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1.
A square wave voltammetric method with a static mercury drop electrode (SMDE) was developed for the quantitative determination of iron (III) in Zn-Fe alloy galvanic baths. Real alloy bath samples were analyzed by the standard addition method and recovery tests were carried out. 0.50 mol L-1 sodium citrate (pH 6.0) or 0.20 mol L-1 oxalic acid (pH 4.0) were applied as supporting electrolytes resulting in both cases in a peak potential of about -0.20 V vs. AgIAgCl (saturated KCl). The iron (III) concentration in the alloy bath was 9.0 x 10(-4) mol L-1. A good correlation (r = 0.9999) was achieved between the iron (III) concentration and the peak current in the electrolytes studied, with linear response ranges from 1.0 x 10(-6) to 1.2 x 10(-4) mol L-1. Interference levels for some metals such as copper (II), lead (II), chromium (III) and manganese (II) that can hinder the Zn-Fe alloy deposition were evaluated; only copper (II) interferes seriously. 相似文献
2.
Summary A capillary electrophoretic method for the determination of Cu(II) and Co(III) chelates with ethylenediamine in electroless
copper plating baths has been developed. The influence of carrier electrolyte parameters such as nature of counter-ion and
pH were studied and discussed. The optimised separations were carried out in a fused silica capillary (57 cm × 75 μm I.D.)
filled with an ethylenediamine sulfate electrolyte (20 mol L−1 ethylendiamine, pH7.0 with H2SO4; applied voltage, +25 kV) using direct UV detection at 214 nm. The detection limits for a signalto-noise ratio of 3 and 10s
hydrodynamic injection were 5×10−6 mol L−1 for Cu(II) and 1×10−6 mol L−1 for Co(III). The relative standard deviations of the peak areas for Cu(II) and Co(III) were found to be 1.5% and 2.4%, respectively,
with five consecutive injections of standard solution containing 5×10−5 mol L−1 of each metal ion. Application of the method to the speciation of Cu(II) and Co(III) complexes in copper plating bath samples
is also demonstrated. 相似文献
3.
A flow injection method for the sequential determination of iron(II) and iron(III) was developed. It is based on the differential
reaction kinetics of iron(II) and iron(III) with Tiron in a double-injection FI system. The proposed method employs the accelerating
action of copper(II) for the oxidation of iron(II) in the presence of Tiron. A linear calibration graph is obtained for iron
(II) and iron(III) in the concentration range 1.8 × 10–5– 1.8 × 10–4 mol/L; the throughput of samples is 30 injections/h.
Received: 22 October 1996 / Revised: 4 December 1996 / Accepted: 10 December 1996 相似文献
4.
Fang Yan Chuanmin Ruan Xiaohong Chen J. Deng Jilie Kong 《Fresenius' Journal of Analytical Chemistry》1999,363(1):83-87
An irreversible reduction peak of oxymyoglobin (MbO2) was observed on the bare glassy carbon electrode (GCE) in acetate buffer solution under atmospheric conditions. It is the
reduction of bonded oxygen in Mb, but not the heme Fe(III)/Fe(II) redox couple that underwent electrochemical reaction on
the electrode. The peak current achieved a maximum value in acetate buffer solution of pH 4.0. The peak potential was pH dependent,
suggesting that the proton was involved in the electrochemical reaction. Furthermore, the peak current was linearly related
to the concentration of myoglobin in the range of 2.5 × 10–8∼ 1.0 × 10–6 mol · L–1 with a detection limit of 5 × 10–9 mol · L–1.
Received: 20 March 1998 / Revised: 24 June 1998 / Accepted: 1 July 1998 相似文献
5.
A catalytic adsorptive stripping voltammetric method for the determination of copper(II) on a carbon paste electrode (PCE)
in an alizarin red S (ARS)-K2S2O8 system is proposed. In this method, copper(II) is effectively enriched by both the formation and adsorption of a copper(II)-ARS
complex on the PCE, and is determined by catalytic stripping voltammetry. The catalytic enhancement of the cathodic stripping
current of the Cu(II) in the complex results from a redox cycle consisting of electrochemical reduction of Cu(II) ion in the
complex and subsequent chemical oxidation of the Cu(II) reduction product by persulfate, which reduces the contamination of
the working electrode from Cu deposition and also improves analytical sensitivity. In Britton-Robinson buffer (pH 4.56±0.1)
containing 3.6×10−5 mol L−1 ARS and 1.6×10−3 mol L−1 K2S2O8, with 180 s of accumulation at −0.2 V, the second-order derivative peak current of the catalytic stripping wave was proportional
to the copper(II) concentration in the range of 8.0×10−10 to ∼3.0×10−8 mol L−1. The detection limit was 1.6×10−10 mol L−1. The proposed method was evaluated by analyzing copper in water and soil. 相似文献
6.
S. Pozdniakova R. Ragauskas A. Dikius A. Padarauskas 《Fresenius' Journal of Analytical Chemistry》1999,363(1):124-125
A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior
to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm
× 75 μm I.D.) filled with a borate buffer (50 mmol L–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved
is 2 × 10–6 mol L–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.
Received: 27 February 1998 / Revised: 28 April 1998 / Accepted: 20 May 1998 相似文献
7.
Covalent modification of glassy carbon electrodes with glycine for voltammetric separation of dopamine and ascorbic acid 总被引:1,自引:0,他引:1
Glycine was covalently grafted on to a glassy carbon electrode (GCE) by amine cation radical formation in electrooxidation
of the amino-containing compound. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry proved the immobilization
of glycine on the GCE. The modified electrode reduced the overpotentials of dopamine (DA) and ascorbic acid (AA) by approximately
0.15 V and 0.23 V, respectively, and resolved the overlapping voltammetric response of DA and AA into two well-defined voltammetric
peaks in cyclic voltammetry (CV) or differential pulse voltammetry (DPV), unlike the unmodified GCE; this can be used for
the simultaneous determination of these species in a mixture. The differential pulse peak current was linearly dependent on
DA and AA concentration in the range 5 × 10–6– 8 × 10–4 mol L–1 and 6 × 10–5– 4 × 10–3 mol L–1, with correlation coefficients of 0.996 and 0.994, respectively. The detection limits (3δ) for DA and AA were 1.8 × 10–6 mol L–1 and 2.1 × 10–5 mol L–1, respectively. The modified electrode is very sensitive, selective and stable, and has been applied to the determination
of DA and AA simultaneously in samples with satisfactory results.
Received: 30 October 2000 / Revised: 9 March 2001 / Accepted: 13 March 2001 相似文献
8.
A simple and fast flow injection fluorescence quenching method for the determination of iron in water has been developed.
Fluorimetric determination is based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An
emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The carrier solution used
was 2 × 10−6 mol L−1 salicylic acid in 0.1 mol L−1 NH4+/NH3 buffer solution at pH 8.5. Linear calibration was obtained for 5–100 μg L−1 iron(III) and the relative standard deviation was 1.25 % (n = 5) for a 20 μL injection volume iron(III). The limit of detection
was 0.3 μg L−1 and the sampling rate was 60 h−1. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully
applied to the determination of low levels of iron in real samples (river, sea, and spring waters). 相似文献
9.
S. Pozdniakova R. Ragauskas A. Dikčius A. Padarauskas 《Analytical and bioanalytical chemistry》1999,363(1):124-125
A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior
to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm
× 75 μm I.D.) filled with a borate buffer (50 mmol L–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved
is 2 × 10–6 mol L–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.
Received: 27 February 1998 / Revised: 28 April 1998 / Accepted: 20 May 1998 相似文献
10.
Spectrofluorometric determination of hesperidin by manual and flow-injection methods 总被引:1,自引:0,他引:1
T. Pérez-Ruíz C. Martínez-Lozano V. Tomás J. Fenoll 《Fresenius' Journal of Analytical Chemistry》1999,364(3):279-283
A reliable and highly sensitive method for the determination of hesperidin is described. It involves the formation of a highly
fluorescent complex between hesperidin and aluminium (III) in a micellar medium. There is a linear relationship between fluorescence
intensity (λem = 496 nm, λex = 391 nm) and hesperidin concentration over the range 5 × 10–7– 2 × 10–5 mol L–1. The detection limit is 79 μg L–1. The method can easily be adapted to a flow system using a three-channel manifold, the peak height being proportional to
the hesperidin concentration over the range 1 × 10–6– 1 × 10–4 mol L–1. Manual and flow-injection procedures have been successfully applied to the determination of hesperidin in orange peel and
orange juice.
Received: 21 October 1998 / Revised: 16 December 1998 / Accepted: 25 December 1998 相似文献
11.
Ying Chen Chang-Ming Ding Tian-Ze Zhou Da-Yong Qi 《Fresenius' Journal of Analytical Chemistry》1999,363(1):119-120
An organic solvent-soluble membrane filter (MF) is proposed for the simple and rapid reconcentration with subsequent spectrophotometric
determination of trace levels of iron (II) in water. Iron (II) is collected on a nitrocellulose membrane filter as ion associate
of an anionic complex, which is formed by iron (II) and Ferrozine and a cation-surfactant. The ion-pair compound and the MF
can be dissolved in small volumes of 2-ethoxyethanol and the absorbance of the resulting solution is measured at 560 nm against
a reagent blank with molar absorptivity of 4.01 × 104 L mol–1 cm–1. Beer’s law is obeyed over the concentration range 0–10 μg L–1 of iron (II) in water and the detection limit is 0.03 μg L–1 with a 50-fold enrichment factor. The proposed method can satisfactorily be applied to the determination of iron (II) in
natural water and sea water.
Received: 23 June 1998 / Revised: 21 July 1998 / Accepted: 25 August 1998 相似文献
12.
S. M. Sultan Aladdin M. Almuaibed A. Townshend 《Fresenius' Journal of Analytical Chemistry》1998,362(1):167-169
A new flow injection chemiluminescence method for the assay of medazepam is explored. The method involves the use of permanganate
in sulfuric acid for the oxidation of medazepam with the emission of chemiluminescence detected by a photomultiplier tube.
A simplex procedure was employed for optimising the conditions for high sensitivity detection, which were found to be 1.03
× 10–3 mol L–1 permanganate, 0.153 mol L–1 sulfuric acid and 3.43 mL min–1 flow rate. The linear calibration range was 3.7 × 10–5 to 1.7 × 10–3 mol L–1. The detection limit (3σ) and the sample throughput were 1.85 × 10–5 mol L–1 and 100 per hour, respectively. The relative standard deviation for 5 replicate determinations of 1.9 × 10–4 mol L–1 medazepam was 0.15%. Common excipients (starch, glucose, maltose, lactose) used in pharmaceutical preparations had no effect.
Received: 2 February 1998 / Revised: 20 May 1998 / Accepted: 25 May 1998 相似文献
13.
C. Sanchez-Pedreño M. S. García J. A. Ortuño M. I. Albero E. Ballester 《Analytical and bioanalytical chemistry》2001,369(7-8):680-683
A flow-through bulk optode based on the use of 1-(2-pyridylazo)-2-naphthol (PAN) immobilized in a plasticized poly(vinyl
chloride) membrane entrapped in a cellulose support, in conjuntion with the flow injection analysis technique, is proposed
for the determination of manganese(II). The calibration graph obtained at 570 nm was linear in the range 0.27–27.5 mg L–1 (5 × 10–6– 5 × 10–4 M) Mn(II) with a detection limit of 0.18 mg L–1. The coefficients of variation of the sensor response for 5.5 mg L–1 of Mn(II) were ±0.22% for consecutive measurements (n = 10), ±0.48% between days (n = 5) and ±0.38% between different membranes
(n = 6). The sensor was readily regenerated with the carrier acetic acid/acetate buffer of pH 4.5. The method was applied
to the determination of manganese in steels, waters and lemon tree leaves.
Received: 13 December 2000 / Revised: 25 January 2001 / Accepted: 26 January 2001 相似文献
14.
Dora Melucci Simona Montalbani Clinio Locatelli 《Central European Journal of Chemistry》2012,10(1):267-276
The present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol
L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and
copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems. 相似文献
15.
D. Dobnik M. Kolar J. Komljenovi Nj. Radi 《Fresenius' Journal of Analytical Chemistry》1999,365(4):314-319
The preparation of an ion-selective electrode by chemical treatment of copper wire and its application for the measurements
of copper (II) and iodide ions is described. The proposed reaction mechanism at the sensing surface, which explains the response
of the electrode to Cu2+ and iodide ions, is discussed. The prepared electrode was suitable for direct potentiometric measurements of iodide and copper
(II) in batch experiments down to concentrations of 1 × 10–5 mol L–1. A tubular electrode, prepared in the same way, may be used as a potentiometric sensor in a flow-injection analysis for Cu
(II) and/or iodide determinations.
Received: 4 December 1998 / Revised: 31 March 1999 / Accepted: 6 April 1999 相似文献
16.
Shengshui Hu Kangbing Wu Hongchao Yi Xuan Dai Dafu Cui 《Analytical and bioanalytical chemistry》2001,370(1):101-103
An 1-(pyridylazo)-2-naphthol modified glassy carbon electrode has been investigated as sensor for the measurement of trace
levels of Cd2+. Cd2+ is deposited on the surface of a PAN modified glassy carbon electrode at –1.10 V (vs. SCE) via forming Cd2+–PAN and subsequent reduction at the electrode. In the following step, Cd-PAN is oxidized, and voltammograms are recorded
by scanning the potential in a positive direction. Calibration plots were found to be linear in the range 2 × 10–8 mol/L to 8 × 10–7 mol/L. The detection limit was 5 × 10–10 mol/L, and the coefficient of variation, determined on one single electrode at a concentration of 5 × 10–7 mol/L, was calculated to be 3.2% (n = 5). Using this new kind of modified electrode, trace levels of Cd(II) in water samples
were determined; the average recovery was calculated to be 98.78%.
Received: 17 August 2000 / Revised: 19 December 2000 / Accepted: 27 December 2000 相似文献
17.
A new Schiff-base ligand [N, N′, N″-Tri- (2,4-dihydroxyacetophenone) – triaminotriethylamine (TDATA)] with a tripodal structure
was synthesized. Its fluorescence intensity with the europium(III) complex was increased about 178-fold in the presence of
sodium acetate (NaAc) and about 126-fold in the presence of sodium phosphate (Na3PO4) solution. After adding the organic solvent dimethylsulfoxide (DMSO) to the above system, which leads to Eu3+ the fluorescence was further enhanced about 12-fold. Spectrofluorimetric determination of trace amounts of Eu3+ based on the phenomenon was performed. The excitation and emission wavelength is 365 nm and 615 nm, respectively. Under optimum
conditions, the fluorescence intensities vary linearly with the concentration of Eu3+ in the range of 4.9 × 10−12–3.2 × 10−6 mol · L−1 with a detection limit of 4.5 × 10−12 mol · L−1 (for the TDATA-NaAc-DMSO system) or 6.2 × 10−11–8.6 × 10−6 mol · L−1 with a detection limit of 6.0 × 10−11 mol · L−1 (for the TDATA-Na3PO4-DMSO system). Interferences of some rare earth metals and other inorganic ions are described. The method is a selective,
sensitive, rapid and simple analytical procedure for the determination of europium(III) in a high purity yttrium oxide and
synthetic sample. The mechanism for the fluorescence enhancement is also discussed. 相似文献
18.
M. R. Ganjali Tahereh Poursaberi Fatemeh Basiripour Masoud Salavati-Niassari Mohammad Yousefi Mojtaba Shamsipur 《Analytical and bioanalytical chemistry》2001,370(8):1091-1095
A PVC membrane electrode based on a cadmium–salen (N,N′-bis-salicylidene-1,2ethylenediamine) complex as an anion carrier is described. The electrode has an anti-Hofmeister selectivity
sequence with a preference for thiocyanate at pH 1.5–11.0. It has a linear response to thiocyanate from 1.0 × 10–6 to 1.0 × 10–1 mol L–1 with a slope of 59.1 ± 0.2 mV per decade, and a detection limit of 7 × 10–7 mol L–1. This electrode has high selectivity for thiocyanate relative to many common organic and inorganic anions. The proposed sensor
has a fast response time of approximately 15 s. It was applied to the determination of thiocyanate in a milk sample.
Received: 1 December 2000 / Revised: 19 April 2001 / Accepted: 30 April 2001 相似文献
19.
Pyrene-tetramethylpiperidinyl (Pyr-Tempo) as a spin label fluorescent probe for iron(II) was synthesized. It exhibited weak
fluorescence (λexc/λem = 346/399 nm) in aqueous solution due to an intramolecular quenching pathway. A method for determination of iron(II) was
proposed based on the fluorescence enhancement of the probe in the presence of iron(II) in acidic medium. Under optimum conditions,
the fluorescence enhancement of Pyr-Tempo is linearly proportional to the iron(II) concentration range of 6.0 × 10−8 to 9.6 × 10−6 mol L−1 with a detection limit of 8.0 × 10−9 mol L−1. The relative standard deviation (RSD) of six replicate measurements is 1.95% for 3.0 × 10−7 mol L−1 iron(II). The developed spin label fluorescence probe is found to be rapidly and sensitively responsive to iron(II) with
high selectivity compared to existing fluorescence methods. The proposed method was successfully applied to iron(II) detection
in five real samples with satisfactory results obtained by manual UV/Vis spectrophotometry (standard method) with 1,10-phenanthroline. 相似文献
20.
The electrochemical behavior of the ofloxacin–copper complex, Cu(II)L2, at a mercury electrode, and the interaction of DNA with the complex have been investigated. The experiments indicate that
the electrode reaction of Cu(II)L2 is an irreversible surface electrochemical reaction and that the reactant is of adsorbed character. In the presence of DNA,
the formation of the electrochemically non-active complexes Cu(II)L2-DNA, results in the decrease of the peak current of Cu(II)L2. Based on the electrochemical behavior of the Cu(II)L2 with DNA, binding by electrostatic interaction is suggested and a new method for determining nucleic acid is proposed. Under
the optimum conditions, the decrease of the peak current is in proportional to the concentration of nucleic acids in the range
from 3 × 10−8 to 3 × 10−6 g · mL−1 for calf thymus DNA, from 1.6 × 10−8 to 9.0 × 10−7 g · mL−1 for fish sperm DNA, and from 3.3 × 10−8 to 5.5 × 10−7 g · mL−1 for yeast RNA. The detection limits are 3.3 × 10−9, 6.7 × 10−9 and 8.0 × 10−9 g · mL−1, respectively. The method exhibits good recovery and high sensitivity in synthetic samples and in real samples. 相似文献