和检测.在4.4 mmol/L磷酸盐缓冲溶液(pH=5.81)中,DNR在碳纳米管-纳米金/Au电极上有一对灵敏的氧化还原峰.还原峰电流与DNR的浓度在3.2×10-8～1.0×10-6mol/L和1.0× 10-6～2.2× 1...     

吲哚美辛在单壁碳纳米管修饰电极上的电化学行为

运用伏安法研究了吲哚美辛在单壁碳纳米管修饰电极上的电化学行为.在0.1 mol/L HAc-NaAc缓冲溶液(pH 4.5)中,吲哚美辛于0.91 V (vs.SCE)电位处有一个峰形很好的氧化峰.与裸玻碳电极相比,吲哚美辛在修饰电极上的电位正移了约30 mV,峰电流增加了近10倍,表明该修饰电极对吲哚美辛有较强的电催化作用.搅拌条件下开路富集2 min,氧化峰电流与吲哚美辛在5.5×10-7～1.1×10-5 mol/L浓度范围内呈良好的线性关系,检出限为1.1×10-7 mol/L.该方法可用于药剂中吲哚美辛的分析.     

纳米金–壳聚糖修饰电极循环伏安法测定抗坏血酸

介绍纳米金–壳聚糖修饰电极的制备方法及其测定抗坏血酸的分析应用。采用电沉积方法,将氯金酸与壳聚糖的混合电解液直接共沉积,制备了壳聚糖–纳米金修饰玻碳电极的电化学传感器。利用循环伏安法研究了抗坏血酸浓度、p H值等对抗坏血酸在修饰电极上的电化学行为的影响。实验结果表明,修饰电极对抗坏血酸具有良好的电催化氧化作用,抗坏血酸浓度在5×10~(–5)~1×10~(–3) mol/L范围内线性良好,回归方程为I_p=0.433 8c+0.881 9,相关系数为0.998 71。该法可指导纳米金–壳聚糖修饰电极的制备及抗坏血酸含量的测定。     

芦丁在铂纳米/碳纳米管修饰电极上电化学行为研究

通过电沉积的方式在多壁碳纳米管(MWCNTs)修饰玻碳电极表面上沉积铂(pt)纳米粒子,并运用循环伏安法(CV)、示差脉冲伏安法(DPV)探讨了芦丁在铂纳米/碳纳米管/玻碳电极上的电化学行为.实验结果表明,芦丁在该修饰电极上呈现一对良好氧化还原峰,其氧化峰电流与浓度在3.2×10(-8)～1.2×10(-5)mol/L...     

维生素b12在多壁碳纳米管修饰玻碳电极上的电化学行为及其分析测定

维生素b12;多壁碳纳米管;循环伏安法;修饰电极     

Portable Electrochemical Sensing of Indole-3-acetic Acid Based on Self-assembled MXene and Multi-walled Carbon Nanotubes Composite Modified Screen-printed Electrode

As a typical plant hormone, indole-3-acetic acid (IAA) can regulate the biological activities including division, growth and differentiation of plant cells. In this paper, a MXene and multi-walled carbon nanotubes composite was prepared by self-assembly procedure, which was modified on screen-printed electrode (SPE) to construct a wireless portable electrochemical sensor. Electrochemical investigations of IAA were studied by cyclic voltammetry and an irreversible oxidation process could be observed. The excellent electroanalytical method of IAA was realized on the modified SPE with the detection range as 0.05–125.0 μmol/L and the detection limit as 16.7 nmol/L. The sensor was used for IAA content analysis in different part of pea seedlings with satisfactory results.     

Simultaneous Electrochemical Determination of Indole-3-acetic Acid and Salicylic Acid in Pea Roots using a Multiwalled Carbon Nanotube Modified Electrode

Indole-3-acetic acid and salicylic acid are essential phytohormones with profound effects on growth and development as well as stress responses of plants. Accumulating evidence has suggested that these compounds mediate the same biological process by collaboration or antagonistic actions. Simultaneous determination of indole-3-acetic acid and salicylic acid may significantly improve the understanding on mechanisms of their interaction. In this study, the simultaneous determination of these analytes was electrochemically performed using a multiwalled carbon nanotubes-chitosan modified glassy carbon electrode. Based on differential pulse voltammetry, indole-3-acetic acid and salicylic acid were determined from 0.67 to 48.82 micromolar with detection limits of 0.1 micromolar. In addition, no interferences were observed from other molecules. This method was employed for the simultaneous determination of the analytes in pea root extracts. The approach may be extended for additional study of the interaction of indole-3-acetic acid and salicylic acid in plants.     

吲哚-3-乙酸分子印迹聚合物膜电化学传感器的研制

利用分子印迹技术,以吲哚-3-乙酸(IAA)为模板分子,甲基丙烯酸为单体,在玻碳电极表面采用原位聚合制备分子印迹敏感膜.采用方波伏安法对吲哚乙酸在该印迹电极上的电化学行为进行了研究.结果表明,0.62 V(vs.SCE)处的峰电流与吲哚乙酸的浓度在5.0×10-6～2.0×10-4mol/L范围内呈线性关系,检出限(S...     

Amperometric Determination of Indole-3-acetic Acid Based on Platinum Nanowires and Carbon Nanotubes

Over the past few years, extensive research has been focused on the preparation, purification, and possible application of the CNT1-3. The unique electronic, chemical, and mechanical properties of CNT make it extremely attractive for electrochemical sensi…     

Determination of Indole-3-acetic Acid and Abscisic Acid by Double-Direction Dispersive Liquid–Liquid Microextraction Coupled with High-Performance Liquid Chromatography

A method for the separation and purification of indole-3-acetic acid and abscisic acid based on double-direction dispersive liquid–liquid microextraction coupled with high-performance liquid chromatography was developed. The reverse-direction dispersive liquid–liquid microextraction procedure was very efficient in the purification of the hormones. The forward-direction dispersive liquid–liquid microextraction procedure was very efficient in the enrichment of the analytes. Under optimum conditions, a linear response was observed over the ranges of 0.2 µg/g to 200.0 µg/g for indole-3-acetic acid and 0.1 µg/g to 200.0 µg/g for abscisic acid, with correlation coefficients of 0.9967 and 0.9983. The limits of detection for indole-3-acetic acid and abscisic acid were 0.02 µg/g and 0.01 µg/g. The recoveries by standard addition were 91.4% and 88.6% for indole-3-acetic acid and abscisic acid with corresponding relative standard deviations of 4.5% and 6.1% (n = 5). The developed method was used for the preconcentration and determination of indole-3-acetic acid and abscisic acid in Arabidopsis thaliana, and satisfactory results were obtained.     

A Novel Electrochemical Sensor Based on Modified Carbon Paste Electrode with ZnO Nanorods for the Voltammetric Determination of Indole-3-acetic Acid in Plant Seed Extracts

Detection of indole-3-acetic acid (IAA), as a phytohormone, is important for precision farming, plant phenotyping, and crop management. Herein, IAA was detected in bean and wheat plant seeds extractions using zinc oxide nanorods/carbon paste electrode (ZnO NRs/CPE). ZnO NRs/CPE showed excellent electrocatalytic activity, high sensitivity, and selectivity toward the oxidation of IAA. The linearity range was from 30.×10⁻⁸ to 5.0×10⁻⁶ M (r²=0.996, n=10), with a detection limit of 1.7×10⁻⁸ M. Moreover, ZnO NRs/CPE exhibited high reproducibility, with a standard deviation of 1.0 % for six successive measurements of IAA.     

Improved Procedure for Determining Free and Conjugated Indole-3-Acetic Acid by a Spectrofluorimetric Kinetic Method

Abstract

The Indole-3-acetic acid (IAA), ester-and amide-linked IAA in peach seeds were determined by a kinetic method based on the measurement of the Indole-α-pyrone derivative of the free acid. The free acid concentration was 355 ng/g of fresh weight, the concentrations for the ester-and amide-conjugated IAA were 877 and 1785 ng/g of fresh weight, respectively. The relative standard deviation was always less than 15%.     

氟嗪酸在碳纳米管修饰电极上的电化学行为及含量的测定

在玻碳电极上制备了多壁碳纳米管/Nafion(MWNTs-Nafion)膜,用交流阻抗谱(EIS)、循环伏安法(CV)、线性扫描伏安法(LSV)研究了氟嗪酸在该膜上的电化学行为。与裸玻碳电极相比,这种纳米结构膜修饰的电极对氟嗪酸的电化学氧化显现出极好的促进作用,氟嗪酸的氧化峰电流明显增强,在修饰电极上于 0.97 V处产生了1个灵敏氧化峰。LSV测定氟嗪酸的线性范围为1.0×10-8～1.0×10-6mol/L和1.0×10-6～2.0×10-5mol/L,开路富集400 s后,检出限为8.0×10-9mol/L(3倍信噪比),方法可用于人尿中氟嗪酸的实时测定。     

A Polypyrrole‐Imprinted Electrochemical Sensor Based on Nano‐SnO2/Multiwalled Carbon Nanotubes Film Modified Carbon Electrode for the Determination of Oleanolic Acid

A sensitive molecularly imprinted electrochemical sensor with specific recognition ability for oleanolic acid was synthesized by modification of multiwalled carbon nanotubes (MWNTs) decorated with tin oxide nanoparticles (nano‐SnO₂/MWNTs) and polypyrrole‐imprinted polymer on a carbon electrode. The morphology and electrochemical performance of the imprinted sensor were investigated by using scanning electron microscope (SEM), X‐ray diffraction (XRD), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometric i–t curve. The results showed that the imprinted sensor displayed excellent selectivity toward oleanolic acid. A linear relationship between the response currents and oleanolic acid concentrations ranging from 5.0×10^?8 g/L to 2.0×10^?5 g/L was obtained for the imprinted sensor. The limit of detection (LOD) of the imprinted sensor toward oleanolic acid was calculated as 8.6×10^?9 g/L at a signal to noise ratio (S/N) of 3. This imprinted sensor was successfully applied to the determination of oleanolic acid in Acitinidia deliciosa root samples.     

Amperometric Determination of lndole-3-acetic Acid Based on Platinum Nanowires and Carbon Nanotubes

Platinum nanowire （PtNW） can be grown by electrodeposition in polycarbonate membrane, with the average diameter of the nanowires about 250 nm. The PtNW and multiwalled carbon nanotubes （CNT） are then dispersed into chitosan （CHIT） solution. The resulting PtNW-CNT-CHIT material brings new capabilities for electrochemical devices by using the synergistic action of the electrocatalytic activity of PtNW and CNT. By dropping the PtNW-CNT-CHIT film onto the glassy carbon （GO） electrode surface, and after evaporation an amperometric sensor for the determination of indole-3-acetic acid （IAA） was developed. The oxidation current of IAA increased significantly at the PtNW-CNT-CHIT film coated GC electrode, in contrast to that at the CNT-CHIT modified GC. The linear response of the sensor is from 50 ng/ml to 50 μg/ml with a detection limit of 25 ng/mL.