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1.
A mesoporous zirconia modified carbon paste electrode was developed for electrochemical investigations of methyl parathion (MP, Phen‐NO2). The significant increase of the peak currents and the improvement of the redox peak potential indicate that mesoporous zirconia facilitates the electronic transfer of MP. The oxidation peak current was proportional to the MP concentration in the range from 1.0×10−8 to 1.0×10−5 mol L−1 with a detection limit of 4.6×10−9 mol L−1 (S/N=3) after accumulation under open‐circuit for 210 s. The proposed method was successfully applied to the determination of MP in apple samples. 相似文献
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CarbonPasteElectrodeModifiedbySurfactantforAnodicStrippingVoltammetricDeterminationofSulphadiazineZhangZheng-qi;ChenZhan-guan... 相似文献
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丁二酮肟修饰碳糊电极阳极溶出伏安法测定痕量铋 总被引:1,自引:0,他引:1
报道了用丁二酮肟修饰碳糊电极测定微量铋的电分析方法。Bi~(3+)通过与电极表面的丁二酮肟作用而富集在电极表面,同时在-0.40 V(vs.SCE)还原成零价,当电极电势从-0.40 V向0.40 V扫描时,被还原的铋从电极表面溶出,在0.03 V出现一个十分灵敏的阳极溶出峰。优化了各种实验参数,如支持电解质的选择及pH值、丁二酮肟的用量、富集电位及时间等。修饰电极测定铋的线性范围为1×10~(-9)~1×10~(-6)mol/L。富集6 min后检出限可达4×10~(-10)mol/L。该方法简便快速,灵敏度高,分析成本低廉,并成功应用于实际水样中微量铋的测定。 相似文献
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《Electroanalysis》2003,15(22):1751-1755
A sensitive, selective and economic stripping voltammetry is described for the determination of trace amounts of zirconium at a morin‐modified carbon paste electrode (morin‐MCPE). Zirconium(IV) can be preconcentrated on the surface of the morin‐MCPE due to forming the Zr(IV)–morin complex. The complex produces two second‐order derivative anodic peaks at 0.69 V (vs. SCE) and 0.75 V when linear‐scanning from 0.0 to 1.0 V. The optimum analytical conditions are: 2.2 mol L?1 HCl, 0.0 V accummulation potential, 90 s accummulation time, 250 mV s?1 scan rate. A linear relationships between the peak currents at 0.75 V and the Zr(IV) concentration are in the range of 2.0×10?8 to 3.0×10?6 mol L?1. The detection limit is 1.0×10?8 mol L?1 (S/N=3) for 120 s accumulation. The RSD for determination of 4.0×10?7 mol L?1 Zr(IV) is 4.8% (n=8). The proposed method has been applied to determine zirconium in ore samples, unnecessarily extracted. 相似文献
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《Electroanalysis》2006,18(22):2218-2224
This article deals with the development of a method for the determination of osmium at a carbon paste electrode (CPE) modified with cationic surfactants of the quaternary ammonium salt type; namely, cetyltrimethylammonium bromide (CTAB) and 1‐(ethoxycarbonyl)‐pentadecyltrimethyl‐ammonium bromide (Septonex); both being added in situ and serving for preconcentration of osmium via its hexachloroosmate(IV) anion. The proper electrochemical detection was performed by cathodic scanning in the differential pulse voltammetric mode. Optimization studies concerning important experimental parameters also included a specially performed potentiometric titration, helping to define the actual stoichiometry for the ion‐pairing process, the main principle and driving force of the accumulation step. In a chloride/acetate buffer based supporting medium and with Septonex as the modifier of choice, the reduction signal for osmium was found to be proportional to the Os(IV) concentration in a range from 5×10?9 to 5×10?7 mol L?1 with a limit of detection close to 5×10?9 mol L?1 (with preconcentration for 60 s). The method capable to determine Os(IV) in the presence of both Pt(IV) and Ir(III) was tested on model solutions as well as with real sample of industrial waste water (spiked with the analyte); both yielding the recovery rates within 88–99%. 相似文献
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用电化学沉积法将三聚氰胺修饰在玻碳电极上,应用此三聚氰胺修饰玻碳电极测定银时,试液在pH 4.6的乙酸-乙酸钠缓冲溶液中,在—0.45V处还原60 s,然后在0~+0.6V范围内扫描,使银离子从修饰电极上溶出,实现了水样中银离子的溶出伏安法测定,在+0.27V处可得银离子的氧化峰电位,银的浓度在6.0×10~(-9)~5.0×10~(-7)mol·L~(-1)范围内与其峰电流呈线性关系,检出限(3S/N)为1.0×10~(-9)mol·L~(-1)。方法用于实际水样中痕量银的测定,加标回收率在90.0%~96.0%之间。 相似文献
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碳糊电极吸附溶出伏安法测定游离钙 总被引:8,自引:0,他引:8
基于Ca(Ⅱ)-茜素红S(ARS)络合物在碳糊电极上的还原波,建立了吸附溶出伏安测定游离钙的新方法。在1.5×10-2mol/LKOH-2.0×10-5mol/LARS介质中,Ca(Ⅱ)-ARS络合物在碳糊电极上于-0.89V处产生一吸附还原波。当富集电位为.0.1V,富集时间90s,扫描速度为100mV/s时,该络合物单扫描阴极溶出峰的二阶导数峰电流与游离钙离子浓度在3.0×10-8~2.0×10-6mol/L范围内呈线性关系;检出限为9.4×10-9mol/L。在0.2mol/LHCl中清洗2min,该电极重现性良好。该方法可用于血清、牛奶和自来水中游离钙的测定。 相似文献
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Margarita Stoytcheva Roumen Zlatev Zdravka Velkova Velizar Gochev Alan Ayala Gisela Montero Benjamín Valdez 《Electroanalysis》2021,33(3):695-704
A laponite modified carbon paste electrode was prepared, characterized and applied for the 2,4-dichlorophenol (2,4-DCP) voltammetric determination. It takes advantage of the ability of laponite to adsorb phenols, as well as of its availability and very low cost. Kinetic and equilibrium data for 2,4-DCP adsorption by laponite in aqueous dispersions demonstrated that the adsorption process obeyed a pseudo first order kinetic model and was consistent with the formation of adsorbed multilayers on a surface with heterogeneous pore distribution. The composite paste electrode exhibited a heterogeneous surface with 65 % increased surface area and 27 % enhanced catalytic activity compared to the unmodified one. The adsorptive stripping voltammetric determination of 2,4-DCP at an electrode with an optimized graphite:laponite ratio of 55 : 15 w% using a 3 min accumulation time at pH 5.5 was found to be suitable for its quantification in the linear concentration range extended up to 50 μmol L−1 with a sensitivity of 0.56 μA L μmol−1 and a LOD of 0.2 μmol L−1 (S/N=3).The 2,4-DCP electrochemical response was not affected by the presence of some structurally similar phenols, like catechol and p-nitrophenol, while resorcinol, 2-chlorophenol, and 4-chlorophenol presented interferences. The results were validated by 2,4-DCP determination in spiked tap water. 相似文献
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聚苯基荧光酮修饰玻碳电极吸附溶出伏安法测定痕量汞 总被引:1,自引:0,他引:1
研究利用聚苯基荧光酮修饰玻碳电极测定痕量汞的溶出伏安法,在0.1 mol.L-1氨水-NH4Cl缓冲溶液中(pH 9.5),开路搅拌,Hg(Ⅱ)富集于修饰电极表面,通过介质交换至0.1mol.L-1盐酸溶液中,于-0.40 V还原后阳极化线性扫描,在0 V左右处获得一灵敏汞的溶出峰。其氧化峰电流与Hg(Ⅱ)浓度在9.0×10-8~8.0×10-7mol.L-1范围内呈线性关系,开路富集5 min,检出限达2.0×10-8mol.L-1。应用此方法于尿液中汞的测定,所得平均RSD值小于4.02%,回收率试验结果在98.4%~103.2%间。 相似文献
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Adsorption stripping voltammetry, a very sensitive electroanalytical method, was employed to determine reserpine, a kind of anti-hypertensive drug. In 0.1M phosphate buffer with a pH of 6.0, reserpine was accumulated at a multi-wall carbon nanotubes (MWNT)-modified glassy carbon electrode (GCE) surface under the condition of open-circuit. In the following anodic sweep from 0.20 to 1.00V, reserpine, adsorbed at the MWNT-modified GCE surface, was oxidized and yielded a sensitive oxidation peak at 0.64V. Due to its unique structure and extraordinary properties, MWNT shows a ten times higher accumulation efficiency toward reserpine, compared with a bare GCE. Hence, the amount of reserpine at the MWNT-modified GCE surface increases significantly, and finally the oxidation peak current improves greatly. The experimental conditions, such as supporting electrolyte, pH value, the amount of MWNT-DHP suspension, accumulation time and scan rate, were optimized for the measurement of reserpine, and a sensitive electroanalytical method was proposed for reserpine determination. The oxidation peak current varies linearly with the concentration of reserpine over the range of 2×10–8 to 1×10–5M, and the detection limit is 7.5×10–9M after 4min open-circuit accumulation. The relative standard deviation at 1×10–6M reserpine was about 4.7% (n=7), indicating excellent reproducibility. This new method was successfully demonstrated with reserpine injections and tablets. 相似文献
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《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
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The study of electrochemical behavior of amoxicillin (AMX), a β‐lactam antibiotic, is described on a multiwalled carbon nanotubes (MWCNTs) modified electrode by electrochemical impedance spectroscopy (EIS) and adsorptive stripping voltammetry for sensitive determination of AMX in pharmaceutical and human urine samples within a wide pH range from 2.0 to 10.0. Also, studies by Fe2O3 nanoparticles modified carbon paste electrode show that iron oxide impurities in the MWCNTs are not active sites for sensing of amoxicillin. Under optimized conditions, the oxidation peak has two linear dynamic ranges of 0.6–8.0 and 10.0–80.0 μM with a detection limit of 0.2 μM and a precision of <4%. 相似文献
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《Electroanalysis》2002,14(23):1615-1620
Electrochemically modified glassy carbon electrode (GCE) was used to study the electrochemical oxidation and detection of denatured single‐stranded (ss) DNA by means of adsorptive stripping voltammetry. The modification of GCE, by electrochemical oxidation at +1.75 V (vs.SCE) for 10 min and cyclic sweep between +0.3 V and ?1.3 V for 20 cycles in pH 5.0 phosphate buffer, results in 100‐fold improvement in sensitivity for ssDNA detection. We speculated that the modified GCE has a high affinity to single‐stranded DNA through hydrogen bond (specific static adsorption). Single‐stranded DNA can accumulate at the GCE surface at open circuit and produce a well‐defined oxidation peak corresponding to the guanine residues at about +0.80 V in pH 5.0 phosphate buffer, while the native DNA gives no signal under the same condition. The peak currents are proportional to the ssDNA concentration in the range of 0–18.0 μg mL?1. The detection limit of denatured ssDNA is ca. 0.2 μg mL?1 when the accumulation time is 8 min at open circuit. The accumulation mechanism of ssDNA on the modified GCE was discussed. 相似文献
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槲皮素化学修饰碳糊电极吸附溶出伏安法测定痕量铅 总被引:14,自引:0,他引:14
建立了用槲皮素修饰碳糊电极测定痕量铅的新方法 ,在 0 .1 0mol L甲酸盐缓冲液 (pH 4.3 )中 ,于 -0 .1 0V(vs.SCE)搅拌富集 ,再在 -0 .70V静止还原 40s后 ,阳极化扫描 ,于 -0 .42V左右获得一灵敏的铅阳极溶出峰。在最佳条件下 ,富集不同时间 ,其二次导数峰电流与Pb2 + 在 1 .0× 1 0 - 8~ 8.0× 1 0 - 7mol L和 2 .0× 1 0 - 9~ 6.0× 1 0 - 8mol L两个范围内呈线性关系 ,检出限为 8.0× 1 0 - 1 0 mol L(S N =3 )。同时初步探讨了电极反应机理。 相似文献
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A. J. Saleh Ahammad Subrata Sarker Md Aminur Rahman Jae‐Joon Lee 《Electroanalysis》2010,22(6):694-700
A selective and very simple electrochemical method, based on anodization of a glassy carbon electrode (GCE), was developed for the simultaneous detection of hydroquinone (HQ) and catechol (CT). It was found that the activated GCE showed an excellent catalytic behavior and enhanced reversibility towards the oxidation of both HQ and CT. The redox responses from the mixture of HQ and CT were easily resolved at an activated GCE. The detection limits for HQ and CT were calculated to be 0.16 and 0.11 μM, respectively. The activated GCE was successfully examined for real sample analysis with tap water and it showed a stable and reliable recovery data. 相似文献
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A voltammetric sensor for the determination of parathion has been developed based on the use of a poly(carmine) film electrode.
The reduction of parathion at the poly(carmine) modified glassy carbon electrode (GCE) is studied by cyclic voltammetry (CV)
and linear scan voltammetry (LSV). Parathion yields a well-defined reduction peak at a potential of −0.595 V on the poly(carmine)
modified GCE in pH 6.0 phosphate buffer solution (PBS). Compared with that on a bare GCE, the reduction peak current of parathion
is significantly enhanced. All the experimental parameters are optimized for the determination of parathion. The reduction
peak current is linear with the parathion concentration in the range of 5.0 × 10−8 to 1.0 × 10−5 mol L−1, and the detection limit is 1.0 × 10−8 mol L−1. 相似文献