共查询到20条相似文献,搜索用时 15 毫秒
1.
《Analytical letters》2012,45(6):1165-1173
Abstract The polarographic behavior of the complex of iron–4– (2–pyridylazo) resorcin(PAR) was studied. In HAc– NaAc– EDTA buffer solution, the complex can be adsorped on a hanging mercury drop electrode giving a sensitive adsorptive complex reduction peak with a peak potential at -0.36V(vs. SCE). Optimum experimental conditions were found by the use of 0.08mol/L HAc, 0.06mol/L NaAc, 5.0 × 10?3mol/L EDTA and 1.0 × 10?5mol/L PAR. With preconcentration for 60s, the derivative peak height of the complex compound is linearly proportional to the concentration for Fe in the range from 1.0 × 10?9mol/L to 1.0 × 10?7mol/L. For a 2–min pre–concentration time, the detection limit found was 2.0 × 10?10mol/L. This method has high sensitivity and selectivity. It has been applied to the determination of trace iron in food and water samples without any pre–separation step. 相似文献
2.
A simple and sensitive capillary electrophoretic method was developed for the separation and determination of sodium methyldithiocarbamate (metham), manganese ethylenebisdithiocarbamate (maneb) and ethyl xanthate in boric acid buffer by direct UV absorbance detection at λ = 254 nm. The separation is dependent on pH and nature of the buffer. The detection limits (S/N = 3) are 1.7 × 10–6 mol/L for ethyl xanthate, 1.3 × 10–6 mol/L for metham and 2.1 × 10–6 mol/L for maneb. The method has been successfully applied to the analysis of wheat samples spiked with maneb and in a commercial sample. 相似文献
3.
《Analytical letters》2012,45(15):2673-2682
Abstract A new heteronuclear complex, rare earth (III)-copper (II)-m-trifluomethyl chlorophosphonazo (CPA-mCF3) system for determining trace rare earth ions is presented. In a medium of 0.02mol/L NH4Cl,1. 0×10?3mol/L Cu(II),1.0×10?5 mol/L CPA-mCF3, a very sensitive polarographic adsorptive wave is observed by using a single sweep oscillopolarograph at about –0.83V (vs. Ag/AgCl). The linear relationship between the peak current and the concentration of rare earth exists from 6. 0×10?9 to 1. 0×10?6 mol/L. The detection limit of rare earth is down to 2. 0×10?9 mol/L for Tm3+. This method has been applied to determine trace RE in several samples of Chinese tea. The results are satisfactory. The composition of the complex is detected as RE (II): Cu (II): CPA-mCF3 = 1: 1: 2. 相似文献
4.
《Electroanalysis》2003,15(10):898-902
A method based on capillary electrophoresis (CE) with electrochemical detection (ED) was developed for the determination of taurine in Lycium Barbarum L., LIPOVIYAN beverage and milk powder. The effects of some important factors such as the acidity of the running buffer, separation voltage, injection time, and applied potential to working electrode were investigated. Operated in a wall‐jet configuration, a 300 μm diameter carbon‐disk electrode was used as the working electrode, which exhibits good responses at +1.05 V (vs. SCE) for taurine. Excellent linearity was obtained in the concentration range from 5.0×10?4 mol/L to 5.0×10?6 mol/L. The detection limit (S/N=3) was 1.0×10?7 mol/L. This proposed method has been successfully applied to analyze the actual samples with satisfactory assay results. 相似文献
5.
《Electroanalysis》2005,17(18):1675-1680
We developed a sensitive, simple and low cost method to determine methimazole based on capillary electrophoresis with electrochemical detection (CE‐EC) at a carbon fiber microdisk electrode (CFE). We investigated the effects of detection potential, the concentration and pH value of the phosphate buffer, and injection time as well as separation voltage on the detection of methimazole. Under the optimized conditions: the detection potential at 1.30 V, 10 mmol/L phosphate buffer (pH 7.0), injection time 30 s at a height of 20 centimeter and separation voltage at 15 kV, the linear range was obtained from 1.0×10?7 to 2.0×10?4 mol/L, covering 3 orders of magnitude with a correlation coefficient of 0.9995. The LOD (S/N=3) obtained was 5.0×10?8 mol/L. The RSD of migration time and peak current for 2.0×10?4 mol/L methimazole was 1.04% and 1.54% (n=10), respectively. The method was also used to analyze methimazole tablets and human urine sample. 相似文献
6.
《Analytical letters》2012,45(4):669-677
Abstract A new and convenient method for the rapid determination of aluminum in drinking waters using a.c. oscillopolarography in a lithium chloride system is described in this paper. The calibration graph is linear from 5 × 10?6 to 8 × 10?5 mol/L with a detection limit of 5 × 10?6 mol/L. The relative standard deviation of the method is 4.7% for 4 × 10?5 mol/L Al. Compared with other techniques, this method has the significant advantages of simple instrumentation, no deaeration procedure required and rapid measurement. It was particularly suitable to the analysis of 10?6 ~ 10?5 mol/L levels of Al in drinking waters. 相似文献
7.
《Electroanalysis》2002,14(23):1674-1678
Capillary zone electrophoresis with catalysis‐electrochemical detection has been developed and applied to determining horseradish peroxidase (HRP) at zeptomole levels. In this method, an on‐line enzyme catalysis reactor with a reaction capillary was designed. Isoenzymes of HRP were separated by capillary zone electrophoresis, and then they catalyzed the enzyme substrate 3,3′,5,5′‐tetramethylbenzide (TMB(Red)) and H2O2 in the reaction capillary. The reaction product, TMB(Ox), could be determined using amperometric detection on a carbon fiber microdisk bundle electrode at the outlet of the reaction capillary. Because of enzyme amplification, a significant amount of TMB(Ox) could be produced for detection. Therefore, the limit of detection (LOD) of HRP is very low. The optimum conditions of the method are 1.5×10?2 mol/L borate (pH 7.4) for the run buffer, 2×10?3 mol/L for the concentration of H2O2, 2×10?4 mol/L TMB(Red)+2.0×10?2 mol/L citrate‐phosphate (pH 5.0) for the substrate solution, 40 cm for the liquid pressure height, 20 kV for the separation voltage, 100 mV for the detection potential. HRP could be measured with a detection limit of 4.8×10?12 mol/L or 47.5 zmol (S/N=3). The linear range is from 2.40×10?11 to 2.40×10?8 mol/L. Using this method, commercial HRP was measured at zeptomole within ten minutes. 相似文献
8.
Hui Meng Fengwu Wu Zhike He Liangjie Yuan Qingyao Luo Yune Zeng 《International journal of environmental analytical chemistry》2013,93(3):299-307
Abstract The emission produced by sulfite after oxidation by potassium permanganate in acidic solution in the presence of Ru(phen)3 2+ is used to determine 1.0 × 10?7 to 2.5 × 10?5 mol/L sulfite. The limit of detection is 4.5 × 10?9 mol/L and the relative standard deviation is 3.1% for a 1 × 10?5 mol/L sulfite solution (n=8). The method was also applied satisfactorily to the determination of sulfur dioxide in air by using triethanolamine (TEA) as absorbent material. 相似文献
9.
Determination of furanic aldehydes in sugarcane bagasse by high‐performance liquid chromatography with pulsed amperometric detection using a modified electrode with nickel nanoparticles
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José Luiz da Silva Maísa Azevedo Beluomini Nelson Ramos Stradiotto 《Journal of separation science》2015,38(18):3176-3182
A glassy carbon electrode chemically modified with nickel nanoparticles coupled with reversed‐phase chromatography with pulsed amperometric detection was used for the quantitative analysis of furanic aldehydes in a real sample of sugarcane bagasse hydrolysate. Chromatographic separation was carried out in isocratic conditions (acetonitrile/water, 1:9) with a flow rate of 1.0 mL/min, a detection potential of – 50 mV vs. Pd, and the process was completed within 4 min. The analytical curves presented limits of detection of 4.0 × 10?7 mol/L and 4.3 × 10?7 mol/L, limits of quantification of 1.3 × 10?6 and 1.4 × 10?6 mol/L, amperometric sensitivities of 2.2 × 106 nA mol/L and 2.7 × 106 nA mol/L for furfural and 5‐hydroxymethylfurfural, respectively. The values obtained in this sample by the standard addition method were 1.54 ± 0.02 g/kg for 5‐hydroxymethylfurfural and 11.5 ± 0.2 g/kg for furfural. The results demonstrate that this new proposed method can be used for the quick detection of furanic aldehydes without the interference of other electroactive species, besides having other remarkable merits that include excellent peak resolution, analytical repeatability, sensitivity, and accuracy. 相似文献
10.
《Analytical letters》2012,45(9):1741-1753
Abstract An electroanalytical methood, based on derivative chronopotentiometry of the complex of beryllium(II) with 4-[(4-diethylamino-2-hydroxy-phenyl)-azo]-5-hydroxy-naphthalene-2,7-disurphonic acid (Beryllon II) accumulated adsorptively on the surface of a hanging mercury drop electrode, has been developed for determining trace beryllium in food. The dependences of the peak height on the dt/dE vs. E curve on the pre-concentration time, preconcentration potential and the constant reducing current are discussed. In 0.15 mol/1 NHs+0.05 mol/1 NH4Cl, 4×10?7 mol/l Beryllon II, and at a preconcentration potential of -0.30 V (ve. SCE), the limit of detection and linear range are 1 × l0?10 mol/l and 3 × 10?10 -2 × l0?7 mol/l, Iwpectively. The relative standard error of the method is 2.3% for 6 × 10?8 mol/l Be(II). The method WBB applied to samples of food. The electrode procees hae been diecueeed. 相似文献
11.
《Analytical letters》2012,45(15):3239-3252
ABSTRACT Potential dependent inhibition and enhancement effects of gallic acid on the electrochemiluminescence (ECL) of luminol in alkaline solutions were found. On the basis of the enhancement effect, a flow injection method was developed for the determination of gallic acid. The method was simple, convenient and sensitive. A detection limit of 1.8×10?8 mol/L, linear range of 3.0×10?8 - 1.0×10?4 mol/L, relative standard deviation of 1.0% for eleven measurements of 5.0×10?6 mol/L of gallic acid was found. This method was successfully applied to determine the content of gallic acid in Chinese gall (moshizi). 相似文献
12.
Irena Grabec Švegl Mitja Kolar Božidar Ogorevc Boris Pihlar 《Analytical and bioanalytical chemistry》1998,361(4):358-362
A vermiculite modified carbon paste electrode (VMCPE) was employed for the in situ preconcentration of traces of Hg(II) and Ag(I) via an ion-exchange route. Heavy metal ions were accumulated in Britton-Robinson (BR) buffer pH 7 for Hg(II) and pH 6 for Ag(I), and afterwards reduced at –0.7 V vs. Ag/AgCl in the separate measurement solution (BR buffer pH 5 + 0.05 mol/L NaNO3) prior to the anodic stripping square-wave voltammetric (ASSWV) detection. For Hg(II) ions, at 15 min accumulation, a linear range from 1.0 × 10–7 to 8.0 × 10–6 mol/L was obtained, with a 5.7 × 10–8 mol/L limit of detection. The VMCPE response was linear for Ag(I) ions in the concentration range from 2.0 × 10–7 to 8.0 × 10–6 mol/L, at 10 min accumulation with a corresponding limit of detection of 6.3 × 10–8 mol/L. The relative standard deviation of the analytical procedure including accumulation from a 5 × 10–7 mol/L solution of Hg (15 min) or Ag(I) (10 min), electrolysis, ASSWV detection, regeneration and activation of the VMCPE, was 4% (n = 6). The optimisation of the parameters for the application of the VMCPE in combination with ASSWV detection is presented and discussed. 相似文献
13.
《Analytical letters》2012,45(11):2259-2269
ABSTRACT A new method for the determination of ethanol is proposed based on the catalytic current of sulfate radical anion SO4 ?. In 0.1 mol/L KH2PO4–Na2HPO4 buffer (pH5.6±0.1)–1.6×10?2 mol/L K2S2O8 solution, the first order derivative peak current is proportional to ethanol concentration in the range of 1×10?4~9×10?4 (r = 0.9998). The limit of detection is 6×10?5 mol/L. The proposed method is applied to determine ethanol directly content in ardent spirits. The fundamental principle of the proposed method is that ethanol is oxidized by sulfate radical anion SO4 ? electrogenerated on the electrode surface to ethanol α-radical, and the reduction of the ethanol α-radical produces a polarographic reduction wave. 相似文献
14.
Hemoglobin was entrapped in composite electrodeposited chitosan‐multiwall carbon nanotubes (MCNTs) film by assembling gold nanoparticles and hemoglobin step by step. In phosphate buffer solution (pH 7), a pair of well‐defined and quasireversible redox peaks appeared with formal potential at ?0.289 V and peak separation of 100 mV. The redox peaks respected for the direct electrochemistry of hemoglobin at the surface of chitosan‐MCNTs‐gold nanoparticles modified electrode. The parameters of experiments have also been optimized. The composite electrode showed excellent electrocatalysis to peroxide hydrogen and oxygen, the peak current was linearly proportional to H2O2 concentration in the range from 1×10?6 mol/L to 4.7×10?4 mol/L with a detection limit of 5.0×10?7 mol/L, and this biosensor exhibited high stability, good reproducibility and better selectivity. The biosensor showed a Michaelis–Menten kinetic response as H2O2 concentration is larger than 5.0×10?4 mol/L, the apparent Michaelis–Menten constant for hydrogen peroxide was calculated to be 1.61 μmol/L. 相似文献
15.
《Analytical letters》2012,45(1):176-185
A poly(methyl red) film-modified glassy carbon electrode was fabricated and the oxidation behavior of tryptophan at the modified electrode was investigated by cyclic and linear sweep voltammetry. The oxidation peak current of tryptophan at the modified electrode increased significantly, and the oxidation process was irreversible and adsorption-controlled. An analytical method was developed for the determination of tryptophan in a phosphate buffer solution at pH 3.5. The anodic peak current varied linearly with a tryptophan concentration in the range 1.0 × 10?7 to 1.0 × 10?4 mol/L with a limit of detection of 4.0 × 10?8 mol/L. The proposed method was successfully applied to determine tryptophan in composite amino acid injections. 相似文献
16.
A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)‐gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)‐EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO4 (pH1.6), 6.0×10?3 mol/L GA, 3.0×10?3 mol/L V(IV), 4.0×10?3 mol/L EDTA, an accumulation potential of ?0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0×10?11 to 1.0×10?8 mol/L and the detection limit is 2×10?11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0×10?10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results. 相似文献
17.
A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection, has been developed for the determination of idarubicin in human urine. A carbon disk electrode was used as working electrode. The optimal conditions of separation and detection were pH 5.6 phosphate buffer ¶(0.20 mol/L), 22 kV for the separation voltage and 1.00 V (vs. Ag/AgCl, 3 mol/L KCl) for the detection potential. The linear range was from 4.0 × 10–7 to 2.0 × 10–5 mol/L with a regression coefficient of 0.9986, and the detection limit was 8.0 × 10–8 mol/L. The method was directly applied to the determination of idarubicin in spiked human urine without any other sample pretreatment except filtration, and the assay results were satisfactory. 相似文献
18.
《Electroanalysis》2006,18(3):291-297
Selected from a series of structurally related heteroaromatic thiols, a newly synthesized reagent 2‐amino‐5‐mercapto‐[1,3,4] triazole (MATZ) was used to fabricate self‐assembled monolayers (SAMs) on gold electrode for the first time. The MATZ/Au SAMs was characterized by electrochemical methods and scanning electronic microscopy (SEM). In 0.04 mol/L Britton–Robinson buffer solution (pH 5), the electrochemical behavior of dopamine showed a quasireversible process at the MATZ/Au SAMs with an electrode kinetic constant 0.1049 cm/s. However, the electrochemical reaction of uric acid at the SAMs electrode showed an irreversible oxidation process, the charge‐transfer kinetics of uric acid was promoted by the SAMs. By Osteryoung square‐wave voltammetry (OSWV), the simultaneous determination of dopamine and uric acid can be accomplished with an oxidation peak separation of 0.24 V, the peak current of dopamine and uric acid were linearly to its concentration in the range of 2.5×10?6–5.0×10?4 mol/L for dopamine and 1×10?6–1×10?4 mol/L for uric acid with a detection limit of 8.0×10?7 mol/L for dopamine and 7.0×10?7 mol/L for uric acid. The MATZ/Au SAMs electrode was used to detect the content of uric acid in real urine and serum sample with satisfactory results. 相似文献
19.
《Analytical letters》2012,45(15):2861-2875
Abstract A method based on capillary electrophoresis with electrochemical detection (CE‐ED) has been developed for the first time for the separation and determination of isovanillic acid, vanillic acid, quercetin, rosmarinic acid, caffeic acid, and protocatechuic acid in Origanum vulgare L. and its medicinal preparations. The effects of working electrode potential, pH level, concentration of running buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the analytes could be separated in a 50 mmol L?1 borate buffer (pH 8.7) within 21 min. A 300‐µm diameter carbon disk electrode has a good response at +0.95 V (vs. SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 4×10?8 g mL?1 to 2×10?7 g mL?1 for the analytes. The method has been successfully applied to the analysis of real sample, with satisfactory results. 相似文献
20.
《Analytical letters》2012,45(14):2345-2354
Abstract In Tris‐HCl buffer (pH=7.43), Tb3+ can react with oxolinic acid (OA) and form a 1:2 complex, which emits the intrinsic fluorescence of Tb3+. Based on this, a new fluorimetric method of determination of OA is developed. Under the optimum conditions, the enhanced fluorescence intensity of the system is proportional to the concentration of OA in the range of 1.5×10?7~2.5×10?5mol/L, and the detection limit is 5.5×10?9 mol/L. Recovery test was also satisfactory. The experiments indicated that the luminescence mechanism was attributed to the M*–M luminescence. 相似文献