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1.
Determination of glyphosate and aminomethylphosphonic acid in surface water and vegetable oil by capillary zone electrophoresis 总被引:1,自引:0,他引:1
A procedure is developed for the determination of glyphosate and aminomethylphosphonic acid in surface water and vegetable
oil by means of capillary zone electrophoresis with preliminary derivatization with phenylisothiocyanate and UV-detection.
The analytical ranges are 0.05–10 mg/L, the detection limits for glyphosate and aminomethylphosphonic acid make 0.005 and
0.02 mg/L, respectively. The analysis takes 1–2 hours, the relative standard deviation of the results of analysis does not
exceed 7%. 相似文献
2.
D. Abd El-Hady 《Journal of Analytical Chemistry》2009,64(11):1166-1173
A sensitive and selective capillary electrophoresis method with indirect UV-detection employing a high-sensitivity cell of
special design was used for the determination of sulphide in the presence of sulphate in drinking and wastewaters. The running
buffer consisted of chromate, tetradecyltrimethylammonium hydroxide, glutathione and polethylene glycol at pH 10.0. The use
of a high-sensitivity cell and the addition of polyethylene glycol were the key factors of improving sensitivity and selectivity
of the proposed method. The method was proved suitable for its intended use by applying the procedure starting from the calibration
of the CE instrument to validation of all experimental parameters. The resolution factor between sulphide and sulphate under
optimal conditions was found to be about 2.0. The limits of detection (LODs) of sulphide and sulphate were 2.0 and 0.3 ng/mL,
respectively. Analysis of standard mixtures of sulphide and sulphate gave good linearity in the ranges of 5.0–500.0 and 2.0–160.0
ng/mL, respectively, with correlation coefficients ranging between 0.994 and 0.996 at 95% confidence level. Application of
the proposed method to the analysis of water was successfully achieved and statistically confirmed. It is important to note
that in drinking water ultra trace concentrations of sulphide ions were successfully detected by the current method. 相似文献
3.
The chiral separation of dansyl-amino acids has been performed by capillary zone electrophoresis using ?β-cyclodextrin as
a chiral selector, urea as an additive and 2-propanol and methanol as organic modifiers. The enantiomeric separations of dansyl-amino
acids were investigated in aqueous medium and compared with the separation in mixed aqueous-organic medium as background electrolytes.
The separation conditions, (concentration of buffer, β-cyclodextrin, methanol, urea and the pH value of buffer) were optimized.
In the absence of organic modifier, only five pairs of 8 separated dansyl-amino acids were resolved when run separately. A
mixture of up to eight chiral amino acids can be baseline resolved in less than 19 min by β-cyclodextrin-modified capillary
zone electrophoresis with a buffer of 60 mmol L–1 H3BO3-KCl/40 mmol L–1 NaOH (pH 9.0), 4 mol L–1 urea, 100 mmol L–1β-cyclodextrin and 10% (v/v) methanol.
Received: 15 March 1999 / Revised: 10 May 1999 / Accepted: 12 May 1999 相似文献
4.
Chenxu Ding Xuejun Sun Xianen Zhao Wenchen Zhao Yulin Li Honglun Wang Yourui Suo Jinmao You 《Chromatographia》2008,67(3-4):245-251
A pre-column derivatization method for sensitive determination of oligopeptides, using the tagging reagent 2-(9-carbazole)ethyl
chloroformate (CEOC-Cl) followed by capillary electrophoresis (CE) with diode-array detection, has been developed. Maximum
yield close to 100% were observed when a three to fourfold molar excess of reagent was used at pH 9.0–10.0. Excess reagent
was extracted with n-hexane–ethyl acetate 9:1–10:1 (v/v); this enabled direct analysis using CE with no significant disturbance from the major fluorescent reagent degradation by-products.
The effects on the results of buffer pH and of SDS and organic modifier concentrations were examined. Good baseline resolution
in the separation of five CEOC-peptides was achieved with a 48.5-cm total length (effective length 40 cm) 50-μm inner diameter
capillary column. 相似文献
5.
Summary The possibility of determination of four cephalosporin antibiotics in clinical samples by capillary electrophoresis has been
investigated. The separation conditions for capillary zone electrophoresis (CZE) were studied in detail. The precision of
migration times measured by use of the optimized method was satisfactory (RSD<1%) and response was linearly dependent on concentration
over the approximate range 2–150 mg L−1 for all the compounds studied (cefuroxime, cefotaxime, ceftriaxone, and ceftazidime). Complete separation could be achieved
within 5 min. The CZE method was found to be highly suitable for direct determination of the antibiotics in clinical samples
such as wound drainage, cerebrospinal fluid, and urine; for serum, however, the use of micellar electrokinetic capillary chromatography
(MECC) was more advantageous.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
6.
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
7.
Summary Water, in concentrations up to 10%, has been added to organic solvents (dimethylsulphoxide,N-methylformamide, acetonitrile and methanol) used as the buffer solvents in electrophoresis media for non-aqueous capillary
electrophoresis. Anionic and cationic test substances have been used to study the effect on separation selectivity and efficiency.
The effect on the electroosmotic flow has also been studied. Water added in concentrations up to 0.5% had only a minor effect
on the separation selectivity, efficiency or electroosmotic flow in the systems studied. These results indicate that small
variations in the water-content of organic solvents are of only minor importance to the reproducibility of non-aqueous capillary
electrophoresis systems. The reproducibility of selectivity might, however, be slightly improved by adding 0.1–0.5% water,
because true non-aqueous solvents are likely to cause problems as a result of the variable absorption of water. 相似文献
8.
František Kvasnička Václav Janda Daniela Rousová Jiří Manda Lubica Kollerová 《Central European Journal of Chemistry》2005,3(1):137-145
Some oxyhalides can be found in drinking waters as inorganic disinfection byproducts. An on-line coupled capillary isotachophoresis—capillary
zone electrophoresis (CITP-CZE) method was developed for the analysis of chlorate, chlorite and bromate in water. The optimized
CITP-CZE electrolyte system consisted of the following: 10 mM—HCl+20 mM—β-Alanine (leading electrolyte), 5 mM—succinic acid
(terminating electrolyte), and 10 mM—succinic acid +5 mM—β-Alanine +0.1% HPMC (carrier electrolyte). A clear separation of
oxyhalides from other components of drinking water was achieved within 25 min. Method characteristics, i.e., linearity (0–200 ng/mL), accuracy (88–110%), intra-assay (3–5%), quantification limit (5–15 ng/mL), and detection limit
(2–5 ng/mL), were determined. Minimum labor requirements, sufficient sensitivity and low running cost are important attributes
of this method. It was found that the developed method is useful for the routine analysis of oxyhalides in water. 相似文献
9.
A fast capillary zone electrophoresis (CZE) method using dimethyl-β-cyclodextrin (DM-β-CD) as modifier with tetrabutylammonium
chloride (TBAC) as addition has been developed for the chiral separation of (±)-ephedrine ((±)-EP), (±)-pseudoephedrine ((±)-PP),
(±)-N-methylephedrine ((±)-MP), and (±)-norephedrine ((±)-NP). The electrophoretic separation was performed using a 35-cm
× 50 μm I.D. (30-cm effective length) fused silica capillary. Samples were introduced under electromigrated injection at 5
kV for 4 s, and the running voltage was 15 kV at the injector end of the capillary. Within 19 min, eight ephedrine compounds
were separated and detected at 210 nm. The method was successively applied to the determination of the ephedrine enantiomers
in the Chinese herbal extract from Ephedra sinica and its medicinal preparation (Xiaoerqing feiwan). Parameters affecting the resolution between (+) and (-)-enantiomers, such
as pH, cyclodextrin type and concentration, organic modifier, and tetraalkylammonium reagents, were reported.
The text was submitted by the authors in English. 相似文献
10.
Summary An on-line flow injection-solid-phase extraction-capillary zone electrophoresis (FI-SPE-CZE) method has been developed for
determination of cimetidine in human plasma. Sodium dodecylsulfate (SDS) was used as dynamic chemical modifier for elimination
of capillary contamination by biological macromolecules. FI on-line preconcentration and cleaning of the analyte by means
of a C18 microcolumn was performed automatically and CZE separation was performed consecutively without interruption of the applied
voltage and between-run-washing of the capillary. A detection limit of 8 μgL−1 (3×σ) was achieved at a sample throughput of 12h−1. The approach was successfully used for a pharmacokinetic study of cimetidine. 相似文献
11.
In this study, the choice of electrolyte systems for the separation and detection of a range of chlorophenoxyacetic acids and chlorophenols by means of capillary zone electrophoresis (CZE) is discussed. A series of acetate buffers over the buffering capacity pH range 4.03-5.5 were initially chosen for the separation. It was found that chlorophenoxyacetic acids could be separated at pH 4.03 and 4.5 but the most satisfactory separation of chlorophenols was obtained at pH 5.5. The factors affecting separation selectivity, including the addition of organic modifiers, was also studied. The use of 25% 2-butanol, 5% ethylene glycol and 10% acetonitrile as organic solvents resulted in the total separation of both classes of these compounds but poor peak shape of chlorophenols resulted and a number of chlorophenoxyacetic acids were not well separated. A borate-phosphate buffer gave improved peak shape of chlorophenols. Further improved separation of the components of the mixture was obtained by the addition of 2 mM fully methylated-beta-cyclodextrin to the 35 mM borate- 60 mM phosphate buffer at pH 6.5, maintaining good peak shape. In this case, separation of the two compound classes, chlorophenoxyacetic acids and chlorophenols, is achieved, with complete resolution of individual compounds in less than 5 min with high efficiency (of the order of 150,000 plates for the ca. 40 cm column). The method is applied to a commercial 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide mixture. 相似文献
12.
Determination of valproic acid (2-propylpentanoic acid) in human plasma by capillary electrophoresis with indirect UV detection 总被引:1,自引:0,他引:1
A rapid capillary zone electrophoresis method with indirect UV detection was developed and validated for the determination of valproic acid (VPA) in human plasma. The analyses were carried out under optimized conditions, using a buffer system composed of 15 mM benzoate and 0.5 mM cetyltrimethylammonium bromide at pH 6.0, and 25% v/v methanol; 2-hydroxybutyric acid was selected as the internal standard (IS). The capillary electrophoresis (CE) separation was carried out at a negative potential of 30 kV and the indirect UV detection was operated at 210 +/- 20 nm for all assays. The influence of buffer pH, ionic strength, concentration of electroosmotic flow (EOF) modifier and organic modifier on indirect signal response and migration behavior of the organic acid was investigated. Isolation of VPA from plasma was accomplished by a carefully implemented procedure using methanol as the precipitant agent. Using a high ratio of methanol to plasma for deproteinization (4:1), good absolute recovery of the analyte and satisfactory selectivity was obtained. The calibration line for VPA was linear over the 1-100 microg/mL concentration range. Sensitivity was high; in fact, the limit of detection (LOD) of VPA was 150 ng/mL and 450 ng/mL the limit of quantitation (LOQ). The results obtained analyzing real plasma samples from schizophrenic patients under polytherapy with VPA as well as antipsychotic drugs were satisfactory in terms of precision, accuracy and sensitivity. 相似文献
13.
A review of application of water-soluble cationic, anionic and nonionic polymers as pseudostationary phases in capillary electrophoresis (CE) and micellar electrokinetic capillary chromatography (MEKC) is presented. The effect of the structure of the polymers on the selectivity and efficiency of separation is discussed. A novel specially designed cationic polymer, 2,10-ionene, has been used for the separation of phenols. The polymer has hydrophilic and hydrophobic parts in its backbone. The polymer shows the best selectivity as a modifier in capillary zone electrophoresis (CZE)-mode, which allows the selective determination of both hydrophilic and hydrophobic phenols. 相似文献
14.
Capillary-electrophoretic determination of zinc and cadmium ions in aqueous solutions with ion-exchange preconcentration 总被引:1,自引:0,他引:1
L. N. Moskvin M. Ya. Kamentsev G. L. Grigor’ev N. M. Yakimova 《Journal of Analytical Chemistry》2010,65(1):99-102
An approach to choosing analyte preconcentration conditions for the subsequent capillary electrophoresis (CE) analysis of
the concentrate was substantiated using the simultaneous determination of zinc(II) and cadmium(II) trace concentrations as
an example. A CE procedure was developed for the determination of Zn and Cd with the following characteristics: The time of
the analysis, including analyte preconcentration from a 50-mL sample, was 30 min. The analytical ranges were 0.01–0.2 mg/L
for cadmium(II) and 0.005–0.1 mg/L for zinc(II). 相似文献
15.
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
16.
A rapid, reliable and simple capillary zone electrophoresis method for the determination of organic acids in beverages was developed. The complete separation of oxalic, formic, tartaric, malic, succinic, maleic, glutaric, pyruvic, acetic, lactic, citric, butyric, benzoic, sorbic, ascorbic and gluconic acids can be achieved in less than 3.5 min with a simple electrolyte composed by phosphate as the carrier buffer (7.5 mM NaH2PO4 and 2.5 mM Na2HPO4), 2.5 mM TTAOH as electroosmotic flow modifier and 0.24 mM CaCl2 as selectivity modifier, adjusting the pH at 6.40 constant value. Injection was performed in hydrodynamic mode (30 s) and the detection mode was UV direct at 185 nm. The running voltage was −25 kV at thermostated temperature of 25 °C. The method developed has been applied to several beverage samples with only a simple dilution and filtration treatment of the sample. The proposed method is fast because the separation time decrease two, four or, even, six times the separation times of the previous reported CZE methods. It is also simple and cheap due to a low consumption of chemicals and samples. These reasons permit it to be considered adequate for routine analysis of organic acids in beverage samples. 相似文献
17.
Halonitromethanes (HNMs) are one of the most cytotoxic and genotoxic classes found among the unregulated disinfection by-products
formed by the reaction of chemical disinfectants with natural organic matter in water. Typical methods used to determine these
compounds in water (mainly trichloronitromethane) are based on the Environmental Protection Agency (EPA) method 551.1 using
liquid–liquid extraction. A fast and straightforward method for the determination of the nine HNMs in water has been developed
using a static headspace (HS) coupled with gas chromatography–mass spectrometry (GC-MS). Important parameters controlling
headspace extraction were optimised to obtain the highest sensitivity: 250 μL of methyl tert-butyl ether (as a chemical modifier) and 6 g of anhydrous sodium sulphate were added to the water sample; an oven temperature
of 80 °C and an equilibration time of 20 min were also selected. The addition of a chemical modifier favoured the volatilisation
of all HNMs, increasing their signals up to approximately four times. Under optimum conditions, the method developed provides
limits of detection between 0.03 and 0.60 μg/L and a relative standard deviation of ∼6.0%. The developed method was validated
and then compared with the reference method EPA 551.1 for the analysis of tap and swimming pool water. A good agreement in
the results was observed, which corroborated the good performance of the proposed HS-GC-MS method. 相似文献
18.
The analytical potencies of ligand-exchange capillary electrophoresis (LECE) in regard to the determination of bioactive substances are discussed. As it is shown, complexation with copper(II) in the
electrophoretic determination with UV detection makes possible the determination of amino acids, amines, and sugars, which
do not absorb in the UV region, with the limits of detection 5–10 mg/L, and reduce the detection limits of the absorbing analytes,
such as tryptophane, tyrosine, and histamine by 2–3 times. Prospects for using online preconcentration for the reduction of
c
min are shown on an example of aliphatic amino acids, i.e., thirtyfold preconcentration is attained. LECE is shown to be applicable
to the simultaneous determination of glucose, Na(+), and K(+) in human blood serum. Also versions of ligand-exchange capillary electrophoresis with direct UV detection and capillary
zone electrophoresis with indirect one are compared in terms of efficiency, time of analysis, and limit of detection. The
potencies of the LECE method are compared with those of ligand-exchange chromatography. 相似文献
19.
Sensitive determination of fluoroquinolone residues in waters by capillary electrophoresis with laser-induced fluorescence detection 总被引:1,自引:0,他引:1
Manuel Lombardo-Agüí Laura Gámiz-Gracia Ana M. García-Campaña Carmen Cruces-Blanco 《Analytical and bioanalytical chemistry》2010,396(4):1551-1557
A sensitive capillary electrophoresis –laser-induced fluorescence method has been developed for the determination of six fluoroquinolones
of human (ofloxacin, lomefloxacin, and norfloxacin) and veterinary use (danofloxacin, enrofloxacin, and sarafloxacin) in different
kinds of water. Fluorescence detection was achieved using a He-Cd laser, with a wavelength of 325 nm. Separation was performed
in a fused-silica capillary, and conditions were optimized to obtain the most adequate separation and with the best sensitivity.
The separation was carried out in a 70-cm-long capillary (75 μm internal diameter, effective length 55 cm) by using a 125 mM
phosphoric acid separation buffer at pH 2.8, with 36% of methanol. The water sample pretreatment involved the separation and
preconcentration of the analytes by solid phase extraction. Two reverse-phase cartridges have been evaluated, namely Oasis
hydrophilic–liphophilic balance and Strata-X; the latter provided the best recoveries for the selected analytes. The method
shows very low detection limits (0.3–1.9 ng/L) with acceptable recoveries and precisions and has been successfully applied
to the analysis of well and tap water samples. 相似文献
20.
Paraskevas D. Tzanavaras Theano D. Karakosta Pantelis G. Rigas Demetrius G. Themelis Anastasia Zotou 《Central European Journal of Chemistry》2012,10(5):1459-1463
The first HPLC method for the separation of three paraben preservatives (methyl-, ethyl- and propyl parabens) using a core-shell analytical column is reported in this study. The separation was completed in less than 8 min at a low flow rate of 0.4 mL min−1 and an isocratic mobile phase containing 20% acetonitrile as organic modifier. The backpressure was < 200 bar in all cases, enabling the usage of conventional HPLC equipment. The proposed analytical procedure was validated for linearity (0.5–20 μg L−1), limits of detection (15–43 μg L−1) and quantification (50–142 μg L−1), selectivity, within day (1.3–1.5%) and day-to-day (3.4–4.6%) precision and accuracy. The proposed method has been applied to the determination of the selected paraben preservatives in commercially available hygiene wipes. The mean percent recoveries were found to be in the range of 98.0–98.4%. 相似文献