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101.
《Analytical letters》2012,45(9):1481-1490
A simple and sensitive electrochemical method is described for the determination of the cholesterol-reducing drug ezetimibe in aqueous solution. A glassy carbon electrode, modified with multiwalled carbon nanotubes and sodium dodecylsulphate was used as the working electrode. Ezetimibe yields a well-defined anodic peak at the surface of the electrode in an aqueous solution of pH 13. A linear amperometric calibration curve was obtained in the range of 1.2–78 μM (0.5–32.0 μg/mL) of ezetimibe, with a sensitivity of 88.6 nA/μM and a detection limit of 300 nM (0.12 μg/mL). The sensor was applied successfully to the determination of ezetimibe in pharmaceutical preparations. 相似文献
102.
研制了以麦芽糊精作为酪氨酸酶的激活剂 ,采用Nafion117膜抗阴离子干扰 ,聚乙烯亚胺 (PEI)作包埋剂以抗阳离子干扰的酪氨酸酶碳糊电极。工作电位为 - 10 0mV [vs.Hg/Hg2 Cl2(s) ],pH为 5 .4 0 ,测量时间为 1.0min。在此测量条件下 ,电极对苯酚的检出限为 5 .0× 10 - 8mol·L- 1,线性范围为 2 .0× 10 - 7~ 5 .0× 10 - 5mol·L- 1,RSD为 1.2 %。用所研制电极测定炼油废水中酚的含量 ,加标回收率为 10 0 .7%。 相似文献
103.
A novel stopped flow injection—amperometric (sFI-Amp) procedure for determination of chlorate has been developed. The reaction of chlorate with excess potassium iodide and hydrochloric acid, forming iodine/triiodide that is further electrochemically reduced at a glassy carbon electrode at +200 mV versus Ag/AgCl electrode is employed. In order to increase sensitivity without using of too high acid concentration, promoting of the reaction by increasing reaction time and temperature can be carried out. This can be done without increase of dispersion of the product zone by stopping the flow while the injected zone is being in a mixing coil which is immersed in a water bath of 55 ± 0.5 °C. In a closed system of FIA, a side reaction of oxygen with iodide is also minimized. Under a set of conditions, linear calibration graphs were in the ranges of 1.2 × 10−6-6.0 × 10−5 mol l−1and 6.0 × 10−5-6.0 × 10−4 mol l−1. A sample throughput of 25 h−1 was accomplished. Relative standard deviation was 2% (n = 21, 1.2 × 10−4 mol l−1 chlorate). The proposed sFI-Amp procedure was successfully applied to the determination of chlorate in soil samples from longan plantation area. 相似文献
104.
105.
《Electroanalysis》2005,17(13):1187-1191
A disposable electrochemical detector arrangement for capillary electrophoresis has been developed. The detection system consists of an assembly of a fused silica capillary and a microfiber electrode which are fixed in a proper position by sealing this configuration with the help of thermal lamination. The detector design is easy to prepare and inexpensive. Therefore it is used as a disposable device which can be replaced by a new one if any degradation of the performance characteristics occurs. The parameters influencing the detection performance were studied and optimized using nonaqueous capillary electrophoresis and ferrocene derivatives as model compounds. The practical utility was demonstrated by studying the separation and detection of water‐resistant dye compounds. 相似文献
106.
《Electroanalysis》2017,29(9):2114-2124
A novel and sensitive amperometric biosensor for L‐lysine determination based on a glassy carbon electrode (GCE) modified with graphene (GR) and redox polymer poly(vinylferrocene) (PVF) was constructed. L‐lysine‐α‐oxidase was immobilized onto the modified GCE by a glutaraldehyde/bovine serum albumin cross‐linking procedure. SEM, CV and EIS were used for the characterization of the surface morphology and stepwise fabrication processes of PVF/GR composite. Optimal composition of the biosensor and experimental conditions that affect the performance of the biosensor are discussed. The effect of buffer pH on biosensor response was studied in detail over a wide pH range. L‐lysine biosensor displayed a linear range of 9.9×10−7 ‐ 3.1×10−4 M with a low detection limit of 2.3×10−7 M and KM app value of 0.4 mM. The L‐lysine biosensor was tested using pharmaceutical sample and cheese with satisfactory results. 相似文献
107.
Liza Rassaei Frank MarkenMika Sillanpää Mandana AmiriCiprian Mihai Cirtiu Markus Sillanpää 《Trends in analytical chemistry : TRAC》2011,30(11):1704-1715
We review the state-of-the-art application of nanoparticles (NPs) in electrochemical analysis of environmental pollutants. We summarize methods for preparing NPs and modifying electrode surfaces with NPs. We describe several examples of applications in environmental electrochemical sensors and performance in terms of sensitivity and selectivity for both metal and metal-oxide NPs. We present recent trends in the beneficial use of NPs in constructing electrochemical sensors for environmental monitoring and discuss future challenges.NPs have promising potential to increase competitiveness of electrochemical sensors in environmental monitoring, though research has focused mainly on development of methodology for fabricating new sensors, and the number of studies for optimizing the performance of sensors and the applicability to real samples is still limited. 相似文献
108.
A poly-
-histidine(PLH)-copper(II) complex can be used as an alternative biocatalyst in an O2 detection-type amperometric enzyme-less
-ascorbate (AsA) sensor. The PLH–Cu(II) membrane was simply prepared by entrapping the PLH in polyacrylamide gel and subsequent treatment of the gel with CuCl2 solution. This enzyme-less biosensor can be used over a relatively wide pH region from 4 to 11 and enables precise determination of AsA (RSD less than 3%, n=10) at pH 7.0. The fundamental performance characteristics (sensitivity, response time, and linear range) of this PLH–Cu(II)-based sensor is comparable to those of a native ascorbate oxidase-based sensor. Unfortunately, the selectivity is inherently rather low and, as a result, the response was degraded in the presence of higher concentrations (more than mM order) of quinones. However, reducing sugars caused no interference and the sensor could be used to detect AsA in some fruits and drinks. This enzyme-less sensor has excellent stability for at least 3 months of repeated analysis (more than 300 samples) without loss of ordinal activity. 相似文献
109.
Simple, strip-type sensors based on 7,7,8,8-tetracyanoquinodimethane-modified graphite were prepared using screen printing techniques. The electrochemical strips operated at low potentials [50 mV at pH 7.0 or 100 mV at pH 4.8 vs. Ag/AgCl (printed)] and had a sensitivity of 3.5–7.1 μA 1 mmol?1L-ascorbic acid. Determination of ascorbic acid concentration was achieved in 30 s and required samples of ca. 30 μl. The current output of the electrodes was found to be relatively insensitive to variations in pH over the range 5.0–8.5. Between 15 and 35 °C, the temperature coefficient was 2.7% °C?1. The printed electrodes were suitable for single determinations but demonstrated adequate stability for periodic re-use. The ascorbic acid concentration in the juice of fresh fruit was determined using the electrochemical printed electrodes and a commercially available enzymatic test kit. Close agreement was observed between the two methods [r=0.9997 (n=12),slope=0.9798]. The limit of detection using the printed sensor for real samples was calculated as 4mg l?1(22 μM). 相似文献
110.
An amperometric enzyme electrode for glucose was prepared by incorporating poly (ethylene glycol)-modified glucose oxidase and cobalt octaethoxyphthalocyanine [CoPc(OEt)8], a new mediator, into a carbon paste matrix. The polymer-modified enzyme exhibited a higher activity than the native enzyme in the hydrophobic carbon paste medium. CoPc(OEt)8 could oxidize the enzyme at more negative potentials than unsubstituted cobalt phthalocyanine (CoPc). Further, the CoPc(OEt)8-mediated enzyme electrode showed a high stability: the electrode response to glucose did not decrease for at least 4 weeks (or for 700 assays), whereas the glucose response from a CoPc-mediated enzyme electrode fell to half of the initial value within 2 weeks (or after 300 assays). CoPc(OEt)8, a paraffin-oil soluble derivative of CoPc, incorporated in the bulk of carbon paste, diffused towards the electrode surface so as to renew continuously the electrode surface, which resulted in the high stability of the new mediator-based enzyme electrode. 相似文献