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801.
802.
This work offers construction and comparative evaluation the performance characteristics of conventional polymer (I), carbon paste (II) and carbon nanotubes chemically modified carbon paste ion selective electrodes (III) for meclofenoxate hydrochloride are described. These electrodes depend mainly on the incorporation of the ion pair of meclofenoxate hydrochloride with phosphomolybdic acid (PMA) or phosphotungestic acid (PTA). They showed near Nernestian responses over usable concentration range 1.0 × 10−5 to 1.0 × 10−2 M with slopes in the range 55.15–59.74 mV (concentration decade)−1. These developed electrodes were fully characterized in terms of their composition, response time, working concentration range, life span, usable pH and temperature range. The electrodes showed a very good selectivity for Meclo with respect to a large number of inorganic cations, sugars and in the presence of the degradation product of the drug (p-chloro phenoxy acetic acid). The standard additions method was applied to the determination of MecloCl in pure solution, pharmaceutical preparations and biological samples. Dissolution testing was also applied using the proposed sensors. 相似文献
803.
《Analytical letters》2012,45(11):1735-1746
Abstract Nanoscale Pt/RuO2 colloid with carbon paste support was synthesized and used to prepare a modified electrode for phenol detection. The results showed that the Pt/RuO2 catalyst has high activity for electrooxidation of phenol with reduced intermediate polymerization due to its significantly low potential for phenol oxidation. The detection limit was as low as 10?9 mol L?1 for the polishable Pt/RuO2/C paste electrode with good reproducibility. 相似文献
804.
《Analytical letters》2012,45(7):1144-1157
Abstract The fabrication and analytical applications of two types of potentiometric sensors for the determination of ketoconazole (KET) are described. The sensors are based on the use of KET-molybdophosphoric acid (MPA) ion pair as electroactive material. The fabricated sensors include both polymer membrane and carbon paste electrodes. Both sensors showed a linear, stable and near Nernstian slope of 57.8 mV/decade and 55.2 mV/decade for PVC membrane and carbon paste sensors respectively over a relatively wide range of KET concentration (1 × 10?2 ? 5 × 10?5and 1 × 10?2 ? 1 × 10?6). The sensors showed a fast response time of < 30 sec and < 45 sec. A useful pH range of 3–6 was obtained for both types of sensors. A detection limit of 2.96 × 10?5M was obtained for PVC membrane sensor and 6.91 × 10?6 M was obtained for carbon paste sensor. The proposed sensors proved to have a good selectivity for KET with respect to a large number of ions. The proposed sensors were successfully applied for the determination of KET in pharmaceutical formulations. The results obtained are in good agreement with the values obtained by the standard method. 相似文献
805.
《Analytical letters》2012,45(16):2618-2630
A carbon paste electrode (CPE), modified with novel hydroquinone/TiO2 nanoparticles, was designed and used for simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA). The magnitude of the peak current for modified TiO2-nanoparticle CPE (MTNCPE) increased sharply in the presence of ascorbic acid and was proportional to its concentration. A dynamic range of 1.0–1400.0 μM, with the detection limit of 6.4 × 10?7 M for AA, was obtained using the DPV technique (pH = 7.0). The prepared electrode was successfully applied for the determination of AA, UA, and FA in real samples. 相似文献
806.
《Analytical letters》2012,45(20):2569-2579
Abstract Adsorptive/extractive accumulation of 1,2,3,4-tetrahydrocarbazole at a carbon paste electrode is used to improve the subsequent voltammetric measurement with respect to sensitivity and selectivity. By simply immersing the electrode in the 1,2,3,4-tetrahydrocarbazole solution for a given period of time, and then transferring it to a blank solution, high degree of selectivity is achieved. After 10 min preconcentration, a detection limit near 1.4×10-8M 1,2,3,4-tetrahydrocarbazole is obtained. Cyclic voltammetry is used to aid understanding the nature of the accumulation process. Applicability to measurements of other indole alkaloids and to analysis of urine samples is illustrated. 相似文献
807.
808.
用循环伏安法和线性扫描伏安法研究了头孢氨苄在碳糊电极上的电化学行为,考察了不同电解质溶液、pH以及扫描速率等的影响。实验表明:在2.0 mol·L-1HCl支持电解质中,头孢氨苄的降解产物在-0.45 V(vs.SCE)处的电化学还原反应为2电子与2质子参加的受吸附控制的不可逆过程。还原峰电流与头孢氨苄的浓度的平方根在1.8×10-8~3.0×10-4mol·L-1范围内呈良好的线性关系,回收率在95.7%~101.5%范围,检出限(S/N=3)为1.0×10-8mol·L-1。并探讨了头孢氨苄在电极上的反应机理。 相似文献
809.
《Analytical letters》2012,45(9):1750-1762
Abstract The interaction between clozapine (CLZ) as an orally administrated antipsychotic drug with double stranded calf thymus DNA (dsDNA) was investigated at electrode surface using differential pulse voltammetry (DPV). Activated carbon paste electrode (CPE) was modified with dsDNA and used for monitoring the changes of the characteristics peak of CLZ in 0.05 M acetate buffer (pH 4.3). The adsorptive stripping voltammetry on dsDNA‐modified carbon paste electrode (dsDNA‐CPE) was used for determination of very low concentration of CLZ. Under optimal conditions, the oxidation peak current is proportional to CLZ concentration in the range of 7×10?9?1.2×10?6 mol l?1 with a detection limit of 1.5×10?9 mol l?1 for 180 s accumulation time by DPV. The proposed dsDNA‐CPE was successfully used for determination of CLZ in human serum samples with recovery of 97.0±2.5%. 相似文献
810.
《Analytical letters》2012,45(10):1939-1950
Abstract An adsorptive stripping voltammetric (AdSV) method for the determination of organophosphorus insecticide chlorpyrifos at a bare carbon paste electrode (CPE) and clay modified carbon paste electrode (CMCPE) was developed. A systematic study of various experimental conditions, such as the pH, accumulation variables and composition of a modifier on the adsorptive stripping response, were examined by using differential pulse voltammetry. A significant improvement was observed in the sensitivity by using the present method with CMCPE. When CMCPE was used, a linear response was obtained over the concentration range 0.0001–2.0 ppm with lower detection limit of 0.00008 ppm, at an accumulation time of 80 s. The interference from other herbicides and ions on the stripping signal of the compound was also evaluated. The described method was applied to estimate the chlorpyrifos in environmental samples. 相似文献