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1.
Nicotinamide (NA) yields a polarographic catalytic wave with a peak potential –1.38 V (vs. SCE) in 0.1 mol/L HAc-NaAc (pH
4.7)/4 × 10–3 mol/L KIO3 buffer solution. The sensitivity of the catalytic wave increased in one order of magnitude as compared to that of the responding
reduction wave without KIO3. Based on this observation, a new method for the determination of NA was recommended. The second order derivative peak current
was proportional to the NA concentration in the range of 5 × 10–8 – 6 × 10–7 mol/L. 0.11-fold vitamin B1, 0.13-fold B2, 0.14-fold B6 and 8-fold nicotinic acid amounts do not interfere the determination of 1 × 10–6 mol/L NA. The proposed method was used to determine the NA content in multivitamin tablets, with good agreement to the declared
amount.
Received: 25 October 1999 / Revised: 28 March 2000 / /Accepted: 31 March 2000 相似文献
2.
In a 0.125 mol/L phosphate (pH 6.6)/2.5 x 10(-4) mol/L 2-iodoacetamide solution, lomefloxacin yields a response of a polarographic catalytic current. The second-order derivative peak current of the catalytic wave of lomefloxacin is proportional to its concentration in the range of 1.0 x 10(-8)-1.0 x 10(-6) mol/L (r = 0.998). The sensitivity of the catalytic wave is 25-times higher than that of the corresponding reduction wave for 5.0 x 10(-7) mol/L lomefloxacin. The proposed method was applied to the determination of lomefloxacin in pharmaceutical preparations. The polarographic reduction wave is ascribed to a one-electron reduction of the C=C bond of lomefloxacin zwitterion accompanied by an acid-base equilibrium. The catalytic wave should be caused by regeneration of the lomefloxacin molecule at electrode surface due to the one-electron reduction product being further oxidized by electroreductive intermediate products of 2-iodoacetamide. 相似文献
3.
极谱催化波法测定苯甲醛 总被引:11,自引:0,他引:11
在磷酸盐缓冲溶液中 ,苯甲醛与联氨反应生成的产物苯甲醛腙在K2 S2 O8存在时于 - 1.2 2V(vs.SCE)产生一灵敏的极谱催化波。基于此 ,拟定了测定痕量苯甲醛的新方法。在 8.0× 10 -2 mol/LKH2 PO4 NaOH(pH 8.0± 0 .2 ) 2 .5× 10 -2 mol/L联氨 - 3.5× 10 -2 mol/LK2 S2 O8底液中 ,极谱催化波峰电流与苯甲醛浓度在 1.0× 10 -9~ 6 .2× 10 -8mol/L范围内呈线性关系 ,比无K2 S2 O8存在时灵敏度提高约 6 0倍。本方法适用于生活污水中苯甲醛含量的测定 相似文献
4.
5.
beta-Alanine was covalently grafted on a glassy carbon electrode (GCE) by amine cation radical formation in the electrooxidation process of the amino-containing compound. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) proved the immobilization of beta-alanine monolayer on GCE. The electrode shows strong electrocatalytic functions to dopamine (DA) and ascorbic acid (AA), reducing the overpotentials by 0.20 V and 0.23 V, respectively. Due to its different catalytic effects toward DA and AA, the modified electrode resolved the overlapping voltammetric responses of DA and AA into two well-defined voltammetric peaks by CV or differential pulse voltammetry (DPV), which can be used for the simultaneous determination of these species in a mixture. The catalytic peak current obtained from DPV was linearly related to DA and AA concentrations in the ranges of 4.0 x 10(-6)-5.0 x 10(-4) mol/L and 2.0 x 10(-5)-6.0 x 10(-3) mol/L with correlation coefficients of 0.997 and 0.995, respectively. The detection limits (3 sigma) for DA and AA were 2.4 x 10(-6) mol/L and 1.2 x 10(-5) mol/L, respectively. The electrode shows good sensitivity, selectivity and stability, and has been applied to the determination of DA and AA simultaneously in samples with satisfactory results. 相似文献
6.
锡(Ⅳ)-3,4-二羟基苯甲酸-钒(Ⅳ) 体系极谱吸附催化波的研究 总被引:1,自引:0,他引:1
在含有 3.6×10-3mol/L 的 VOSO4、6.0×10-5mol/L 的 3,4-二羟基苯甲酸(DHBA)、 0.1mol/L 的甲酸盐缓冲溶液(pH3.3)体系中,Sn(Ⅳ)-DHBA 络合物产生一灵敏的吸附平行催化波,峰电位在 -0.52 V(vs.SCE).二次导数波高与锡浓度在 3.4×10-10~5.1×10-7mol/L 范围内呈良好线性关系.检出限达浓度 2×10-10mol/L .研究了催化波的性质和电极反应机理.方法已应用于罐头食品中微量锡的测定. 相似文献
7.
应用循环伏安法、微分脉冲伏安法对多菌灵在破碳电极上的电化学行为及其测定进行了研究。在pH=9.0的2mol/L NH3-NH4Cl底液中,对其进行循环伏安扫描,发现于0.61V(vs.Ag/AgCl)产生一灵敏的氧化峰。微分脉冲伏安法殉菌灵的检测限为4×10^-8mol/L。多菌灵的浓度在5.0×10^-7 ̄1.0×10^-5mol/L间与微分脉冲伏安峰电流呈线性关系(r=0.9942)。对于1× 相似文献
8.
铅-茜素紫-邻菲罗啉体系的极谱行为及其应用 总被引:4,自引:0,他引:4
用线性扫描示波极谱法研究了 Pb( ) -茜素紫 -邻菲罗啉体系的伏安行为 ,发现在含有 0 .1 mol/L KCl,p H 4.70的 HAc- Na Ac缓冲溶液中 Pb( ) -茜素紫 -邻菲罗啉体系产生一灵敏的极谱吸附波 ,其峰电位为 - 0 .56V( vs.SCE) ,峰电流与铅 ( )的浓度在 8× 1 0 - 8~ 2× 1 0 - 6 mol/L范围内呈线性关系 ,检出限为 5× 1 0 - 8mol/L;研究了电极反应机理 ,并用建立的方法测定了皮蛋中的铅含量。 相似文献
9.
Snezana D Nikolic Jelena J Mutic Aleksandar D Lolic Dragan D Manojlovic 《Analytical sciences》2005,21(5):525-529
A rapid, selective, and sensitive kinetic flow-injection method for iodide content determination with amperometric detection on a platinum electrode was developed. The method is based on the catalytic effect of iodide on the Mn3+ reaction with As3+ in the presence of sulfuric acid. The calibration curve was linear in the concentration range from 5.0 x 10(-7) to 1.0 x 10(-4) mol/L iodide. The limit of detection (LOD) was found to be 5.0 x 10(-9) mol/L iodide. The relative standard deviations (RSD) were 1.68% and 3.03% for 1.0 x 10(-3) mol/L standard and 1.0 x 10(-6) mol/L iodide solution (n = 6), respectively. The method has been successfully applied for determination of iodide in waters, table salts, fodder, organic substances and human blood sera. The results were compared with those obtained by a standard AOAC (Association of Official Analytical Chemists) method, as well as with those obtained by a kinetic spectrophotometric procedure for determination of iodide. 相似文献
10.
A voltammetric determination of adriamycin (ADM) at a carbon paste electrode (CPE) in the presence of cetyltrimethylammonium bromide (CTAB) is described. ADM strongly adsorbs on the surface of the electrode by the adsorption of CTAB, thereby affecting the reduction current. This method provides a detection limit below 10(-10) mol/L for ADM. The experimental parameters, which influence the voltammetric responses of ADM, e.g. the pH value, variety and concentration of surfactants and the scan rate, were optimized. The reduction peak current changes linearly with the ADM concentration over the range from 2.5 x 10(-8) mol/L to 5 x 10(-6) mol/L. The detection limit is 4 x 10(-10) mol/L for an accumulation time of 3 min. The coefficient of variation, determined at 4 x 10(-6) mol/L ADM, is 3.0% (n = 8). Using this method, ADM in the patient's urine samples, which undergoes active ADM chemotherapy, was determined. 相似文献