电化学活化预处理玻碳电极伏安法测定苯胺

苯胺的电化学氧化产物可被富集在经电化学活化预处理的玻碳电极上,在稀硫酸溶液中,富集物于＋0.4～＋0．5V（vs．SCE）内产生一对峰形良好的氧化还原峰,利用该氧化还原峰建立了伏安法测定苯胺的方法。在最佳试验条件下,方法的线性范围为1×10^-7～1×10^-5mol·L^-1;当富集时间为5min和富集电位为＋1．2V（vs．SCE）时,方法的检出限达5×10^-8mol·L^-1。用此方法测定了工业废水和河水样品中苯胺类物质,测得结果与国家标准方法的测定结果一致。     

香兰素在电活化玻碳电极上的电化学行为及其伏安法测定

制备了电活化玻碳电极,并考察香兰素在该电极上的电化学行为。在优化的实验条件下,香兰素在该电极上有良好的电化学响应,其浓度在1.0×10-6～2.0×10-4mol.L-1范围内与氧化峰电流呈良好的线性关系。检测限(S/N=3)为6.7×10-7 mol.L-1。香兰素于电活化玻碳电极表面发生的电极反应是扩散控制的2电子2质子转移过程。该方法操作简便,重现性较好,并应用此法分析了巧克力中香兰素的含量。     

电化学活化玻碳电极吸附伏安法测定维生素K

维生素K类物质可在经电化学活化的玻碳电极上吸附富集并产生良好的伏安响应, 依此建立了吸附伏安法测定维生素K1和K3的方法. 在0.1 mol/L HCl的支持电解质中, 维生素K1在-0.025 V左右产生一对氧化还原峰, 其峰电流与浓度在1.1×10-6～2.2×10-5 mol/L范围内成良好的线性关系, 检出限为4.4×10-7 mol/L; 维生素K3则在+0.059 V左右产生一对氧化还原峰, 其线性范围为1.8×10-7～3.0×10-5 mol/L, 检出限为9.1×10-8 mol/L. 该方法可用于测定药品中的维生素K1和K3.     

磷酸盐活化玻碳电极应用于肾上腺素的伏安测定

采用循环伏安法制备了磷酸盐活化玻碳电极,研究了在pH 6.0磷酸盐缓冲介质中肾上腺素在磷酸盐活化玻碳电极上的电化学行为,建立了循环伏安法测定痕量肾上腺素的方法,该方法可有效地排除抗坏血酸对肾上腺素的干扰。在电位值为0.26V(vs.SCE)处,肾上腺素在磷酸活化玻碳电极上有一灵敏的氧化峰。肾上腺素浓度cEP在1.0×10-6～1.2×10-5 mol.L-1范围内与氧化峰电流ipa呈线性关系。检出限(3S/N)为3.0×10-7 mol.L-1。方法应用于肾上腺素注射液的分析,测得肾上腺素含量与标示值相符。用标准加入法测得方法的回收率为99.7%。     

吡哌酸在玻碳电极上的伏安测定

本文应用线性扫描伏安法，微分脉冲伏安法，循环伏安法对吡哌酸在ＧＣＥ上的伏安行为进行了研究，发现在磷酸盐缓冲溶液中＋１．２Ｖ左右有一氧化峰，ＰＰＡ的浓度２－１００μｇ／ｍｌ与峰电流呈良好的线性关系。测定了胶囊和片剂中ＰＰＡ的含量，ＲＳＤ２．１％，回收率在９７％－１０４％之间，方法操作简单快速。ＰＰＡ在ＧＣＥ上的电极反应属于不可逆过程。     

电活化玻碳电极差分脉冲伏安法测定水杨酸的研

采用循环伏安法和差分脉冲伏安法对水杨酸在电活化玻碳电极上的电化学行为进行研究.在pH7.0的PBS溶液中,将玻碳电极用恒电位法在+1.7V电位阳极氧化400 s.在0.2 mol·L- NaOH溶液中,水杨酸在0.602 V处有一良好的氧化峰,其氧化峰电流与扫描速率在0.02～0.2 V·s-1范围内呈良好线性关系,表...     

玻碳电极单扫伏安法测定药物的研究

玻碳电极单扫伏安法测定药物的研究朱俊杰，卢宗桂，李宣，李伯男，高鸿（南京大学化学系，南京２１０００８）关键词：单扫伏安法，玻碳电极，药物药物盐酸氯丙嗪和维生素Ｂ＿６片剂在中国药典中的测试方法均为分光光度法￣［１，２］，本文提出用伏安法来测定，结果满意...     

羟乙芦丁在玻碳电极上的阳极微分脉冲伏安法测定

本文对羟乙芦丁在玻碳电极上的阳极微分脉冲安行为进行了研究，发现在Ｎａ２ＨＰＯ４溶液中（ｐＨ＝８．９５）于＋０．６４Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）左右产生一个良好的阳极氧化伏安峰，浓度在５～６０ｍｇ／Ｌ之间与峰电流呈线性关系，不需分离直接测定了片剂中的羟乙芦丁含量。电极反应为扩散速率控制的不可逆可程。     

玻碳电极吸附伏安法测定痕量硫化物的研究

研究了利用玻碳电极吸附伏安法测定痕量硫化物的新方法。在含高铁离子的酸性溶液中,硫化物与对-氨基苯二甲基盐酸盐(p-ADAD)反应生成亚甲基蓝,采用线性扫描伏安法亚甲基蓝于-0.30 V(vs.SCE)在玻碳电极上出现灵敏的还原峰,峰电流与S2-浓度在0～25μg/mL范围内呈良好的线性关系。优化了实验条件,研究了电极反应机理。该方法具有灵敏、简便、快速、避免汞污染等特点。已成功用于多种水样中痕量硫化物的测定,回收率为98.0%～104.6%,结果令人满意。     

黄芩甙在玻碳电极上的电化学行为及其应用

用线性扫描伏安法(LSV)、循环伏安法(CV)和常规脉冲伏安法(NPV)等多种电化学方法研究了黄芩甙在玻碳电极上的电化学行为,并建立了尿样和血清样品中黄芩甙的微分脉冲伏安(DPV)测定法。实验结果表明:黄芩甙在玻碳电极上的吸附符合Frumkin吸附等温式,吸附自由能为-35.01kJ mol。采用整体电解法求得电极反应电子数为2,并结合Nernst方程式推导了反应机理。黄芩甙在玻碳电极上预富集后,在4.20×10-10～1.05×10-5mol L范围内分段呈线性关系,对5.60×10-7mol L黄芩甙溶液连续6次测定的RSD=2.0%,检出限为2.8×10-10mol L。     

Voltammetry determination of trace manganese with pretreatment glassy carbon electrode by linear sweep voltammetry

This paper described the determination of trace manganese using linear sweep voltammetry at a pretreatment glassy carbon electrode. The glassy carbon electrode pretreated by electrochemical method in the 0.1 mol l⁻¹ NaOH solution greatly improved the electrode responsibility in the determination of manganese(II). The barrier to the detection of low manganese concentration was overcome by means of autocatalytic effect of manganese oxide deposited on the electrode in advance. Under the optimum experiments condition (0.04 mol l⁻¹ NH₃-NH₄Cl buffer solution, pH 9.0), the linear range was 4×10⁻⁸ to 1×l0⁻⁶ mol l⁻¹ Mn(II) for linear sweep voltammetry and 1×10⁻⁹ to 4×10⁻⁸ mol l⁻¹ Mn(II) for convolution voltammetry. The relative standard deviation for 2×10⁻⁸ mol l⁻¹ Mn(II) is 3.4%. The proposed method is simple, rapid, sensitive and selective. It had been applied to the determination of trace manganese in samples with satisfactory results.     

Electrochemical determination of maltol in beverages with glassy carbon electrode and its silica sol-gel modified electrode

The electrochemical behavior of maltol on a glassy carbon (GC) electrode was investigated. The results were applied to differential pulse voltammetric determination of maltol in beverages pretreated by ultrafiltration. Under the optimum experimental conditions, the linear range is 1×10⁻⁵ to 6×10⁻⁴ mol l⁻¹ maltol and the relative standard deviation for 0.4 mmol l⁻¹ maltol is 0.6% (n=9). The detection limit was 5 μmol l⁻¹. Furthermore, silica sol-gel film on GC electrode could be used as suitable selective membrane, which integrated selective membrane on the electrode and substituted for the pretreatment of ultrafiltration. Under the above conditions, maltol was determined by semi-differential linear sweep voltammetry at a silica sol-gel modified GC electrode in the concentration range of 5×10⁻⁶ to 5×10⁻⁴ mol l⁻¹. The detection limit was 2 μmol l⁻¹ and the relative standard deviation for 0.1 mmol l⁻¹ maltol was 0.7% (n=7). The proposed method is of sensitivity, simplicity, rapidness and no contamination. It had been applied to the direct determination of maltol in beverages such as grape wines, drinks and beers without any pretreatment. The results obtained with the present method were satisfactory with those obtained by spectrophotometry. It could be used as a simple and practical method for the determination of the flavor enhancer maltol in beverages.     

Redox behavior of biofilm on glassy carbon electrode

Marine and freshwater biofilm usually shift the open circuit potential (OCP) of stainless steel towards the electropositive direction by + 450 mV vs SCE. The nature of oxide film and bacterial metabolism were also correlated with ennoblement process by various investigators. Glassy carbon electrode (GCE) was used in the present study and a shifting of potential in the positive side (+ 450 mV) was noticed. It indicates that biofilm contributes to the ennoblement process without any n/p-type semiconducting oxide film. The nature of the cathodic curve for the biofilm covered GCE is compared with the previous literature on the electrochemical behavior of stainless steel. The present study explains the oxidation and reduction peaks of biofilm covered GCE by cyclic voltammetry. Electrochemical impedance result reveals the diffusion process within the manganese biofilm. The present study confirms the previous investigations that the manganese biofilm rules the electrochemical behavior of materials and suggests that oxide film is not necessary to assist the ennoblement process.     

Sensitive voltammetric determination of tyrosine using multi-walled carbon nanotubes/4-aminobenzeresulfonic acid film-coated glassy carbon electrode

A chemically modified electrode is constructed based on the multi-walled carbon nanotubes (MWNTs)/4-aminobenzeresulfonic acid (4-ABSA) film-coated glassy carbon electrode. The electrocatalytic oxidation of tyrosine (Tyr) is investigated on the surface of the MWNTs/4-ABSA-modified electrode using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The prepared modified electrode shows voltammetric responses with high sensitivity and selectivity for Tyr in optimal conditions, which makes it very suitable for sub-micromolar detection of Tyr. A sensitive oxidation peak at +0.64 V is employed to determine Tyr. Good linear relationship between the oxidation peak current and the Tyr concentration in the range of 1 × 10⁻⁷ to 5 × 10⁻⁵ mol/L is obtained in phosphate buffer solution with pH 7.0. By use of modified electrode, the voltammetric detection limit for Tyr in DPV measurements is 8 × 10⁻⁸ mol/L (S/N = 3). Good sensitivity, selectivity and stability of the low-cost modified electrode make it very suitable for the determination of trace amounts of Tyr in pharmaceutical and clinical preparations.     

Voltammetric determination of quercetin at a multi-walled carbon nanotubes paste electrode

Quercetin can effectively accumulate at multi-walled carbon nanotubes-paraffin oil paste electrodes (CNTPE) and cause a sensitive anodic peak at around 0.32 V (vs. SCE) in a 0.10 M phosphate buffer solution (pH = 4.0). Under optimized conditions, the anodic peak current is linear to quercetin concentration in the ranges of 2.0 × 10^− 9−1.0 × 10^− 7 M and 1.0 × 10^− 7−2.0 × 10^− 5 M, and the regression equations are i_p (μA) = 0.0017 + 0.928c (μM, r = 0.999) and i_p (μA) = 0.183 + 0.0731c (μM, r = 0.995), respectively. This paste electrode can be regenerated by repetitively cycling in a blank solution for about 2 min. A 1.0 × 10^− 6 M quercetin solution is measured for 10 times using the same electrode regenerated after every determination, and the relative standard deviation of the peak current is 1.7%. The method has been applied to the determination of quercetin in hydrolysate product of rutin and the recovery is 99.2–102.6%. In comparison with graphite paste electrode, carbon nanotubes-nujol paste electrode and carbon nanotubes casting film modified glassy carbon electrode, the CNTPE gives higher ratio of signal to background current and better defined voltammetric peak.     

Electro-oxidation of herbicide halosulfuron methyl on glassy carbon electrode and applications

Halosulfuron methyl, a fast-acting herbicide and is absorbed into leaf tissue within 1-2 days and translocated through the vascular system, interrupting amino acid production within the plant, can be detected using glassy carbon electrode the technique of adsorptive stripping voltammetry. The adsorptive stripping voltammetric behavior of halosulfuron methyl was investigated in pH range 1.0-10.0. Halosulfuron methyl was irreversibly oxidized at a glassy carbon electrode. Electrochemical techniques including adsorptive stripping voltammetry and cyclic voltammetry were employed to study the oxidation mechanism. The experimental parameters such as the accumulation potential, accumulation time and frequency were optimized. The linear range, detection limit and quantification for halosulfuron methyl were evaluated by adsorptive stripping voltammetry. Under the optimized conditions, the peak current is linear to halosulfuron methyl concentration in the range 4.1-50.0 μg mL⁻¹. Limit of detection and limit of quantification were 1.23 and 4.10 μg mL⁻¹, respectively. The interference of inorganic species and other some pesticides on the voltammetric response have been studied. The applicability to spiked soil and natural water was described and the recoveries for the standards added are 103.8% and 108.2%, respectively. The method is successfully applied for the determination of halosulfuron methyl in commercial formulation.     

磷酸可待因在Nafion修饰玻碳电极上的伏安行为研究及测定

用循环伏安法和微分脉冲吸附伏安法对磷酸可待因在Nafion修饰玻碳电极上的伏安行为进行了研究。结果表明在 0 .1mol/LHCl底液中 ,磷酸可待因在 + 1 .0 6V处 (vs.SCE)产生一良好的氧化峰 ,磷酸可待因浓度在 5 .0× 1 0 - 7～2 .5× 1 0 - 5mol/L范围内与峰电流呈线性关系 ,检出限为 1 .3× 1 0 - 7mol/L。并分别对其单方药和复方药制剂进行了测定     

裸玻碳电极伏安测定甲氰咪胍

提出了裸ＧＣＥ不需任何处理测定甲氰咪胍的方法，浓度在３×１０＾－７－６×１０＾－５ｇ／ｍＬ，范围内与峰电流呈线性关系，ＲＳＤ为２．２％，回收率为９６％－１０２％。该方法操作简便快速，大多数金属离子和多种有机生化物质不干扰测定，方法用于片剂和加标尿样中甲氰咪胍的测定与药典方法对照，获得满意结果，并对电极反应进行了初步探讨。     

Selective determination of dopamine in the presence of high concentration of ascorbic acid using nano-Au self-assembly glassy carbon electrode

The cysteamine (CA) was bound onto surface of the pretreated glassy carbon electrode (GC) with cyclic voltammetry (CV). Gold nanoparticles were self-assembled to the electrode binding with cysteamine via strong AuS covalent bond to fabricate the nano-Au self-assembled modified electrode (nano-Au/CA/GC). The modified electrode was characterized with cyclic voltammetric and ac impedance methods. The electrochemical behavior of dopamine (DA) on the modified electrode was investigated with cyclic voltammetry and differential pulse voltammetry (DPV). A well-defined redox peaks of DA on the nano-Au/CA/GC electrode were obtained at E_pa = 0.175 V and E_pc = 0.146 V (vs. SCE), respectively. The peak current of DA is linear with the concentration of DA in the range of 1.0 × 10⁻⁸ mol L⁻¹ to 2.5 × 10⁻⁵ mol L⁻¹, with the correlation coefficient of 0.998. The detection limit is 4.0 × 10⁻⁹ mol L⁻¹ (S/N = 3). The modified electrode exhibited an excellent reproducibility, sensibility and stability for determination of DA in the presence of high concentration AA, and can be applied to determinate dopamine injection, with satisfied result.