共查询到20条相似文献,搜索用时 31 毫秒
1.
Nashwa M. H. Rizk 《Mikrochimica acta》2002,138(1-2):53-58
The construction and electrochemical response characteristics of poly(vinyl) chloride matrix membrane sensors for menadione
(vitamin K3) are described. Membranes incorporating the ion association complexes of menadione anion with bathophenanthroline nickel(II)
and iron(II) as electroactive materials show linear response for menadione over the range 10−1–10−5 M with anionic slopes of 58.2–51.4 mV per concentration decade. Both sensors exhibit fast response time (20–30 s), low detection
limit (2 × 10−5 M), good stability (4–6 weeks) and selectivity coefficient (10−1–10−3). Direct potentiometric determination of menadione under static and hydrodynamic mode of operations shows average accuracies
of 98.8 and 98.5% with relative standard deviations of 0.6% and 1.3%, respectively. Application of the method for the determination
of menadione in human plasma gives favourable results compared with those obtained by the standard spectrophotometric method.
Received February 26, 2001. Revision October 1, 2001. 相似文献
2.
The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode
were investigated. The electrode can enhance the electrochemical response of uric acid (UA), and the electrochemical reaction
of UA on the PCA electrode has been studied by cyclic voltammetry and differential pulse voltammetry. Some electrochemical
parameters, such as diffusion coefficient, standard rate constant, electron transfer coefficient and proton transfer number
have been determined for the electrochemical behavior on the PCA self-assembled monolayer electrode. The electrode reaction
of UA is an irreversible process, which is controlled by the diffusion of UA with two electrons and two protons transfer at
the PCA/Au electrode. In phosphate buffer (pH 5.0), the peak current is proportional to the concentration of UA in the range
of 6.0 × 10−5–7.0 × 10−4 mol L−1 and 2.0 × 10−5–7.0 × 10−4 mol L−1 for the cyclic voltammetry and differential pulse voltammetry methods with the detection limits of 5.0 × 10−6 and 3.0 × 10−6 mol L−1, respectively. The method can be applied to determine UA concentration in real samples. 相似文献
3.
Jun Yue Bai Liang Wang Hong Jing Wang Peng Fei Huang Yu Qing Zhao Sheng Di Fan 《Mikrochimica acta》2006,156(3-4):321-326
The electrochemical behavior of epinephrine (EP) at a mercaptoacetic acid (MAA) self-assembled monolayer modified gold electrode
was studied. The MAA/Au electrode is demonstrated to promote the electrochemical response of epinephrine by cyclic voltammetry.
The possible reaction mechanism is also discussed. The diffusion coefficient D of EP is 6.85 × 10−6 cm2 s−1. In 0.1 mol L−1 phosphate buffer (pH 7.20), a sensitive oxidation peak was observed at 0.177 V, and the peak current is proportional to the
concentration of EP in the range of 1.0 × 10−5–2.0 × 10−4 mol L−1 and 1.0 × 10−7–1.0 × 10−6 mol L−1. The detection limit is 5 × 10−8 mol L−1. The modified electrode is highly stable and can be applied to the determination of EP in practical injection samples. The
method is simple, quick, sensitive and accurate. 相似文献
4.
Determination of the effective components in traditional Chinese medicine is one of the key steps for its identification.
In this paper a novel and sensitive chemiluminescence (CL) method for the determination of rhein coupled with flow-injection
analysis (FIA) is developed. It is based on the strong sensitizing effect on the weak CL reaction between luminol and ferricyanide
in alkaline solution. Under optimal experimental conditions, the relative CL intensity is proportional to the concentration
of rhein in the range of 7.0 × 10−12–7.0 × 10−10 mol L−1 and 1.0 × 10−9–4.0 × 10−5 mol L−1, the detection limit is 1.478 × 10−13 mol L−1, and the relative standard deviation (RSD) for 9 parallel measurements of 1.408 × 10−7 mol L−1 rhein is 3.4%. The method was successfully applied to the determination of rhein in pharmaceutical preparations. The possible
mechanism of CL is also briefly discussed. 相似文献
5.
A 3-amino-5-mercapto-1,2,4-triazole (TA) self-assembled monolayer-modified gold electrode (TA SAM/Au) is characterized by
X-ray photoelectron spectroscopy, A.C. impedance, cyclic voltammetry, chronoamperometry and chronocoulometry. The TA SAM/Au
exhibited good promotion of the electrochemical oxidation of dopamine. Some electrochemical parameters of dopamine such as
electron transfer number, exchange current density, standard heterogeneous rate constant, diffusion coefficient, etc., were
measured by different electrochemical methods. The peak currents of dopamine were linearly dependent on its concentration
in the range of 1.5 × 10−6–1.0 × 10−4 mol L−1, with a detection limit of 5.0 × 10−7 mol L−1. The oxidative peak potentials of dopamine and ascorbic acid were well separated at about 190 ± 10 mV in pH 2.0 BR buffers
at TA SAM/Au, the oxidation peak current increases approximately linearly with increasing concentration of both dopamine and
ascorbic acid in the concentration range of 9.98 × 10−6–4.54 × 10−4 mol L−1. It can be used for simultaneous determination of dopamine and ascorbic acid. 相似文献
6.
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
7.
A sensitive adsorptive anodic stripping procedure for the determination of trace zirconium at a carbon paste electrode (CPE)
has been developed. The method is based on adsorptive accumulation of the Zr(IV)-alizarin red S(ARS) complex onto the surface
of the CPE, followed by oxidation of adsorbed species. The optimal experimental conditions include the use of 0.10 mol · L−1 ammonium acetate buffer (pH 4.3), ARS, an accumulation potential of 0.20 V (versus SCE), an accumulation time of 2 min, a
scan rate of 200 mV · s−1 and a second-order derivative linear scan mode. The oxidation peak for the complex appears at 0.69 V. The peak current is
proportional to the concentration of Zr(IV) over the range of 1.0 × 10−9–2.0 × 10−7 mol · L−1, and the detection limit is 3 × 10−10 mol · L−1 for a 2 min adsorption time. The relative standard deviations (n = 8) for 5.0 × 10−8 and 5.0 × 10−9 mol · L−1 Zr(IV) are 3.3 and 4.8%, respectively. The proposed method was applied to the determination of zirconium in ore samples with
satisfactory results. 相似文献
8.
A new chemiluminescence (CL) method combined with flow injection technique is described for the determination of Cr(III) and
total Cr. It is found that a strong CL signal is generated from the reaction of Cr(III), lucigenin and KIO4 in alkaline condition. The determination of total Cr is performed by pre-reduction of Cr(VI) to Cr(III) by using H2SO3. The CL intensity is linearly related to the concentration of Cr in the range 4.0 × 10−10–1.0 × 10−6 g mL−1. The detection limit (3s
b) is 1 × 10−10 g mL−1 Cr and the relative standard deviation is 1.9% (5.0 × 10−8 g mL−1 of Cr(III) solution, n = 11). The method was applied to the determination of Cr(III) and total Cr in water samples and compared satisfactorily with
the official method. 相似文献
9.
A novel L-cysteine film modified electrode has been fabricated by means of an electrochemical oxidation procedure, and it
was successfully applied to the electrochemical determination of acetaminophen. This method utilizes the electrooxidation
of amines to their analogous cation radicals to form a chemically stable covalent linkage between the nitrogen atom of the
amine and edge plane sites at the glassy carbon electrode surface. The electrochemical behaviour of acetaminophen at the film
electrode was investigated in 0.1 mol L−1 phosphate buffer (pH 6.20). It was found that the redox peak current of acetaminophen was enhanced greatly on the film electrode.
Linearity between the oxidation peak current and the acetaminophen concentration was obtained in the range of 1.0 × 10−4–2.0 × 10−7 mol L−1 with a detection limit of 5.0 × 10−8 mol L−1. For seven parallel detections of 1.0 × 10−5 mol L−1 acetaminophen, the relative standard deviation (RSD) was 1.46%, suggesting that the film electrode has excellent reproducibility.
Application to the determination of acetaminophen in drug tablets and human urine demonstrated that the film electrode has
good stability and high sensitivity. 相似文献
10.
Sayed S. Badawy Yousry M. Issa Waheed F. El-Hawary Manal S. Ashour 《Mikrochimica acta》2001,136(1-2):1-7
A PVC membrane electrode selective for cetyldimethylethylammonium (CDEA) ion was prepared. The active element is a plasticized
poly vinyl chloride membrane containing a dissolved ion associate complex of CDEA with phosphotungstic acid (PTA). The electrode
showed a near-Nernstian response within the CDEA+ concentration range 2.34 × 10−6 to 1.96 × 10−4 M at 25 ± 1^C, good selectivity, and is usable within the pH range 3.5–9.0. The isothermal temperature coefficient of the electrode amounted
to −0.00012 V/°C. The electrode has been used for the direct determination of cetyldimethylethylammonium bromide either by
the standard addition method or by potentiometric titration against PTA.
Received January 1, 1998. Revision June 13, 2000. 相似文献
11.
A novel procedure was developed for the determination of trace cerium on the basis of anodic adsorption voltammetry of the
Ce(III)–alizarin complexon (ALC) complex at a carbon paste electrode (CPE). The procedure is convenient to determine cerium
individually in the presence of other rare earths because there is a 100 mV difference between the peak potentials of Ce(III)–ALC
and other rare earth(III)–ALC complexes in a supporting electrolyte of 0.08 M HAc–NaAc and 0.012 M potassium biphthalate (pH
4.7) when performing linear-scanning from −0.2 to 0.8 V (vs. SCE) at 100 mV/s. The second-order derivative peak currents are directly proportional to the Ce(III) concentration over
a range of 6.0 × 10−9–3.0 × 10−7 M. The detection limit is as low as 2.0 × 10−9 M (S/N = 3) for a 120 s preconcentration. An RSD of 3.5% was obtained for 15 determinations of Ce(III) at a concentration of 4.0
× 10−8 M on the same CPE surface. The method was applied successfully to the determination of cerium in samples of rare earth nodular
graphite cast iron. 相似文献
12.
Hui Du Jianyu He Sicen Wang Langchong He 《Analytical and bioanalytical chemistry》2010,397(5):1947-1953
The dissociation equilibrium constant (K
D) is an important affinity parameter for studying drug–receptor interactions. A vascular smooth muscle (VSM) cell membrane
chromatography (CMC) method was developed for determination of the K
D values for calcium antagonist–L-type calcium channel (L-CC) interactions. VSM cells, by means of primary culture with rat
thoracic aortas, were used for preparation of the cell membrane stationary phase in the VSM/CMC model. All measurements were
performed with spectrophotometric detection (237 nm) at 37 °C. The K
D values obtained using frontal analysis were 3.36 × 10−6 M for nifedipine, 1.34 × 10−6 M for nimodipine, 6.83 × 10−7 M for nitrendipine, 1.23 × 10−7 M for nicardipine, 1.09 × 10−7 M for amlodipine, and 8.51 × 10−8 M for verapamil. This affinity rank order obtained from the VSM/CMC method had a strong positive correlation with that obtained
from radioligand binding assay. The location of the binding region was examined by displacement experiments using nitrendipine
as a mobile-phase additive. It was found that verapamil occupied a class of binding sites on L-CCs different from those occupied
by nitrendipine. In addition, nicardipine, amlodipine, and nitrendipine had direct competition at a single common binding
site. The studies showed that CMC can be applied to the investigation of drug–receptor interactions. 相似文献
13.
Andreas Rahm Evgeni M. Kaidashev Heidemarie Schmidt Mariana Diaconu Andreas Pöppl Rolf Böttcher Christoph Meinecke Tilman Butz Michael Lorenz Marius Grundmann 《Mikrochimica acta》2006,153(1-2):21-25
A flow injection chemiluminescence method is proposed for the determination of cobalt, based on the strong catalytic effect
of Cobalt(II) (1,10-phenanthroline)3 complex on the lucigenin-periodate reaction in alkaline medium. Under the optimum experimental conditions, the chemiluminescence
signal responded linearly to the concentration of cobalt(II) in the 1.0 × 10−9–3.0 × 10−7 g mL−1 range with a detection limit of 4.4 × 10−10 g mL−1 cobalt(II). The relative standard deviation for the determination of 5.0 × 10−8 g mL−1 of cobalt was 2.3% in eleven replicated measurements. The method was successfully applied to the determination of cobalt(II)
in pharmaceutical preparations. 相似文献
14.
Ali Z. Abu Zuhri Nidal A. Zatar Raqi M. Shubietah Hala H. Arafat 《Mikrochimica acta》2000,134(3-4):153-160
Two methods are described for quantitative determination of nizatidine. The first is a cathodic stripping voltammetric method
which is based on the accumulation of the compound at the hanging mercury drop electrode. The adsorptive stripping response
was evaluated with respect of accumulation time, potential, concentration, pH and other variables. A linear calibration graph
was obtained over the range 3.0×10−8–1.0×10−6 M with a detection limit 3.0×10−8 M after a 20s accumulation time at −0.2 V accumulation potential. On the other hand, it was found that the detection limit
could be lowered to 1.0×10−8 M after 180s accumulation time at −0.2 V accumulation potential. The relative standard deviation was in the range 1.2−2.0%
for six measurements. The tolerance amounts of the common excipients have also been reported.
The second is a spectrophotometric method which is based on the formation and extraction of the ion-pair complex formed between
nizatidine and either bromocresol green or bromothymol blue. The extracted colored ion-pair complexes absorb at 416 nm. The
effect of different factors such as: type of organic solvent, pH, reagent concentration, number of extraction times, shaking
time, temperature and the tolerance amount of the common excipients have been reported. The calibration graph was linear in
the range 6.0×10−7–1.8×10−5 M with a detection limit of 6.0×10−7 M and molar absorptivity of 2.1×104 lċmol−1ċcm−1 when using bromocresol green, while the calibration graph was linear in the range 3.0×10−7–1.1×10−5 M with a detection limit of 3.0×10−7 M and molar absorptivity of 3.2×104 lċmol−1ċcm−1 when using bromothymol blue. The spectrophotometric methods offer alternative methods with reasonable sensitivity, selectivity
and accuracy with relative standard deviation in the range 2.1−6.0% and 1.2−4.7% (for six measurements) when using bromothymol
blue and bromocresol green, respectively. The proposed two methods were applied for the determination of nizatidine in commercially
available dosage forms. A comparison between the voltammetric and the extraction-spectrophotometric methods was also reported.
Received April 19, 1999. Revision August 30, 1999. 相似文献
15.
M. Soledad García Joaquín Ortuño M. Isabel Albero María Cuartero 《Analytical and bioanalytical chemistry》2009,394(6):1563-1567
A trazodone-selective electrode for application in pharmaceutical quality control and urine analysis was developed. The electrode
is based on incorporation of a trazodone-tetraphenylborate ion exchanger in a poly(vinyl chloride) membrane. The electrode
showed a fast, stable and Nernstian response over a wide trazodone concentration range (5 × 10−5−1 × 10−2 M) with a mean slope of 59.3 ± 0.9 mV/dec of concentration, a mean detection limit of 1.8 × 10−5 ± 2.2 × 10−6 M, a wide working pH range (5–7.5) and a fast response time (less than 20 s). The electrode also showed good accuracy, repeatability,
reproducibility and selectivity with respect to some inorganic and organic compounds, including the main trazodone metabolite.
The electrode provided good analytical results in the determination of trazodone in pharmaceuticals and spiked urine samples;
no extraction steps were necessary. Dissolution testing of trazodone tablets, in different conditions of pH and particle size,
based on a direct potentiometric determination with the new selective electrode is presented as well. 相似文献
16.
Newly developed, simple, low-cost and sensitive ion-selective electrodes have been proposed for determination of some antiepileptic
drugs such as lamotrigine, felbamate, and primidone in their pharmaceutical preparations as well as in biological fluids.
The electrodes are based on poly(vinyl chloride) membranes doped with drug–tetraphenyl borate (TPB) or drug–phosphotungstic
acid (PT) ion-pair complexes as molecular recognition materials. The novel electrodes displayed rapid Nernstian responses
with detection limits of approximately 10−7 M. Calibration graphs were linear over the ranges 5.2 × 10−7–1.0 × 10−3, 1.5 × 10−6–1.0 × 10−3, and 2.6 × 10−7–1.0 × 10−3 M for drug–TPB and 5.8 × 10−7–1.0 × 10−3, 1.8 × 10−7–1.0 × 10−3, and 6.6 × 10−7–1.0 × 10−3 M for drug–PT electrodes, respectively, with slopes ranging from 52.3 to 62.3 mV/decade. The membranes developed have potential
stability for up to 1 month and proved to be highly selective for the drugs investigated over other ions and excipients. The
results show that the selectivity of the ion-selective electrodes is influenced significantly by the plasticizer. The proposed
electrodes were successfully applied in the determination of these drugs in pharmaceutical preparations in four batches of
different expiry dates. Statistical Student’s t test and F test showed insignificant systematic error between the ion-selective electrode methods developed and a standard method. Comparison
of the results obtained using the proposed electrodes with those found using a reference method showed that the ion-selective
electrode technique is sensitive, reliable, and can be used with very good accuracy and high percentage recovery without pretreatment
procedures of the samples to minimize interfering matrix effects.
Figure Structure of lamotrigine, felbanate and primidone 相似文献
17.
The electrooxidative behaviour and determination of quetiapine (QTP), a dibenzothiazepine derivative and antipsychotic agent,
on a glassy carbon disc electrode was investigated using cyclic (CV), linear sweep (LSV), differential pulse (DPV) and Osteryoung
square wave voltammetry (OSWV). Fully validated DP and SW voltammetric procedures are described for the determination of QTP.
QTP in pH 3.5 acetate buffer solution presents a well-defined anodic response, studied by the proposed methods. This main
response was due to the irreversible, diffusion-controlled, one-electron and one-proton oxidation of the aliphatic nitrogen
of the piperazine ring. Under optimal conditions, a detection limit of 4.0 × 10−8 mol L−1 for DPV and 1.33 × 10−7 mol L−1 for OSWV, and a linear calibration graph in the range from 4.0 × 10−6 to 2.0 × 10−4 mol L−1 were obtained for both methods. The procedure was successfully applied to the determination of the drug in tablets, human
serum and human urine with good recoveries. The detection limits were 6.20 × 10−7 mol L−1 and 5.92 × 10−7 mol L−1 in human serum and 1.44 × 10−7 mol L−1 and 1.31 × 10−6 mol L−1 in human urine, for the DPV and OSWV method, respectively. 相似文献
18.
Chunya Li 《Mikrochimica acta》2007,157(1-2):21-26
Multi-wall carbon nanotubes (MWNT) were dispersed into water in the presence of dicetyl phosphate (DCP), and MWNT-DCP composite
film coated glassy carbon electrodes (GCE) were constructed. The electrochemical properties of 2-chlorophenol at a bare GCE
and MWNT-DCP modified GCE were compared. It was found that MWNT-DCP modified GCEs significantly enhance the oxidation peak
current of 2-chlorophenol and lowers its oxidation overpotential, suggesting great potential in the sensitive determination
of 2-chlorophenol. Finally, a sensitive and simple voltammetric method was developed for the determination of 2-chlorophenol.
The oxidation peak current increases linearly with the concentration in the range of 1.0 × 10−7–2.0 × 10−5 mol L−1, and the detection limit is 4.0 × 10−8 mol L−1 for 2 min accumulation. The method was successfully used to determine 2-chlorophenol in waste water samples. 相似文献
19.
A rapid flow-injection method with chemiluminescence (CL) detection is described for the determination of glutathione (GSH).
The method is based on the CL reaction of luminol and hydrogen peroxide. GSH can greatly enhance the chemiluminescence intensity
in 0.1 mol/L borax–sodium hydroxide buffer solution (pH = 9.7). The maximum CL intensity was directly proportional to the
concentration of GSH in the range 3.0 × 10−7–2.0 × 10−5 mol/L, and the detection limit was 6.8 × 10−8 mol/L. The relative standard deviation was 3.4% for 5.0 × 10−6 mol/L of GSH (n = 11).
Received October 23, 2001; accepted June 18, 2002 相似文献
20.
Xia Wu Lei Li Jinghe Yang Yuebo Wang Shuna Sun Naixing Wang 《Mikrochimica acta》2003,141(3-4):165-168
Yttrium was determined by means of the resonance light scattering (RLS) technique. The characteristics of resonance light
scattering spectra of yttrium-1, 6-bi(1′-phenyl-3′-methyl-5′-pyrazolone-4′-) hexanedione (BPMPHD), the effective factors and
optimum conditions were studied. In the pH range of 5.0–6.1, yttrium-BPMPHD complex produces three characteristic peaks of
RLS at 365, 402 and 467 nm. The enhanced intensity of RLS is proportional to the concentration of yttrium in the range of
1.0×10−8 to 1.0×10−5 mol · L−1. The limit of detection is 5.9×10−9 mol · L−1. The method has been used for the determination of Y3+ in mixed rare earths.
Correspondence: Key Lab for Colloid and Interface Chemistry of Education Ministry, School of Chemistry and Chemical Engineering,
Shandong University, Jinan 250100, People’s Republic of China. e-mail: wux@sdu.edu.cn
Received July 3, 2002; accepted October 20, 2002 相似文献