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1.
Summary A capillary electrophoretic method for the determination of thiosulphate, bromide, Fe(III)-EDTA chelate and free EDTA in spent
fixing solutions has been developed. Free EDTA was complexed with Ni(II) ions prior to analysis. The optimised separations
were carried out in a fused silica capillary (57 cm×75 μm I.D.) filled with a borate buffer (100mmol L−1 borate, 0.2 mmol L−1 tetradecyltrimethylammonium hydroxide, pH 8.5; applied voltage, −30kV) using direct UV detection at 214 nm. All four anions
were well separated in less than 4 min. The method was applied to the rapid monitoring of spent fixing solutions. 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.
Summary This paper discusses the use of capillary zone electrophoresis (CZE) with indirect UV detection for the separation and detection
of ions. By use of a 70 cm×75 μm i.d. capillary at −15 kV and an electrophoretic buffer containing sodium chromate, 1-butanol,
and cetyltrimethylammonium bromide as electroosmotic-flow modifier (pH 8) nine inorganic and organic anions were separated
in less than 10 min. By use of the same type of capillary at 20 kV and an electrophoretic buffer containing imidazole and
18-crown-6 (pH 5) eight cations were separated in less than 5 min. The different variables that affect the separation were
studied and optimized; the compounds were detected at low mg L−1 levels after hydrodynamic injection under pressure.
The method was tested with osmotically treated waters, and the results compared with those obtained by ion chromatography
for anion analysis and by atomic absorption spectroscopy for cation analysis. 相似文献
4.
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
5.
Separation and simultaneous determination of quinolone antibiotics by capillary zone electrophoresis
Summary The potential of capillary zone electrophoresis has been investigated for the separation and quantitative determination of
some quinolone antibiotics. The influence of different conditions, such as the nature and concentration of the electrophoretic
electrolyte, on migration time, peak symmetry, efficiency and resolution was studied. A buffer consisting of 100mm HEPES adjusted to pH 8.5 containing 10% (v/v) acetonitrile was found to furnish a very efficient and stable electrophoretic system for the separation of exoxacin, ciprofloxacin,
ofloxacin, oxolinic acid, nalidixic acid and pipemedic acid. A linear relationship between concentration and peak area for
each compound was obtained in the concentration range 0.25–40 μg mL−1; detection limits were approximately 0.25 ng mL−1. It was demonstrated that the method can be used for the simultaneous determination of these six antibiotics in serum and
urine samples. 相似文献
6.
Determination of organic acids in air by capillary electrophoresis and ion-exclusion chromatography 总被引:2,自引:0,他引:2
Summary A capillary electrophoretic (CE) method for the determination of organic acids in the low ppm range is described. The buffer
consisted of 5 mM 2,6-pyridinedicarboxylic acid and 0.5 mM cetyltrimethylammonium bromide, pH 5.6. The former served as background
electrolyte for indirect UV detection at 200 nm, whereas the latter was used to reverse electroosmotic flow. In <5 min 8 low
molecular mass organic acids (oxalic, formic, malonic, glutaric, glycolic, acetic, lactic and propanoic) and two inorganic
acids (hydrochloric and sulphuric) were separated. Detection limits for anions tested were 0.04 mg L−1 (lactic acid) to 0.6 mg L−1 (malonic acid).
The method was applied to the determination of organic acids in air samples. The CE results when compared with ion-exclusion
chromatography (IEC) agreed well. The use of electrokinetic injection in CE proved beneficial for preconcentration of organic
acids in real samples. Using electrokinetic injection, preconcentration factors ranging from 14 (hydrochloric acid) to 3 (propanoic
acid) were obtained.
Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999 相似文献
7.
Qiong He Tian Gan Dongyun Zheng ShengShui Hu 《Journal of Solid State Electrochemistry》2010,14(6):1057-1064
Simple and sensitive electrochemical method for the determination of nitrite, based on a nano-alumina-modified glassy carbon
electrode (GCE), is described. Nitrite yields a well-defined oxidation peak whose potential is 0.74 V at the nano-alumina-coated
GCE in 0.1 mol L−1 phosphate buffer (pH 5.0). Compared with bare GCE, the nano-alumina-modified GCE has evident catalytic effect towards the
oxidation of nitrite, and its peak current can be significantly enhanced. Some of the experimental parameters were optimized
for the determination of nitrite. The oxidation peak current was proportional to nitrite concentration in the range of 5.0 × 10−8–1.1 × 10−3 mol L−1, and a detection limit of 1.0 × 10−8 mol L−1 was obtained. This method has been successfully used to the determination of nitrite in sausage sample. Furthermore, results
obtained by the method have been compared with spectrophotometric method. 相似文献
8.
It has been found that gold nanoparticles (nano-Au) enhance the chemiluminescence (CL) of the luminol–hydrogen peroxide system
and that estrogens inhibit these CL signals in alkaline solution. CL spectra, UV–visible spectra, X-ray photoelectron spectra
(XPS), and transmission electron microscopy (TEM) were used to investigate the mechanism of the CL enhancement. On the basis
of the inhibition, a flow-injection CL method has been established for determination of three natural estrogens. Under the
optimized conditions, the linear range for determination of the estrogens was 0.07 to 7.0 μmol L−1 for estrone, 0.04 to 10 μmol L−1 for estradiol, and 0.1 to 10 μmol L−1 for estriol. The detection limits were 3.2 nmol L−1 for estrone, 7.7 nmol L−1 for estradiol, and 49 nmol L−1 for estriol, with RSD of 2.9, 2.6, and 1.8%, respectively. This method has been used for analysis of estrogens in commercial
tablets and in urine samples from pregnant women. 相似文献
9.
Summary The application of capillary zone electrophoresis to the study of interactions betweenBacillus subtilis tryptophanyl-tRNA synthetase (TrpRS) and tRNATrp is described. Significant changes in peak shape of tRNATrp incubated with TrpRS indicated the occurrence of interactions between TrpRS and tRNATrp in pH 8.0 Tris-HCl buffer containing 0.1 mmol L−1 EDTA and 1 mmol L−1−5 mmol L−1 mgCl2. Addition of Mg2+ decreased the electrophoretic mobility of tRNATrp, which illustrated that conformation of tRNATrp depended on Mg2+. The dissociation constant of the TrpRS-tRNATrp complex was estimated to be 0.63 μmol L−1 at 25°C in buffer solution. 相似文献
10.
Summary Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determination of inorganic anions
and carboxylic acids. However, there are few reports on direct UV detection of these solutes in real samples. This paper describes
the use of direct UV detection of inorganic anions and organic acids in environmental samples using co-electroosmotic capillary
zone electrophoresis (co-CZE) at 185 nm. The best separation and detection of the solutes was achieved using a fused silica
capillary with an electrolyte containing 25 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide (TTAB) and 15% acetonitrile
(v/v) at pH 6.0. Four common inorganic anions (Cl−, NO2
−, NO3
− and SO4
2−) and 11 organic acids (oxalic, formic, fumaric, tartaric, malonic, malic, citric, succinic, maleic, acetic, and lactic acid),
were determined simultaneously in 15 min. Linear calibration plots for the test solutes were obtained in the range 0.02–0.5
mM with detection limits ranging from 1–9 μM depending on the analyte. The proposed method was successfully used to determine
inorganic anions and carboxylic acids in soil and plant tissue extracts with direct injection of the sample. 相似文献
11.
K. K. Verma A. J. H. Louter A. Jain E. Pocurull J. J. Vreuls U. A. Th. Brinkman 《Chromatographia》1997,44(7-8):372-380
Summary On-line solid-phase extraction-gas chromatographyion-trap tandem mass spectrometry (SPE-GC-MS/MS) has been used for the trace-level
determination of polar and apolar pesticides. The SPE-GC interface, an Autoloop 2000, was operated at an injection temperature
of 90°C which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. Rectilinear calibration
curves were obtained for the analytes tested over a range of 0.1–500 ng L−1, using a sample volume of 10–100 mL for enrichment on an SPE cartridge packed with styrene-divinylbenzene copolymer. The
detection limits for the pesticides were in the 0.01–4 ng L−1 range. For a number of pesticides acceptable tandem mass spectra were obtained at levels as low as 0.1 ng L−1 level in real-life water samples.
As a demonstration of the applicability of this technique for inorganic anions, bromide and nitrite were converted into 4-bromoacetanilide
and 2-phenylphenol, respectively. The reaction products were pooled and subjected to simultaneous analysis by the present
method using full-scan mass spectrometric detection. The detection limits were 0.3 and 2 ng L−1, respectively. 相似文献
12.
Determination of magnesium,calcium, sodium,and potassium in blood plasma samples by capillary zone electrophoresis 总被引:1,自引:0,他引:1
A capillary zone electrophoretic assay has been developed and validated for analysis of magnesium, calcium, sodium, and potassium
in blood plasma samples. Optimum results were obtained with 20 mmol L−1 imidazole (pH 2.8) and 0.5 mmol L−1 oxalic acid containing 5% methanol, capillary temperature 25°C, applied voltage 30 kV, hydrodynamic injection time 3 s, and
a poly(vinyl alcohol)-coated capillary (i.d. 50 μm, total length 64.5 cm and effective length 56 cm). Indirect detection was
performed at 214 nm. Cadmium was used as internal standard. The migration times of magnesium, calcium, sodium, and potassium
were 4.25, 3.79, 3.96, and 2.79 min, respectively. The method was applied to the determination of magnesium, calcium, sodium,
and potassium in blood plasma samples. The results were compared with those from atomic absorption spectrophotometry and no
statistically significant difference was found (P>0.05).
This study was supported by the Turkish Republic, Prime Ministry State Planning Organization (Project Number: 98K121730) 相似文献
13.
Jiming Xu Yanping Wang Yuezhong Xian Hui Li Litong Jin K. Tanaka H. Haraguchi 《Chromatographia》2002,56(7-8):449-453
Summary A sensitive ion-exclusion chromatographic method has been developed for determination of oxalate, thiosulfate, and thiocyanate.
The method is based on separation of these anions on a polymethacrylate-based, weakly acidic cation-exchange resin (TSKgel
OApak-A) and detection by means of a glassy carbon (GC) electrode electrochemically modified with polyvinylpyridine (PVP),
palladium, and iridium oxide (PVP/Pd/IrO2). The electrochemical behavior of oxalate, thiosulfate, and thiocyanate at this chemically modified electrode (CME) have
been investigated by cyclic voltammetry. The results indicated that electrocatalytic oxidation of these anions by the electrode
was efficient and that the sensitivity, stability, and lifetime of the electrode were relatively high. Combined with ion-exclusion
chromatography the PVP/Pd/IrO2 electrode was used as the working electrode for amperometric detection of these anions. All linear ranges were over two orders
of magnitude and detection limits, defined asS/N=3, were 9.0×10−7 mol L−1 for oxalate, 6.7×10−7 mol L−1 for thiosulfate, and 5.6×10−7 mol L−1 for thiocyanate. Correlation coefficients were all>0.998. Coupled with microdialysis sampling the method has been successfully
applied to the determination of oxalate, thiosulfate, and thiocyanate in urine. 相似文献
14.
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
15.
J. Aupiais 《Journal of solution chemistry》2011,40(9):1629-1644
The electrophoretic mobilities of a few halide isotopes in aqueous solution have been evaluated at 25 °C and infinite dilution
by analyzing a combination of data obtained by capillary electrophoresis (CE) and conductance data extracted from the literature.
The effect of the temperature on the electrophoretic mobility has been thoroughly re-investigated to give the following temperature
dependence for the chloride ion at 25 °C: 1.565%/ °C in 5×10−3 mol⋅L−1 sodium chromate + 3×10−3 mol⋅L−1 sodium borate buffer. The precise determination of the electrophoretic mobility of chloride and bromide ions, including the
evaluation of their associated uncertainties, has been performed from conductance data spanning over 75 years. The electrophoretic
mobilities are found to be −(79.124±0.020)×10−9 m2⋅V−1⋅s−1 for Cl− and −(80.99±0.04)×10−9 m2⋅V−1⋅s−1 for Br−. Thanks to the precise determination of the temperature contribution and the re-evaluation of conductance data, the following
values have been found for 35Cl−, 37Cl−, 79Br−, and 81Br− (in 10−9 m2⋅V−1⋅s−1): −(79.18±0.02), −(78.95±0.06), −(81.04±0.04), and −(80.94±0.04). 相似文献
16.
A. Fernández-Gutiérrez C. Cruces-Blanco S. Cortacero-Ramírez A. Segura-Carretero 《Chromatographia》2000,52(7-8):413-417
Summary A highly sensitive and selective capillary ion electrophoretic (CIE) method has been established to show the applicability
of this separation technique to the determination of some of the anions usually found in water samples. The ions were monitored
by UV spectrophotometry with diode-array detection in presence of sulfonated calixarene compounds as organic modifiers in
the electrophoretic buffer medium. The instrumental variables affecting the sensitivity and resolution of the mixture were
carefully optimized. Snow water samples were been selected for analytical determination of iodide, chloride, sulfate, nitrite,
phosphate, and nitrate anions at ng mL−1 levels. The repeatability and reproducibility were calculated and were in the range 2.1 to 5.4% for the analytes determined. 相似文献
17.
This study investigates an off-line solid phase extraction (SPE) for improving the sensitivity in the capillary electrophoretic
(CE) analysis of four cephalosporins. Two sorbents—LiChrolut-C18 and Oasis HLB—were used in a SPE process to detect cephalosporins in natural waters (tap, river and hospital sewage) and
their performances were compared. By using Oasis HLB sorbent higher recoveries for river water were obtained (94–107% when
500 mL of sample were analyzed). The off-line SPE–CZE method was validated for river water with good detection limits (3 μg L−1) and the linearity ranged between 5 and 200 μg L−1. 相似文献
18.
Covalent modification of a glassy carbon electrode with penicillamine for simultaneous determination of hydroquinone and catechol 总被引:1,自引:0,他引:1
Liang Wang Peng Fei Huang Jun Yue Bai Hong Jing Wang Li Ying Zhang Yu Qing Zhao 《Mikrochimica acta》2007,158(1-2):151-157
A simple and highly selective electrochemical method has been developed for the simultaneous determination of hydroquinone
(HQ) and catechol (CC) at a glassy carbon electrode covalently modified with penicillamine (Pen). The electrode is used for
the simultaneous electrochemical determination of HQ and CC and shows an excellent electrocatalytical effect on the oxidation
of HQ and CC upon cyclic voltammetry in acetate buffer solution of pH 5.0. In differential pulse voltammetric measurements,
the modified electrode was able to separate the oxidation peak potentials of HQ and CC present in binary mixtures by about
103 mV although the bare electrode gave a single broad response. The determination limit of HQ in the presence of 0.1 mmol L−1 CC was 1.0 × 10−6 mol L−1, and the determination limit of CC in the presence of 0.1 mmol L−1 HQ was 6.0 × 10−7 mol L−1. The method was applied to the simultaneous determination of HQ and CC in a water sample. It is simple and highly selective. 相似文献
19.
Summary An ion-chromatographic procedure is described for the determination of selenium (VI) at μg L−1 level in the presence of anions and heavy metal ions. Maximum permissible concentrations and effects from each interfering
substance were investigated for the Se concentration range 12.5–1,000 μg L−1. The method, optimized for the detection of SeO
4
2−
, gives results suitable for speciation analysis. Total selenium can be determined after complete conversion to selenate ion
by oxidation with KMnO4. The detection limit of selenium is 4.8 μg L−1 (0.96 ng for 200 μL sample).
Paper presented at the 41st Pittsburgh Conference, New York, March 5–9, 1990. 相似文献
20.
We report a sensitive and convenient voltammetric method for the direct determination of 10-hydroxycamptothecin (HCPT). At
a multi-wall carbon nanotube (MWNT)-modified electrode, HCPT yields a very sensitive and well-shaped oxidation peak, which
can be used as analytical signal for HCPT determination. Compared with the poor electrochemical signal at the unmodified GCE,
the electrochemical response of HCPT at the MWNT-modified GCE was greatly improved, as confirmed by the significant peak current
enhancement. This result indicates that the MWNT-modified GCE has great potential in the sensitive determination of HCPT.
Based on this, a very sensitive and simple electrochemical method was proposed for HCPT determination after all the experimental
parameters were optimized. The newly-proposed method possesses very low detection limit (2 × 10−9 mol L−1) and wider linear range (from 1 × 10−8 to 4 × 10−6 mol L−1). Rapid and simple sample analysis is another advantage. Finally, this method was successfully demonstrated using HCPT drugs. 相似文献