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1.
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
2.
Paraskevas D. Tzanavaras Demetrius G. Themelis Anastasios Economou Georgios Theodoridis 《Mikrochimica acta》2003,142(1-2):55-62
Two new simple and rapid methods are reported for the accurate and precise spectrophotometric determination of captopril
(CPL) using flow (FI) and sequential injection (SI) analysis. The methods are based on the fast oxidation of CPL by Fe(III).
The produced Fe(II) reacts with 2,2′-dipyridyl-2-pyridylhydrazone (DPPH) in acidic medium to form a colored complex which
is monitored spectrophotometrically at 535 nm. Both methods allow the determination of the analyte up to 1000 mg L−1 at a sampling rate of 120 and 60 injections per hour for FI and SI, respectively. The methods are very precise [s
r=0.8 and 1.2% at 500 mg L−1 CPL (n=12) for FI and SI, respectively] and the 3σ detection limits (c
L=4.0 and 7.0 mg L1, respectively) are quite satisfactory. Their application to a variety of anti-hypertensive commercial pharmaceutical formulations
showed excellent results (relative errors, e
r, < ± 1.6% in all cases compared to an official HPLC method), while common pharmaceutical excipients were found not to interfere.
Recovery experiments further verified the accuracy of the developed methods, as the percent recoveries were in the range of
98.1–102.5%.
Author for correspondence. E-mail: themelis@chem.auth.gr
Received May 9, 2002; accepted January 8, 2003
Published online May 5, 2003 相似文献
3.
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
4.
An anodic stripping voltammetric procedure for the determination of Cu(II) at an in situ-plated stannum film electrode (SnFE)
was described. The results indicated that the SnFE had an attractive electroanalytical performance, with two distinct voltammetric
stripping signals for copper and stannum, and showed the superior advantage for the determination of copper compared with
the bismuth film electrode. Several experimental parameters were optimized. The SnFE exhibited highly linear behavior in the
concentration range from 1.0 to 100.0 μg L−1 of Cu(II) (r = 0.994) with the detection limit of 0.61 μg L−1 (S/N = 3), and the relative standard deviation for a solution containing 40.0 μg L−1 Cu(II) was 2.2% (n = 8). The procedure has been successfully applied for the determination of Cu(II) in lake water sample. 相似文献
5.
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
6.
Design of a field flow system for the on-line spectrophotometric determination of phosphate, nitrite and nitrate in natural water and wastewater 总被引:1,自引:0,他引:1
Ioannis A. Tsoulfanidis George Z. Tsogas Dimosthenis L. Giokas Athanasios G. Vlessidis 《Mikrochimica acta》2008,160(4):461-469
This study describes the design and optimisation of a field flow system for the in-situ collection and on-line determination
of phosphate, nitrate and nitrite by flow injection analysis-spectrophotometry. The method is based on the initial determination
of phosphate as its phosphoantimonylmolybdenum blue complex which is then oxidized on-line by nitrite and the decrease in
absorbance is monitored at 880 nm. Nitrate is determined as the difference between total and initial nitrite content in a
separate flow after reduction to nitrite in a cadmium reductive column. The calibration curves were linear in the range 0–2.00 mg L−1 P-phosphate, 0–10.00 mg L−1 nitrite and 0–7.00 mg L−1 nitrate with correlation coefficients of 0.9979, 0.9993 and 0.9995, respectively. The detection limits, calculated as 3S/N,
were 0.15 mg L−1 for P-phosphate, 0.17 mg L−1 for nitrite and 0.09 mg L−1 for nitrate. The reproducibility was below 3.0% (n = 7). Method validation in the analysis of natural water and wastewater samples revealed that it can efficiently be applied
to the determination of the target analytes, with recoveries in the range of 92–108%.
Correspondence: Athanasios G. Vlessidis, Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina,
Ioannina 45110, Greece 相似文献
7.
Ilona Šperlingová Ludmila Dabrowská Vladimír Stránský Šárka Dušková Jan Kučera Monika Tvrdíková Milon Tichy 《Analytical and bioanalytical chemistry》2010,397(2):433-438
Ethylene glycol monobutyl ether (EGBE), an industrial solvent, is absorbed by the body not only by inhalation but also by
dermal absorption (liquid or vapour). EGBE is metabolized to butoxyacetic acid (BAA). Pooled freeze-dried urine candidate
reference material (RM) was prepared from urine obtained from persons occupationally exposed to EGBE. This material has the
advantage of containing butoxyacetic acid in both the free and conjugated (glutamine and glycine) forms, as found in native
urine. In all GC method modifications used, acid hydrolysis was used to release BAA from its conjugated form. The amount of
butoxyacetic acid in homogeneity and stability testing was measured by GC after derivatisation with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide. Detection was by MS in EI mode, in the authors’ laboratory. For interlaboratory comparison of the
reference material GC methods with MS, FID, and ECD were used. Different extraction solvents (dichloromethane–isopropanol
2:1, ethyl acetate, or dichloromethane) and derivatisation reagents (trimethylsilyldiazomethane, N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide) were used. Using ANOVA (at the statistical level α = 0.05) no changes were found in the concentration of butoxyacetic acid during fifteen month isochronous stability testing,
or in homogeneity testing. The uncertainty contributions were u
h = 8.8 mg L−1 and u
s = 6.5 mg L−1. The concentration of butoxyacetic acid in freeze-dried urine RM was evaluated from the results of eight laboratory data
sets within an interlaboratory comparison by use of the interactive statistical software IPECA. The contribution to total
uncertainty derived from interlaboratory comparison was u
i = 12.7 mg L−1. The reference value (c = 273 ± 33 mg L−1) is an unweighted arithmetic average of accepted results. The value is traceable to the pure butoxyacetic acid (98% w/w; Acros Organic #257760010) used as calibrant. The uncertainty given is combined expanded uncertainty derived from the results
from interlaboratory comparison, and from homogeneity and stability tests (k = 2). The reference material will be used to verify method performance in the biological monitoring of occupational exposure
to EGBE. 相似文献
8.
Jeff E. Prest Sara J. Baldock Peter R. Fielden Nicholas J. Goddard Bernard J. Treves Brown 《Mikrochimica acta》2005,151(3-4):223-230
A new method allowing the simultaneous determination of arsenic(V), selenium(IV) and selenium(VI) using miniaturised isotachophoresis
has been developed. The method uses 0.02 M nitric acid buffered to pH 5.5 with histidine as the leading electrolyte. Using
a miniaturised poly(methyl methacrylate) chip device with an integrated conductivity detector, separations of model samples
and an industrial process stream sample were achieved. Limits of detection were calculated to be 0.85 mg L−1 for arsenic(V), 0.95 mg L−1 for selenium(IV) and 1.0 mg L−1 for selenium(VI). A method for the analysis of arsenic(III), using a glycolic acid based leading electrolyte to eliminate
carbonate interference is also presented. 相似文献
9.
D. A. Kostić G. Ž. Miletić S. S. Mitić I. D. Rašić V. V. Živanović 《Chemical Papers》2007,61(2):73-76
The complexation process of the transition metal Cu(II) with quercetin was studied. The investigation was conducted spectrophotometrically
in ethanol at the maximum absorption wavelength of 458.5 nm. Cu(II)—quercetin complex composition (1: 1) was determined using
the Job, Harvey—Manning, and mole ratio methods. Complex stability constant was calculated by the Job and mole ratio methods
and the respective logarithm values were 7.53 ± 0.25 and 7.44 ± 0.03. A new method for quantitative determination of the quercetin
content in solution was developed in this work. At the optimal conditions quercetin was determined in concentrations ranging
from 0.202 to 1.006 μg cm−3 with relative standard error of 2.5 % to 5.5 %. The lower detection limit was 0.067 μg cm−3. The method was found very accurate, reproducible, and sensitive, capable to determine microamounts of quercetin in pharmaceutical
preparations. 相似文献
10.
2,5-Dimercapto-1,3,4-thiadiazole (DMTD) self-assembled monolayer on gold electrode was prepared and investigated by electrochemical
measurement. The DMTD/Au electrode exhibited a significantly increased sensitivity and selectivity for Pb(II) in acetate buffer
(pH 5.5) at a potential of −1.0 V (vs Ag/AgCl) for 4 min by anodic stripping voltammetry. The influence of various experimental
parameters on the voltammetric response was studied. Under the optimized working conditions, the dependence of the stripping
peak current response on concentration of Pb(II) was linear in the range of 1–45 μmol L−1 with a correlation coefficient of 0.9988, and the detection limit was 0.10 μmol L−1. The relative standard deviation of the results was 3.4% for six successive determinations of a 20 μmol L−1 Pb(II) solution. A study of interfering substances was also performed. The method was applied to the determination of Pb(II)
in water samples with satisfactory results.
Correspondence: Hong Qun Luo, School of Chemistry and Chemical Engineering, Southwest University, 400715 Chongqing, China 相似文献
11.
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
12.
Leonardo Sena Gomes Teixeira Antônio Celso Spínola Costa Júlio César Rosa Assis Sérgio Luis Costa Ferreira Mauro Korn 《Mikrochimica acta》2001,137(1-2):29-33
A new sensitive method exploiting solid-phase spectrophotometry is proposed for the determination of cobalt in pharmaceutical
preparations. The chromogenic reagent 1-(2-thiazolylazo)-2-naphthol (TAN) was immobilized on C18 bonded silica loaded into
a home-made cell with 1.5 mm of optical path for cobalt determination. Cobalt(II) reacts with TAN on C18 material, at pH 6.0–7.5,
to give a coloured complex which has maximum absorption at 572 nm. In this way, the sample was passed through the cell and
Co(II) ions were quantitatively retained on the solid-phase. After the direct measurement of light-absorption in the solid
phase, only the cobalt was eluted with 0.1 mol L−1 hydrochloric acid. The cell was washed with water and then another sample solution could be passed through the cell. The
procedure allowed the determination of cobalt in the range of 10–160 μg L−1 with coefficient of variation of 4.7% (n=10) and apparent molar absorptivity of 2.62 × 106 L mol−1 cm−1 using sample volume of 3-mL.
Received May 15, 2000. Revision August 28, 2000. 相似文献
13.
Gongjun Yang Xilong Qu Ming Shen Chengyin Wang Qishu Qu Xiaoya Hu 《Mikrochimica acta》2008,160(1-2):275-281
Poly(phenol red) (denoted as PPR) films were electrochemically synthesized on the surface of a glassy carbon electrode (GCE)
by cyclic voltammetry to obtain a chemically modified electrode (denoted as PPR-GCE). The growth mechanism of PPR films was
studied by attenuated total reflection spectroscopy. This PPR-GCE was used to develop a novel and reliable method for the
determination of trace Pb2+ by anodic stripping differential pulse voltammetry. At optimum conditions, the anodic peak exhibits a good linear concentration
dependence in the range from 5.0 × 10−9 to 5.0 × 10−7 mol L−1 (r = 0.9989). The detection limit is 2.0 × 10−9 mol L−1 (S/N = 3). The method was employed to determine trace levels of Pb2+ in industrial waste water samples.
Correspondence: Gongjun Yang, Ming Shen, College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002,
P.R. China 相似文献
14.
Citric acid was thermochemically esterified onto defatted cotton fibre to produce a carboxyl cotton chelator (CCC), which
had been used for extraction of copper prior to its determination by flame atomic absorption spectrometry. The extraction
of copper has been studied under both batch and column methods. Quantitative extraction of copper was achieved in the pH range
4–7. The time needed to extract each sample was less than 30 min by the batch method. The copper extraction capacity of CCC
was found to be 22.7 mg g−1 at optimal pH value. The elution was quantitative with 1 mol L−1 hydrochloric acid. The feasible flow rate of copper-containing solution for quantitative extraction onto the column packed
with CCC was 0.5–4.0 mL min−1, whereas for elution it was less than 1.5 mL min−1. A 100-fold extraction factor could be achieved under the optimal column conditions. The tolerance limits for common metal
ions on the extraction of copper and the time of column reuse were investigated. The proposed method has been successfully
applied for extraction and determination of copper in industrial wastewater and natural water samples. 相似文献
15.
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
16.
Jorge L. Guzmán Mar Leticia López Martínez Pedro L. López de Alba Jesús E. Castrejón Durán Víctor Cerdà Martín 《Mikrochimica acta》2006,153(3-4):139-144
1-Naphthylamine (NPA) is one of the main degradation products of pesticides derived from naphthalene, and a well-known bladder
carcinogen in men. The Griess assay is used for NPA determination because of its high sensitivity and selectivity. The azo
dye 4-(sulphophenylazo)-1-naphthylamine is formed, which shows a peak maximum at 540 nm. After optimizing multisyringe flow
injection analysis (MSFIA) parameters, the analytical characteristics of the method were obtained, with a working linear range
of 0.5 to 14 mg L−1, according to the equation A = 0.0738±0.0019 [NPA] + 0.0028 ± 0.0042, r = 0.9997. Values for RSD (%) and Erel (%) were calculated for the concentration levels of 0.5, 6 and 12 mg L−1; values obtained were 1.1, 0.4 and 0.3% for RSD and 0.8, 0.3 and 0.2% for Erel, respectively. LD was 0.01 mg L−1 and LQ was 0.04 mg L−1 NPA. The MSFIA procedure for the determination of NPA was applied to different water samples (well water, tap water, seawater,
and wastewater from the EDAR-1, Palma de Mallorca water treatment plant), with satisfactory results and a throughput of 90
samples per hour. 相似文献
17.
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
18.
Selective Indicator Reaction for Kinetic Determination of Traces of Manganese(II), Ribavirin and Tiazofurin 总被引:1,自引:0,他引:1
Gordana A. Milovanović Mira M. Čakar Nevenka B. Vučić Milan Jokanović 《Mikrochimica acta》2000,135(3-4):173-178
In this work it was established that, in the presence of ammonium carbonate, traces of manganese(II) catalyse the oxidation
of Nile Blue A by hydrogen peroxide, which enables its kinetic determination in the concentration range from 6.6 to 65.9 ng
cm−3, the detection limit being 8.0 × 10−2 ng cm−3. Antiviral/antitumour substances modify the catalytic activity of manganese(II): 1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide,
ribavirin, increases the catalytic effect of manganese(II), while 2-β-D-ribofuranosyl-thiazole-4-carboxamide, tiazofurin,
acts as an inhibitor. On the basis of these effects, a kinetic method for determining ribavirin concentrations from 0.5 × 10−1 to 4.0 × 10−1 μg cm−3 and tiazofurin concentrations from 0.3 to 2.6 μg cm−3 is proposed. The kinetics of the indicator reaction were studied in the presence of the substances examined, the kinetic
equations established, and the constants of the corresponding reaction rates calculated. The effect of temperature on these
reactions was also investigated. The method was applied to the determination of manganese(II) in mineral water and ribavirin
in pharmaceutical preparations.
Received December 16, 1999. Revision June 6, 2000. 相似文献
19.
Shanmugam Sreedaran Kuppannan Shanmuga Bharathi Aziz Kalilur Rahiman Raju Prabu Raman Jagadesh Nanjian Raaman Vengidusamy Narayanan 《Transition Metal Chemistry》2009,34(1):33-41
A series of trinuclear Cu(II) complexes have been prepared by Schiff base condensation of 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane
and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane with aromatic and aliphatic diamines, Cu(II)
perchlorate and triethylamine. The complexes were characterized by elemental and spectroscopic analysis. Electrochemical studies
of the complexes in DMF solution show three irreversible one-electron reduction processes around Epc
1 = −0.73 to −0.98 V, Epc
2 = −0.91 to −1.20 V and Epc
3 = −1.21 to −1.33 V. ESR spectra and magnetic moments of the trinuclear Cu(II) complexes show the presence of antiferromagnetic
coupling. The rate constants for hydrolysis of 4-nitrophenylphosphate by the Cu(II) complexes are in the range of 3.33 × 10−2 to 7.58 × 10−2 min−1. The rate constants for the catecholase activity of the complexes fall in the range of 2.67 × 10−2 to 7.56 × 10−2 min−1. All the complexes were screened for antifungal and antibacterial activity. 相似文献
20.
Wen-Kui Dong Gang Wang Shang-Sheng Gong Jun-Feng Tong Yin-Xia Sun Xiong-Hou Gao 《Transition Metal Chemistry》2012,37(3):271-277
Two new Cu(II) complexes, [Cu(L1)2] (1) and [Cu(L2)2] (2) (HL1 = (E)-3-bromo-5-chloro-2-hydroxy benzaldehyde O-methyl oxime; HL2 = (E)-3-bromo-5-chloro-2-hydroxy benzaldehyde O-ethyl oxime), have been synthesized and characterized by physicochemical and spectroscopic methods. X-ray crystallographic
analyses show that complexes 1 and 2 have similar structures, consisting of one Cu(II) atom and two L− units. In both complexes, the Cu(II) atom, lying on an inversion center, is four-coordinated in a trans-CuN2O2 square-planar geometry by two phenolate O and two oxime N atoms from two symmetry-related N,O-bidentate oxime ligands. Moreover,
both complexes form an infinite three-dimensional supramolecular structure involving intermolecular C–H···Br hydrogen bonds
and π···π stacking interactions between the metal chelate rings and aromatic rings. Substituent effects in the two complexes
are discussed. 相似文献