共查询到20条相似文献,搜索用时 46 毫秒
1.
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
2.
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
3.
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
4.
Flow injection chemiluminescence determination of isoniazid with electrogenerated hypochlorite 总被引:4,自引:0,他引:4
Jiachu Huang Chengxiao Zhang Zhujun Zhang 《Fresenius' Journal of Analytical Chemistry》1999,363(1):126-128
A flow-injection chemiluminescence method for the determination of isoniazid based on the sensitizing effect of isoniazid
on the chemiluminescence generating luminol-hypochlorite reaction is described. The hypochlorite was electrogenerated on-line
by constant current electrolysis, thus, eliminating instability of hypochlorite solution prepared from commercially available
sodium hypochlorite. The calibration graph is linear in the range 1 × 10–8 to 1 × 10–6 g mL–1, and the detection limit is 6 × 10–9 g mL–1. The relative standard deviation for determination of 5 × 10–8 g mL–1 is 2.8%. The proposed method has been successfully applied to the determination of isoniazid in pharmaceutical preparations.
Reveived: 2 May 1998 / Revised: 27 July 1998 / Accepted: 7 August 1998 相似文献
5.
A. Ruiz-Medina M. L. Fernández-de Córdova A. Molina-Díaz 《Fresenius' Journal of Analytical Chemistry》1999,363(3):265-269
A flow-through optosensor has been prepared for the sensitive and selective determination of pyridoxine (vitamin B6) in aqueous solutions. The sensor was developed in conjunction with a monochannel flow-injection analysis system with fluorimetric
detection using Sephadex SP-C25 resin as an active sorbent substrate. This method of determination is carried out without
any derivatization. The wavelengths of excitation and emission were 295 and 385 nm, respectively. When a HCl (10–3 mol L–1) / NaCl (3 × 10–2 mol L–1) solution is used as carrier solution, the sensor responds linearly in the measuring range of 5–200, 10–400 and 50–1800 ng
mL–1 with detection limits of 0.33, 0.67, and 5.70 ng mL–1 for 2000, 1000 and 200 μL of sample volume, respectively. The relative standard deviation for ten independent determinations
is less than 0.75% for 0.2 and 1.0 mL of sample volumes used, and 1.31% for 2.0 mL of sample volume used. The method was satisfactorily
applied to the determination of vitamin B6 in pharmaceutical preparations.
Received: 4 June 1998 / Revised: 16 July 1998 / Accepted: 6 August 1998 相似文献
6.
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
7.
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
8.
Qiaoyu Sun C. Wang Liangxi Li Hulin Li 《Fresenius' Journal of Analytical Chemistry》1999,363(1):114-117
A chemically modified carbon paste electrode was prepared by incorporating appropriate amounts of sodium humate(NaA). Palladium(II)
was selectively accumulated in a solution of Britton-Robinson(B-R) buffer (pH 2.8) onto the electrode surface in open circuit
mode. The subsequent electrochemical measurement was carried out by cyclic voltammetry (CV) and linear sweep anodic stripping
voltammetry (LSASV) in a supporting electrolyte of 1.0 M HCl. The obtained oxidation currents (Ipa1 and Lpa2) were proportional to the Pd(II) concentration in the range of 4.7 × 10–6 - 9.4 × 10–8 M. The developed method was applied to the quantitative determination of palladium in real samples.
Received: 6 March 1998 / Revised: 3 June 1998 / Accepted: 3 July 1998 相似文献
9.
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
10.
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
11.
A square wave voltammetric method whith 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. Ag|AgCl (saturated KCl). The iron (III) concentration in the alloy bath was 9.0 × 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 × 10–6 to 1.2 × 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.
Received: 4 April 2000 / Revised: 19 June 2000 / Accepted: 22 June 2000 相似文献
12.
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
13.
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
14.
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
15.
A fluorescence quenching method for the determination of vanadium (V) based on the vanadium- catalyzed oxidation of rhodamine
6G (R6G) with periodate in the presence of ethylenediaminetetraacetic acid disodium salt (EDTA) in sulfuric acid medium is
described. The fluorescence was measured with excitation and emission wavelengths of 525 and 555 nm, respectively. The calibration
graph for vanadium (V) had linear ranges of 3.0 × 10−9–1.5 × 10−8 mol/l and 1.5 × 10−8–4.0 × 10−8 mol/l, respectively. The detection limit was 1.7 × 10−9 mol/l. The proposed method was successfully applied to the determination of vanadium (V) in river water, rain water and cast
iron samples.
Received June 29, 2001 Revision October 9, 2001 相似文献
16.
A novel flow injection procedure has been developed for the determination of tannic acid based on the inhibition of the chemiluminescences
in luminol-H2O2-Manganese tetrasulfonatophthalocyanine (MnTSPc) system by tannic acid. The method is simple, rapid and sensitive with a detection
limit of 8 × 10−10 mol·L−1 and a linear range of 7 × 10−9–5 × 10−6 mol·L−1. The relative standard deviation is 1.9% for eleven measurements of 5 × 10−7 mol·L−1 tannic acid. The method has been successfully applied to the determination of tannic acid in real Chinese gall and hop pellets
samples. 相似文献
17.
Cecylia Wardak 《Central European Journal of Chemistry》2008,6(4):607-612
A new all plastic sensor for Co2+ ions based on 2-amino-5 (hydroxynaphtyloazo-1′)-1,3,4 thiadiazole (ATIDAN) as ionophore was prepared. The electrode exhibits
a low detection limit of 1.5 × 10−6 mol L−1 and almost theoretical Nernstian slope in the activity range 4.0 × 10−6–1 × 10−1 mol L−1 of cobalt ions. The response time of the sensor is less than 10 s and it can be used over a period of 6 months without any
measurable divergence in potential. The proposed sensor shows a fairly good selectivity for Co(II) over other metal ions.
The electrode was successfully applied for determination of Co2+ in real samples and as an indicator electrode in potentiometric titration of Co2+ ions with EDTA.
相似文献
18.
R. Schindler R. Vonach B. Lendl R. Kellner 《Fresenius' Journal of Analytical Chemistry》1998,362(1):130-136
A new process control methodology for the simultaneous determination of sugars, alcohols and organic acids in wine based
on multivariate evaluation of mid-IR transmission spectra of wine samples is presented. In addition to ethanol several lower
level wine components (glucose, fructose, glycerol, citric-, tartaric-, malic-, lactic- and acetic acid) were determined.
To establish a multivariate calibration model a set of 72 calibration solutions was prepared and measured, using a novel,
fully automated sequential injection (SI) system with Fourier transform infrared (FTIR) detection. The resulting spectra were
evaluated using a partial least square (PLS) model. The developed PLS model was then applied to the analysis of real wine
samples containing 79–91 g L–1 ethanol, 5.9–8.1 g L–1 glycerol, 0.4–6.9 g L–1 glucose, 1.5–7.5 g L–1 fructose, 0.3–1.6 g L–1 citric acid, 1.0–1.7 g L–1 tartaric acid, 0.02–3.2 g L–1 malic acid, 0.4–2.8 g L–1 lactic acid and 0.15–0.60 g L–1 acetic acid, yielding results which were in good agreement with those obtained by an external reference method (HPLC-IR).
The short analysis time (less than 3 min) together with high reproducibility makes the newly developed method applicable to
process control and screening purposes (average of the standard deviations calculated from four repetitive measurements of
six different real samples: ethanol: 0.55 g L–1, glycerol: 0.037 g L–1, glucose: 0.056 g L–1, fructose: 0.036 g L–1, citric acid: 0.020 g L–1, tartaric acid: 0.010 g L–1, malic acid: 0.052 g L–1, lactic acid: 0.012 g L–1 and acetic acid: 0.026 g L–1).
Received: 21 January 1998 / Revised: 5 March 1998 / Accepted: 6 March 1998 相似文献
19.
J. Rodríguez Flores J. J. Berzas Nevado G. Castañeda Peñalvo M. I. Rodríguez Cáceres 《Chromatographia》2003,57(7-8):493-496
Summary Capillary zone electrophoresis (CZE) has been used for direct determination of 6-thioguanine, methotrexate, and 5-fluorouracil
in human urine, by use of a fused-silica capillary (60.2 cm×75 μm i.d.). Separation was performed after hydrodynamic injection
for 7 s; the separation potential and capillary temperature were 25 kV and 35°C, respectively. A 45mm borate buffer solution (pH 9.2) was used as separation electrolyte. Under these conditions the analysis takes approximately
10 min and interday precision of migration times and corrected peak areas is satisfactory. A linear response over the concentration
range 3.0–20.0 mg L1 was observed for the three chemotherapeutic drugs in diluted human urine. Detection limits (s/n=3) for 6-thioguanine and methotrexate were approximately 1.60 mg L1 in diluted human urine; that for fluorouracil was 2.60 mg L1. A 2-ml volume of human urine was diluted with 2-mL of water and introduced directly into the electrophoresis system. CZE
was shown to be a good method with regard to simplicity, satisfactory precision, and sensitivity. This method resulted in
especially excellent recoveries for determination of methotrexate in all the different urine samples analysed (n=10). 相似文献
20.
A new spectrofluorimetric method was developed for the determination of trace amounts of coenzyme A (CoA). In the presence
of periodic acid (H5IO6), CoA can remarkably enhance the fluorescence intensity of the Tb3+–ciprofloxacin (CIP) complex at 545 nm in a buffer solution at pH 5.4; the enhanced fluorescence intensity of the Tb3+ ion is proportional to the concentration of CoA. The optimal conditions for the determination of CoA were also investigated.
The linear range and the detection limit for the determination of CoA were 6.08 × 10−6–1.64 × 10−5 and 2.1 × 10−8 mol L−1, respectively. This method is simple, practical and relatively free of interference from coexisting substances, and can be
successfully applied to assess CoA in injection and biological samples. Moreover, the enhancement mechanism of the fluorescence
intensity of the CoA–Tb3+–CIP system in the presence of H5IO6 is also discussed. 相似文献