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1.
《Analytical letters》2012,45(15):2851-2859
Abstract This paper describes a kinetic potentiometric method for the determination of thiols (RSH): l‐cysteine (cys), N‐acetyl‐l‐cysteine (NAC), l‐glutathione (glu), and d‐penicillamine (pen). The proposed method is based on the reaction of formation the sparingly soluble salts, RSAg, between RSH and Ag+ ions. During this reaction potential‐time curves were recorded by using an electrochemical cell with commercial iodide selective electrode. The rectilinear calibration graphs are obtained in the RSH concentration range from 1.0×10?5 to 1.0×10?3 M. The applicability of the proposed method was demonstrated by determination of chosen compounds in pharmaceutical dosage forms. 相似文献
2.
《Analytical letters》2012,45(18):3392-3404
Abstract Clomipramine, an important tricylic antidepressant drug with low redox activity, was effectively electrocatalyzed on poly‐aminobenzene sulfonic acid/Pt nano‐clusters modified glassy carbon electrode (i.e., poly‐ABSA/Pt/GCE) and generated a sensitive anodic peak at about 0.80 V in pH 8.1 PBS. ABSA was electropolymerized on the surface of GCE modified with Pt nano‐clusters. Pt nanoparticles provide a 3 D and conductive structure for the polymer immobilization. The resulting sensor exhibited a considerable enhancement in voltammetric response characteristics: extending the linear range and lowering the detection limit. The anodic peak current of clomipramine was linear with its concentration over two concentration intervals, viz., 1.0×10?7~4.0×10?6 M and 4.0×10?6~4.0×10?5 M, with the detection limit of 1.0×10?9 M (S/N=3). This method was successfully applied to the determination of clomipramine in drug tablets and proved to be reliable compared with UV. 相似文献
3.
《Electroanalysis》2004,16(17):1413-1418
The in‐site functionalization of 4‐aminothiophenol (4‐ATP) self‐assembled monolayer on gold electrode at physiological pH yields a redox active monolayer of 4′‐mercapto‐N‐phenylquinone diimine (MNPD). The functionalized electrode exhibits excellent electrocatalytic responses towards dopamine (DA) and ascorbic acid (AA), reducing the overpotentials by about 0.22 V and 0.34 V, respectively, with greatly enhanced current responses. Due to its different catalytic activities toward DA and AA, the modified electrode resolves the overlapping voltammetric responses of DA and AA into two well‐defined voltammetric peaks by differential pulse voltammetry (DPV), which can be used for the simultaneous determination of these species in a mixture. The catalytic peak current obtained from DPV was linearly related to DA and AA concentration in the ranges of 5.0×10?6?1.25×10?4 M and 8.0×10?6?1.3×10?4 M with correlation coefficient of 0.999 and 0.998, respectively. The detective limits (3σ) for DA and AA were found to be 1.2×10?6 M and 2.4×10?6 M, respectively. The modified electrode shows good sensitivity, selectivity and stability, and has been applied to the determination of DA and AA simultaneously in samples with satisfactory results. 相似文献
4.
A sensitive and selective electrochemical method for the determination of dopamine (DA) was developed using a 4‐(2‐Pyridylazo)‐Resorcinol (PAR) polymer film modified glassy carbon electrode (GCE). The PAR polymer film modified electrode shows excellent electrocatalytic activity toward the oxidation of DA in a phosphate buffer solution (PBS) (pH 4.0). The linear range of 5.0×10?6–3.0×10?5 M and detection limit of 2.0×10?7 M were observed. Simultaneous detection of AA, DA and UA has also been demonstrated on the modified electrode. This work provides a simple and easy approach to selective detection of DA in the presence of AA and UA. 相似文献
5.
《Analytical letters》2012,45(6):1075-1086
Abstract A novel plasticized membrane sensor for Ho(III) ions based on N‐(1‐thien‐2‐ylmethylene)‐1,3‐benzothiazol‐2‐amine (TBA) as a neutral carrier was prepared. The best performance was obtained with a membrane composition of 31% PVC, 61% benzyle acetate, 2% sodium tetra phenyl borate and 6% carrier. The electrode exhibits a Nernstian response for Ho(III) ions over a particular concentration range (1.0×10?5?1.0×10?2 M) with a slope of 19.7±0.2 mV decade?1. The limit of the detection is 7.0×10?6 M. The sensor has a response time of <15 s and a useful working pH range of 4.0–9.5. The proposed sensor discriminates relatively well towards Ho(III) ions with regard to common alkali, alkaline earth, and specially lanthanide ions. It was successfully applied as an indicator electrode in a potentiometric titration of Ho(III) ions with EDTA. It was also applied in determination of fluoride ions in a mouth wash preparation. The proposed sensor was applied for the determination of Ho(III) ion concentration in binary mixtures. 相似文献
6.
《Analytical letters》2012,45(1):151-162
Abstract A novel developed spectrofluorimetric method for the determination of trazodone hydrochloride in the presence of sodium dodecyl sulfate (SDS) surfactant micelles was described. Under optimal conditions, there was a good linear relationship between fluorescence intensity and trazodone hydrochloride concentration in the range of 4.0×10?9 to 8.0×10?6 mol · l?1with the detection limit of 1.3×10?9 mol · l?1 (S/N=3). This method has been used to determine trazodone hydrochloride in biological fluids. 相似文献
7.
《Analytical letters》2012,45(11):2001-2012
Abstract A simple, rapid, injection chemiluminescence method is described for the determination of prulifloxacin, a commonly used antibiotic. A strong chemiluminescence signal was detected when a mixture of the analyte and tris-(4,7-diphenyl-1,10-phenanthrolinedisulfonic acid)ruthenium(II) was injected into cerium(IV) sulfate. The chemiluminescence signal is proportional to the concentration of prulifloxacin in the range 4.0 × 10?8–9.0 × 10?6 mol L?1. The detection limit is 1.0 × 10?8 mol L?1, and the relative standard deviation is 2.2% (n = 11) for the determination of 8.0 × 10?7 mol L?1 prulifloxacin. The proposed method was successfully applied to the determination of prulifloxacin in pharmaceutical preparations in capsules, spiked serum, and urine samples. 相似文献
8.
《Analytical letters》2012,45(8):1596-1609
Abstract An original highly selective and sensitive PVC membrane sensor, working as a Fe(III) ion selective electrode and using 4‐amino‐6‐methyl‐3‐methylmercapto‐1,2,4‐triazin‐5‐one (AMMTO) as an ionophore, has been developed. This cetain sensor demonstrated the following performance; a linear dynamic range between 1.0×10?6 and 1.0×10?1 M with a near Nernstian slope of 19.4±0.5 mV per decade; a detection limit of 6.8×10?7 M; characteristically, the best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 65.5% nitrophenyl octyl ether, 2% sodium tetraphenyl borate and 2.5% AMMTO. Furthermore, the potentiometric response of the developed electrode is independent of the solution pH in the range of 2.2–4.8. The sensor possesses the advantages of short conditioning time, fast response time (<15 s) and, especially, great selectivity towards transition and heavy metal ions and some mono, di‐ and trivalent cations. The electrode can be used for at least 9 weeks without any considerable potential divergence. It was effectively used as an indicator electrode in the potentiometric titration of Fe(III) ions with EDTA and the direct determination of Fe3+ in different water samples. 相似文献
9.
《Analytical letters》2012,45(18):3405-3416
Abstract A post‐chemiluminescence (PCL) was observed when loperamide hydrochloride solution was injected into the reaction mixture after the finish of CL reaction of alkaline N‐Chlorosuccinimide (NCS) and dichlorofluorescein. Based on this phenomenon, a simple, sensitive and fast flow injection PCL method was established for the determination of loperamide hydrochloride. The possible mechanism for the PCL reaction was discussed via the investigation of the CL kinetic characteristics, the CL spectra, the fluorescence spectra. The PCL intensity responded linearly to the concentration of loperamide hydrochloride in the range 8.0×10?10 to 6.0×10?7 g · ml?1 with a linear correlation of 0.9995. The detection limit was 4×10?10 g · ml?1. The relative standard deviation was 2.4% for 4.0×10?8 g · ml?1 loperamide hydrochloride (n=11). This method has been applied to the determination of loperamide hydrochloride in human plasma and pharmaceutical samples with satisfactory results. 相似文献
10.
《Analytical letters》2012,45(12):2351-2359
Abstract Amperometric biosensors containing enzymes butyrylcholinesterase or acetylcholinesterase were prepared. The biosensors were employed for studying of cholinesterase reactivator: HI‐6. Competitions between HI‐6 and acetylthiocholine as enzyme substrate were used for determination of IC50 value. Biosensors with butyrylcholinesterase from human serum determined IC50 as (1.00±0.02)×10?6 M; the biosensor with acetylcholinesterase from human erythrocytes performance provided IC50 (3.31±0.13)×10?6 M, the one with human recombinant acetylcholinesterase (2.00±0.06)×10?6 M and finally biosensor with acetylcholinesterase from electric eel (6.17±0.17)×10?6 M when 5 mM acetylthiocholine as substrate was used. We are encouraged to consider presented biosensors as a very useful for evaluation of newly prepared cholinesterase reactivators. 相似文献
11.
《Analytical letters》2012,45(12):2317-2328
Abstract Rapid, simple, and accurate spectrophotometric method is presented for the determination of ibuprofen by batch and flow injection analysis methods. The method is based on ibuprofen competitive complexation reaction with phenolphthalein‐β‐cyclodextrin (PHP‐β‐CD) inclusion complex. The increase in the absorbance of the solution at 554 nm by the addition of ibuprofen was measured. Ibuprofen can be determined in the range 8.0×10?6 ?3.2×10?4 and 2.0×10?5?5.0×10?3 mol l?1 by batch and flow methods, respectively. The limit of detection and limit of quantification were 6.19×10?6 and 2.06×10?5 mol l?1 for batch and 1.77×10?5 and 5.92×10?5 mol l?1 for flow method, respectively. The sampling rate in flow injection analysis method was 120±5 samples h?1. The method was applied to the determination of pharmaceutical formulations. 相似文献
12.
In this paper, a silver doped poly(L ‐valine) (Ag‐PLV) modified glassy carbon electrode (GCE) was fabricated through electrochemical immobilization and was used to electrochemically detect uric acid (UA), dopamine (DA) and ascorbic acid (AA) by linear sweep voltammetry. In pH 4.0 PBS, at a scan rate of 100 mV/s, the modified electrode gave three separated oxidation peaks at 591 mV, 399 mV and 161 mV for UA, DA and AA, respectively. The peak potential differences were 238 mV and 192 mV. The electrochemical behaviors of them at the modified electrode were explored in detail with cyclic voltammetry. Under the optimum conditions, the linear ranges were 3.0×10?7 to 1.0×10?5 M for UA, 5.0×10?7 to 1.0×10?5 M for DA and 1.0×10?5 to 1.0×10?3 M for AA, respectively. The method was successfully applied for simultaneous determination of UA, DA and AA in human urine samples. 相似文献
13.
《Analytical letters》2012,45(18):3430-3442
Abstract The voltammetric determination of rutin in 0.04 mol l?1 B‐R buffer (pH 4.0) by square wave voltammograms (+0.41 V vs. Ag/AgCl(sat.)) at a poly glutamic acid modified glassy carbon electrode was found to be several orders of magnitude lower than that on a bare glassy carbon electrode. Rutin can be preconcentrated on the films of poly glutamic acid and presented linear relationship from concentration of 7×10?7 to 1×10?5 mol l?1 in 0.04 mol l?1 B‐R buffer pH 4.0. The method was successfully applied to the determination of rutin in pharmaceutical formulation without any pretreatment. 相似文献
14.
《Electroanalysis》2004,16(20):1734-1738
A novel biosensor by electrochemical codeposited Pt‐Fe(III) nanocomposites and DNA film was constructed and applied to the detection of uric acid (UA) in the presence of high concentration of ascorbic acid (AA). Based on its strong catalytic activity toward the oxidation of UA and AA, the modified electrode resolved the overlapping voltammetric response of UA and AA into two well‐defined peaks with a large anodic peak difference (ΔEpa) of about 380mV. The catalytic peak current obtained from differential pulse voltammetry (DPV) was linearly dependent on the UA concentration from 3.8×10?6 to 1.6×10?4 M (r=0.9967) with coexistence of 5.0×10?4 M AA. The detection limit was 1.8×10?6 M (S/N=3) and the presence of 20 times higher concentration of AA did not interfere with the determination. The modified electrode shows good sensitivity, selectivity and stability. 相似文献
15.
《Analytical letters》2012,45(17):3124-3137
Abstract A terbium-sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of prulifloxacin (PUFX). It was found that SDBS significantly enhanced the fluorescence intensity of the PUFX–Tb3+ complex (about 13-fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 290 nm and 545 nm, pH 8.0, 4.0 × 10?5 mol L?1 terbium(III), and 4.0 × 10?4 mol L?1 SDBS. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of PUFX over the range 6.0 × 10?8 to 2.0 × 10?6mol L?1 with a correlation coefficient of 0.9991. The detection limit (S/N = 3) was determined as 8.5 × 10?9 mol L?1. This method has been successfully applied for the determination of PUFX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range, and good stability. The luminescence mechanism of the system was also discussed in detail. In the fluorescence system of PUFX–Tb3+–SDBS, SDBS acted not only as the surfactant but also as the energy donor. 相似文献
16.
A microchip electrophoresis method with laser induced fluorescence detection was developed for the detection of agmatine (Agm) and octopamine (Oct). The fluorescent derivatization reagent, fluorescein isothiocyanate was used for precolumn derivatization of Agm and Oct. The sodium dodecyl sulfate (SDS) micelles was employed as pseudostationary phase for the separation of Agm and Oct with other endogenous compounds exist in biological samples. Some parameters including buffer concentration, buffer pH, SDS concentration and separation voltage were investigated in detail. Under the optimum conditions, the separation and determination of Agm and Oct was performed within 40 s. The calibration curves were linear for both Agm and Oct over the concentration range of 1.0 × 10?7 to 4.0 × 10?5 M and 1.5 × 10?7 to 4.5 × 10?5 M, respectively. The detection limits of Agm and Oct (S/N = 3) are 5.0 × 10?8 and 8.0 × 10?8 M, respectively. These values make the method very suitable for the determination of Agm and Oct in rat brain tissue and human plasma as demonstrated in this paper. 相似文献
17.
《Analytical letters》2012,45(5):973-983
Abstract A rapid and sensitive flow‐injection chemiluminescence (FI‐CL) method, which is based on the CL intensity that generated from the redox reaction of Ce(IV)‐rhodamine B in H2SO4 medium, for the determination of acyclovir and gancyclovir is described. For acyclovir, the determination range is 3×10?8 g mL?1–7×10?5 g mL?1, with 1.56×10?8 g mL?1 as its determination limit. During 11 repeated measurements for 1×10?6 g mL?1 acyclovir, the relative standard deviation was 2.08%. For gancyclovir, the determination range was 5×10?8 g mL?1–7×10?5 g mL?1, with 2.35×10?8 g mL?1 as its determination limit. The relative standard deviation is 2.83% with 11 repeated measurements of 1×10?6 g mL?1 gancyclovir. This method can be successfully used to determine the content of acyclovir and gancyclovir in injections, acyclovir in eye drops, and, maybe, also for other ciclovirs. 相似文献
18.
《Analytical letters》2012,45(4):689-704
Abstract The voltammetric behavior of dopamine was studied at a glassy carbon electrode modified by cysteic acid, based on electrochemical oxidation of L ‐cysteine. The modified electrode showed strong electrocatalytic activity towards dopamine and good selectivity. In a phosphate buffer solution (pH 7.4), the anodic peak current obtain from the differential pulse voltammetry of dopamine was linearly dependent on its concentration in the range of 5×10?9 to 4.0×10?6mol · L?1, with a detection limit of 2×10?9mol · L?1. The low‐cost modified electrode had been applied to the determination of dopamine in human serum and urine samples with satisfactory results. 相似文献
19.
《Electroanalysis》2002,14(24):1691-1698
Three different recently synthesized aza‐thioether crowns containing a 1,10‐phenanthroline sub‐unit (L1–L3) and a corresponding acyclic ligand (L4) were studied to characterize their abilities as silver ion ionophores in PVC‐membrane electrodes. Novel conventional silver‐selective electrodes with internal reference solution (CONISE) and coated graphite‐solid contact electrodes (SCISE) were prepared based on one of the 15‐membered crowns containing two donating S atoms and two phenanthroline‐N atoms (L1). The electrodes reveal a Nernstian behavior over wide Ag+ ion concentration ranges (1.0×10?5?1.0×10?1 M for CONISE and 5.0×10?8?4.0×10?2 M for SCISE) and very low limits of detection (8.0×10?6 M for CONISE and 3.0×10?8 M for SCISE). The potentiometric response is independent from pH of the solution in the pH range 3.0–8.0. The electrodes manifest advantages of low resistance, very fast response and, most importantly, good selectivities relative to a wide variety of other cations. The electrodes can be used for at least 2 months (for CONISE) and 4 months for (SCISE) without any appreciable divergence in potentials. The electrodes were used as an indicator electrode in the potentiometric titration of Ag+ ion and in the determination of silver in photographic emulsions and in radiographic and photographic films. 相似文献
20.
《Analytical letters》2012,45(12):1933-1941
Abstract A rapid and simple flow‐injection chemiluminescence (CL) method is described for the determination of perphenazine, which is based on the CL intensity that generated from the redox reaction of Ce (IV)-perphenazine in HNO3 medium is proportional to the perphenazine concentration without any sensitizers. The proposed method allows the determination range within 1.0×10?7–7.0 ×10?5 g mL?1 with a detection limit of 8.0×10?8 g mL?1, and it has been successfully applied to the determination of the perphenazine in pharmaceutical tablet compared well with the official method. 相似文献