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 共查询到19条相似文献,搜索用时 93 毫秒
1.
在0.10 mol/L的K2HPO4-NaH2PO4(pH8.5)缓冲液中,使用JP-303极谱分析仪,靛玉红在碳糊电极(CPE)上有一灵敏的吸附伏安还原峰,峰电位为-0.60 V(vs.SCE)。该还原峰的二阶导数峰电流与靛玉红的浓度在8.0×10^-9-8.0×10^-7mol/L(富集90 s)范围内呈良好的线性关系,相关系数为0.9976,检出限为4.0×10^-9mol/L(S/N=3,富集110 s)。探讨了靛玉红在碳糊电极上的伏安性质和电极反应机理,并应用于中草药大青叶中靛玉红含量的测定。  相似文献   

2.
本文提出了以十六烷基三甲基溴化铵修饰碳糊电极(CTAB/CPE)直接测定尿酸(UA)的新方法,用线性扫描伏安法(LSV)研究尿酸的电化学行为。在0.1mol/L磷酸盐缓冲溶液(PBS,pH=7.4)中,尿酸在CTAB/CPE上于0.160V处产生一个灵敏的氧化峰,氧化峰电流Ip与尿酸浓度(CuA)在1.0×10^-5—1.0×10^-3mol/L范围内呈良好的线性关系,相关系数为0.9940,检出限为1.0×10^-6mol/L。该方法简单实用,可以直接用于人体尿液中尿酸的检测。  相似文献   

3.
电化学法研究橙黄Ⅳ和溶菌酶的相互作用   总被引:1,自引:0,他引:1  
在pH 11.00的NH3-NH4Cl缓冲溶液中,橙黄Ⅳ与溶菌酶能形成一种橙黄色的超分子复合物。用线性扫描二阶导数极谱法对该体系进行了研究,复合物的形成使橙黄Ⅳ的还原峰电位不变,峰电流下降,并且该峰电流的下降值同所加的溶菌酶的浓度在一定范围内呈线性关系。用于溶菌酶的测定,在1.6×10^-9-1.0×10^-8mol/L,1.0×10^-8-8.0×10^-8mol/L,9.0×10^-8-1.6×10^-7mol/L三段范围内呈线性关系,检出限为4.0×10^-10mol/L,进而对模拟样品进行分析,并对结合反应机理进行初步的探讨。  相似文献   

4.
用微分脉冲伏安(DPV)法研究了利尿剂类药物布美他尼在玻碳电极上的电化学行为。在pH2.87的B-R缓冲液中,布美他尼在+0.896V(vs.SCE)电位处产生一个阳极氧化峰,其峰电流与布美他尼的浓度在6.0×10^-8—2.5×10^-5mol/L的范围内呈良好的线性关系,检出限(3σ/K)为2.4×10^-8mol/L。将该法应用于布美他尼实际药片及模拟尿样的测定,结果令人满意。初步探讨了布美他尼的电化学机理。  相似文献   

5.
研究了抗癌药物诺必擂停在玻碳电极上的电化学行为及其反应机理,建立了一种灵敏的测定诺必擂停的分析方法。实验结果表明,在pH 2.0的磷酸盐缓冲溶液中,诺必擂停在-0.905 V电位处产生灵敏的还原峰,该还原峰电流与诺必擂停的浓度在8.21×10^-6-1.09×10^-4mol/L范围内呈现良好的线性关系(r=0.9923),检出限为5.47×10^-6mol/L。该法已用于人血清中诺必擂停的测定,回收率在94.5%-104.4%之间。  相似文献   

6.
电化学活化预处理玻碳电极伏安法测定苯胺   总被引:1,自引:0,他引:1  
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。  相似文献   

7.
N-乙酰-L-半胱氨酸在咖啡酸修饰碳糊电极上的电催化氧化   总被引:1,自引:1,他引:0  
研究了N-乙酰-L-半胱氨酸(N-acetyl-L-cysteine,NAC)在咖啡酸(CFA)修饰碳糊电极(CFA/CPE)上的电催化行为。结果表明,NAC在裸碳糊电极(CPE)上的直接电化学氧化过程十分迟缓,而CFA/CPE对NAC的电化学氧化具有良好的催化作用。用循环伏安法(CV)、计时电流法(CA)测定了NAC在CFA/CPE上的电极过程动力学参数。电荷传递系数α=0.79,电催化氧化反应速率常数k=(4.40±0.10)×10^3(mol.L^-1)^-1.s^-1。用微分脉冲伏安法(DPV)测得催化氧化峰电流与NAC浓度在1.0×10^-6~7.5×10^-4mol.L^-1范围内呈良好的线性关系,线性回归方程为Ipa(μA)=4.075c(mmol.L^-1)+2.671,r=0.9988,检出限为1.7×10^-7mol.L^-1。用该方法对市售药品富露施中的NAC含量进行测定,结果令人满意。  相似文献   

8.
对氯酚在碳纳米管修饰玻碳电极上的电化学行为研究   总被引:1,自引:0,他引:1  
研究了对氯酚在多壁碳纳米管修饰玻碳电极(MWNTs/GC)上的电化学行为。MWNTs/GC电极对对氯酚具有良好的电催化作用,相比玻碳电极对氯酚的氧化峰电位负移76 mV,峰电流达到玻碳电极上的8倍。通过线性扫描伏安法研究了富集时间、溶液pH和扫描速率对对氯酚氧化的影响。并采用计时电流法研究了氧化峰电流与对氯酚的浓度关系,结果显示峰电流与对氯酚的浓度在2.0×10^-7-2.0×10^-4mol/L范围内呈良好线性关系,检出限为8.8×10-8mol/L(S/N=3)。放置7 d后,对氯酚在碳纳米管上的峰电流仍能达到最初电流的96.2%,表明电极的稳定性较好。  相似文献   

9.
米托蒽醌分子印迹聚邻氨基酚敏感膜传感器的研制   总被引:2,自引:0,他引:2  
在弱酸性条件下,在金电极上以邻氨基酚为单体和交联剂,米托蒽醌为模板分子,用循环伏安法电聚合成米托蒽醌分子印迹聚邻氨基酚敏感膜传感器。该传感器对米托蒽醌具有良好的选择性和敏感度,米托蒽醌浓度分别在2.0×10^-7—1.0×10^-5mol/L及1.0×10^-5—5.0×10^-5mol/L范围内与峰电流减小量呈线性关系,检出限为1.2×10^-7mol/L。本文同时对分子印迹膜的结构和性能进行了探讨与研究。  相似文献   

10.
碱性条件下,铁氰化钾氧化鲁米诺产生化学发光,黄藤素对该体系的化学发光信号具有显著的增强作用。基于此,建立了一种直接测定黄藤素的流动注射化学发光分析新方法。该方法的线性范围为6.0×10-10-3.0×10^-8mol/L(r=0.9956)和3.0×10^-8-3.0×10^-6mol/L(r=0.9981),检出限为2.5×10^-10mol/L(3σ)。对1.0×10^-9mol/L和1.0×10^-7mol/L的黄藤素连续平行测定11次,其相对标准偏差分别为3.5%和0.73%。该方法用于药物和体液中黄藤素的分析,回收率在96%-102%之间。  相似文献   

11.
运用循环伏安法(CV),计时库仑法(CC),计时电流法(CA)研究了萘乙酸(NAA)在玻碳电极(GCE),多壁碳纳米管修饰玻碳电极(MWCNTs/GCE)和多壁碳纳米管-离子液体修饰玻碳电极(MWCNTs-IL/GCE)上的电化学行为及电化学动力学性质.实验结果表明,NAA在GCE电极上于1.00V附近有一不可逆氧化峰...  相似文献   

12.
Cyclic voltammetry and potentiostatic coulometry were used to study the electrochemical oxidation of thiourea in aqueous solutions of nitric acid, nitric acid—ammonium nitrate, and ammonium nitrate—ammonium hydroxide and in acetonitrile. These studies were carried out at glassy carbon and/or platinum working electrodes. In acetonitrile, the cyclic voltammograms show one oxidation peak at + 0.6 V and a reduction peak at —0.1 V. In aqueous solutions up to about pH 6, there is a second oxidation peak at 1.3 V which is irreversible and its height is sensitive to acidity. These experiments have confirmed that in acidic and neutral solutions the oxidation of thiourea proceeds via a slow 1-e transfer reaction producing a radical [(NH2)2—C—S]+. Further direct oxidation of this radical takes place only at higher potentials (ca. 1.2 V) and involves hydration and protontransfer equilibria. Otherwise, C,C'-dithiodiformamidinium ion is formed by a fast dimerization reaction. Coulometric and chronopotentiometric measurements have shown that in strong acid the second oxidation step involves one electron, while at lower acidities the further oxidation involving three (and possibly five) electrons proceeds in two (or three) steps of very similar potential.  相似文献   

13.
A reliable and reproducible method for the determination of uric acid in urine samples has been developed. The method is based on the modification of a glassy carbon electrode by 3-acetylthiophene using cyclic voltammetry. The poly(3-acetylthiophene) modified glassy carbon electrode showed an excellent electrocatalytic effect towards the oxidation of uric acid in 0.1 m phosphate buffer solution (PBS) at pH 7.2. Compared with a bare glassy carbon electrode (GCE), an obvious shift of the oxidation peak potential in the cathodic direction and a marked enhancement of the anodic current response for uric acid were observed. The poly(3-acetylthiophene)/GCE was used for the determination of uric acid using square wave voltammetry. The peak current increased linearly with the concentration of uric acid in the range of 1.25 x 10(-5)-1.75 x 10(-4) M. The detection limit was 5.27 x 10(-7) M by square wave voltammetry. The poly(3-acetylthiophene)/GCE was also effective to determine uric acid and ascorbic acid in a mixture and resolved the overlapping anodic peaks of these two species into two well-defined voltammetric peaks in cyclic voltammetry at 0.030 V and 0.320 V (vs. Ag/AgCl) for ascorbic acid and uric acid, respectively. The modified electrode exhibited stable and sensitive current responses toward uric acid and ascorbic acid. The method has successfully been applied for determination of uric acid in urine samples.  相似文献   

14.
在0.01 mol.L-1磷酸盐缓冲溶液(pH 7.4)中,用循环伏安法和方波伏安法研究了丹酚酸B与牛血清白蛋白相互作用前后在DNA修饰玻碳电极上的电化学行为。实验表明,丹酚酸B在此修饰电极上于0.100 V处产生良好的氧化峰,加入牛血清白蛋白后,丹酚酸B的电子转移系数α和表观电子传递速率常数ks均发生了变化,氧化峰电位正移,峰电流减小。根据氧化电流的变化求得丹酚酸B和牛血清白蛋白相互作用的结合常数β=1.00×108L.mol-1,结合数m=1.71,表明丹酚酸B与牛血清白蛋白生成了结合比约为2∶1的非电活性复合物。该结果与荧光光谱法的研究结果一致。  相似文献   

15.
采用Hummers法制备了纳米石墨烯,并将该纳米材料分散在蒸馏水中得到悬浮液,取5μL的悬浮液滴涂在玻碳电极表面,制备石墨烯修饰电极。用循环伏安法研究了在pH 4.0磷酸盐电解质中,在-0.4~0.8V(vs.Ag/AgCl)电位范围内,抗坏血酸在修饰电极上的电化学行为。结果表明:抗坏血酸在修饰电极上在0.173V处可见明显的氧化峰,且氧化峰电流显著高于在裸玻碳电极上的氧化峰电流;并可有效排除肾上腺素、尿酸、多巴胺等物质的干扰。据此提出了用循环伏安法测定抗坏血酸的方法。抗坏血酸的线性范围为8.00×10-6~1.0×10-3 mol.L-1,检出限(3S/N)为1.0×10-7 mol.L-1。方法用于维生素C片的分析,回收率在96.3%~104.4%之间。  相似文献   

16.
A novel film electrode for the voltammetric determination of tyrosine has been constructed based on electropolymerization of L-serine on a glassy carbon electrode. Voltammetric behaviour of tyrosine on the poly-L-serine film electrode was investigated with cyclic voltammetry and linear sweep voltammetry, and electrochemical parameters were calculated from chronocoulometry. In optimal conditions, the oxidation peak current of tyrosine on the poly-L-serine film electrode was enhanced greatly. A sensitive oxidation peak at 0.90 V was employed to determine tyrosine. A linearity between the oxidation peak current and the tyrosine concentration was obtained in the range of 3.0 x 10(-7) to 1.0 x 10(-4) mol L(-1) with a detection limit of 1.0 x 10(-7)mol L(-1). The practical application of the film electrode in the determination of tyrosine in a commercial amino acid oral solution demonstrated that it has good selectivity and high sensitivity.  相似文献   

17.
采用微电极循环伏安法和吸附转移溶出伏安法研究了单链多聚腺嘌呤核苷酸Poly(A)在金电极上的伏安行为。重点了考察了Poly(A)的吸附和氧化过程。发现Poly(A)分子在金电极表面能够形成多种状态的特性吸附。影响吸附态和吸附强度的主要因素是吸附电势, 吸附时间和溶液浓度。在负电位区, 随着吸附时间(t~s)的变化, Poly(A)分子在金电极表面发生不同状态的以腺嘌呤碱基为吸附位点的强吸附, 这种以腺嘌呤碱基吸附的Poly(A)分子能够在零伏附近给出很强的氧化电流峰和对应的还原峰。  相似文献   

18.
The electrochemical oxidation of thrombin on the surface of carbon screen printed electrodes was studied. The electrochemical activity of thrombin was predicted, using bioinformation analysis, based on the data about the electrochemical properties of amino acids. The number of potentially electroactive amino acid residues, namely, tyrosine (Tyr), tryptophan (Trp), cysteine (Cys), histidine (His), methionine (Met), and cystine (Cys-Cys) located on the protein surface and orientated by their electroactive groups toward the electrode surface, i.e., accessible for electrochemical oxidation was calculated. The theoretical data were confirmed experimentally by cyclic and square-wave voltammetry. The available data on the protein structure allowed us to attribute the recorded electrochemical signals of thrombin oxidation to certain types of amino acid residue: the oxidation peak with a potential maximum at 0.7–0.8 V (vs. Ag/AgCl) was attributed to the oxidation of the Trp and Tyr residues; the wave in the range 1.0–1.2 V, to the oxidation of His; and the wave at 1.2–1.5 V, to the oxidation of Met and Cys-Cys. The electroanalysis based on the oxidation peak of the Tyr and Trp amino acid residues allowed to detect thrombin up to the concentration of 10–7 M. The suggested strategy for predicting the electrochemical activity can be used for investigating the properties of many other proteins and peptides and serve as a basis for their quantitative determination when developing various sensor and biosensor devices.  相似文献   

19.
《Electroanalysis》2003,15(21):1693-1698
The voltammetric behaviors of uric acid (UA) and L ‐ascorbic acid (L ‐AA) were studied at well‐aligned carbon nanotube electrode. Compared to glassy carbon, carbon nanotube electrode catalyzes oxidation of UA and L ‐AA, reducing the overpotentials by about 0.028 V and 0.416 V, respectively. Based on its differential catalytic function toward the oxidation of UA and L ‐AA, the carbon nanotube electrode resolved the overlapping voltammetric response of UA and L ‐AA into two well‐defined voltammetric peaks in applying both cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which can be used for a selective determination of UA in the presence of L ‐AA. The peak current obtained from DPV was linearly dependent on the UA concentration in the range of 0.2 μM to 80 μM with a correlation coefficient of 0.997. The detection limit (3δ) for UA was found to be 0.1 μM. Finally, the carbon nanotube electrode was successfully demonstrated as a electrochemical sensor to the determination of UA in human urine samples by simple dilution without further pretreatment.  相似文献   

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