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1.
An integrated continuous flow-capillary electrophoresis for the determination of soluble anions in soil samples is presented. A filtration probe coupled with the flow system, which is located before the capillary electrophoresis instrument, was designed to simplify sample pretreatment and to perform clean-up of aqueous soil suspensions. Only the manual weighing of the samples is needed. The extraction process for soil samples was optimized. The clear filtrate containing the soluble anions from soil was then passed to the capillary electrophoresis equipment by a home-made programmable arm. Chloride, sulfate, nitrite and nitrate were determined in soil samples at μg g–1 level and the results compared to manual reference methods. The precision expressed as relative standard deviation was in the range of ± 1.6 to ± 2.5% for the set of analytes determined. The procedure is up to 4 times faster than the competitive manual methods. 相似文献
2.
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
3.
A method based on solid phase extraction was developed for the determination of the herbicide triallate and its metabolite
2,3,3-trichloro-prop-2-en-sulfonic acid (TCPSA). Soil samples were extracted with methanol and diluted with water to yield
a methanol/water ratio of 1 : 4. Triallate was adsorbed on C18 cartridges while TCPSA was enriched on quaternary amine anion exchange resins. Cartridges were eluted with methanol/ethyl
acetate and methanol/sulfuric acid mixture, respectively. TCPSA methyl ester was formed using trimethyl orthoformate and subsequently
analyzed by GC/ECD. Determination limits of both target compounds were 5 μg/kg soil with recoveries of 100 ± 12% for triallate
and 57 ± 5% for TCPSA. In water analysis, determination limits were 0.05 μg/L with recoveries of 84 ± 14% for triallate and
100 ± 22% for TCPSA. In laboratory batch experiments, concentration of triallate decreased from 2690 to 1550 μg/kg soil within
59 days. 14 days after triallate application, TCPSA was determined to be 14 μg/kg which increased to 98 μg/kg soil at the
end of the incubation period. Soil/water distribution coefficients in loamy sand soil were 102 for triallate and 0.02 for
TCPSA which indicated a higher leaching tendency of the polar metabolite.
Received: 2 July 1997 / Revised: 15 September 1997 / Accepted: 25 September 1997 相似文献
4.
A. Merko?i A. Sastre J. L. Cortina C. Maccà 《Fresenius' Journal of Analytical Chemistry》1997,358(4):489-492
The acidity constant of di(2-ethylhexyl) thiophosphoric acid (DEHTPA) was investigated using potentiometric measurements
with a pH glass electrode. Owing to the low solubility of DEHTPA in pure water, its concentration and acidity constants were
determined by linearised pH-metric titration in 16.7% ethanol. A Ka value of (2.39±0.08)×10-4 was obtained. Quantitative determination of DEHTPA was performed by capillary zone electrophoresis (CZE) with carbonate buffer
(pH 11.0) as a background electrolyte, operating at −20 kV with direct UV detection at 210 nm. The migration time was 8.97 min
and the detection limit was 5 ppm.
Received: 2 September 1996/Revised: 19 November 1996/Accepted: 21 November 1996 相似文献
5.
Determination of citalopram by capillary electrophoresis is described. Compounds were separated at 28 kV in 75 μm i.d. fused silica capillary tubing (total length 85 cm, effective length 65 cm) with 10 mM borate buffer, pH 8.5, containing 10% (v/v) methanol as running buffer. Citalopram and propylparaben (IS) appeared at 3.5 and 5.5 min, respectively. Repeatable linear results were obtained. The limits of detection and quantification were 5.73 × 10−6 and 1.72 × 10−5 M, respectively. When citalopram was determined in a pharmaceutical tablet by capillary electrophoresis and by a UV-spectrophotometric method differences between the results were not significant. The citalopram content of tablets was 100.8 ± 2.95% of the label claim. The amount found in serum was 26.7 ± 0.1% of the free drug, indicating that 73.3% of the drug was bound to protein. 相似文献
6.
A. T. Abdul Rahman A. T. Ramli 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):653-657
A survey was carried out to determine terrestrial gammaradiation dose rates, the concentration level of 238U and 232Th and α and β activities for the surface soil in Ulu Tiram, Malaysia A 125 measurements were performed using a NaI(T1) gamma-ray
detector with crystal size of 1″ × 1″ on 15 soil samples collected from the site area about 102 km2
238U and 232Th concentrations were determined in soils by using hyper pure germanium (HPGe) gamma-ray spectrometry. The activity of α
and β from the surface soil was counted by using alpha beta counting system. The average value of 238U and 232Th concentrations in soil samples collected are 3.63±0.39 ppm within the range of 1.74±0.20 to 4.58±0.48 and 43.00±2.31 ppm
within the range of 10.68±0.76 to 82 10±4.01 ppm, respectively. The average estimate of α and β activity in soil samples collected
are 0.65±0.09 Bqg−1 and 0.68±0.08 Bqg−1, respectively. The average of terrestrial gamma-radiation dose rates measured in Ulu Tiram was found to be 200 nGy h−1, within the range of 96 to 409 nGy h−1. The population weighted outdoor annual effective dose was 1.2 mSv. 相似文献
7.
G. Horányi 《Journal of Solid State Electrochemistry》1998,2(4):237-241
Cyclic voltammetric study of platinized electrodes restricted to the potential range corresponding to the “double-layer region”
(350–700 mV on RHE scale) was carried out in acid medium in the presence of, HSO−
4, H2PO−
4, Cl− and ClO−
4 anions. It is shown that the shape of the voltammetric curves strongly depends on the nature of the anions present in the
system. The phenomena observed are ascribed to the specific adsorption of anions. A correlation is found between the results
of radiotracer adsorption studies (differential voltradiometric curves) and the voltammetric measurements.
Received: 24 September 1997 / Accepted: 25 November 1997 相似文献
8.
Giovannoli C Anfossi L Baggiani C Giraudi G 《Analytical and bioanalytical chemistry》2008,392(3):385-393
Experimental work performed was aimed at the assessment of a competitive capillary electrophoresis immunoassay with laser-induced
fluorescence (CEIA-LIF) detection for the determination of the Cry1Ab endotoxin from Bacillus thuringensis. The binding constant of a monoclonal antibody, raised against the insecticide protein Cry1Ab, was determined on a microplate
by indirect enzyme-linked immunosorbent assay (ELISA) and compared with that obtained in-capillary under nonequilibrium separation
conditions. The two binding constants appear comparable—(5.0 ± 1.2) × 106 M−1 and (9.06 ± 5.7) × 106 M−1—reflecting good preservation of the antibody binding behavior in the capillary electrophoresis format. These results allow
use of a calibration curve possible between 0.2 and 150 nM of endotoxin protein, with a limit of detection of 0.5 nM (33 μg L−1). Preliminary recovery experiments on maize extracts spiked with known amounts of Cry1Ab endotoxin also showed promising
results in detecting the toxin in complex real matrices. 相似文献
9.
Hillebrand S Garcia W Delmar Cantú M de Araújo AP Tanaka M Tanaka T Garratt RC Carrilho E 《Analytical and bioanalytical chemistry》2005,383(1):92-97
A capillary electrophoresis (CE)-based method for the in vitro detection and monitoring of nucleotide-triphosphatase activity
is described. This robust and reproducible method was used to investigate GTPase activity of a recombinant protein construct
containing the catalytic domain of Human SEPT4/Bradeion β (GST-rDGTPase). This example application demonstrates that the CE
technique can replace classical radioactive methods for GTPase activity assays and may be used as a routine analytical tool.
Enzyme kinetics of GST-rDGTPase was studied and yielded the following kinetic parameters: v
max = 1.7 μM min−1 ± 0.1, Km = 1.0 mM ± 0.3, and apKcat = 9 × 10−3 s−1. In addition the effect of co-factors such as Mg2+ and Mn2+ on the catalytic activity was investigated. The described analytical method was also shown to be useful to analyze diphosphated
and triphosphated forms of other nucleotides. 相似文献
10.
E. W. J. Hooijschuur Ch. E. Kientz J. Dijksman U. A. Th. Brinkman 《Chromatographia》2001,54(5-6):295-301
Summary The potential of microcolumn liquid chromatography (μlC) and capillary electrophoresis (CE) with on-line, flame photometric
detection (FPD) in the P-selective mode has been studied for determination of polar P-containing pesticides, glyphosate and
its main metabolite, aminomethylphosphonic acid (AMPA), ethephon, fosetyl-aluminium and acephate. Acephate was determined
by reversed-phase μLLC-FPD using large-volume injections with peak compression, the other compounds were determined by μLC-FPD
and CE-FPD using simple, large-volume injection procedures to obtain limits of detection of 7.5-500 ng·mL−1 and 1.0 μ·mL−1, respectively. The methods showed acceptable repeatability and robustness and were successfully applied for rapid and selective
determination of pesticides in fruit, vegetable and water samples. 相似文献
11.
R. Contreras V. S. Safont J. Andrés P. Pérez A. Aizman O. Tapia 《Theoretical chemistry accounts》1998,99(1):60-63
Recently, the proton affinity (PA) of ozone was experimentally determined by Cacace and Speranza [Science (1994) 265: 208]
using a bracketing technique that involved the proton transfer (PT) reactions: O3H++B⇒O3+BH+; for different Br?nsted bases B. These authors showed that the simple collision model is not adequate to describe PT. We
now present a theoretical model reflecting this bracketing procedure by explicitly introducing H-bonding complexing, dissociation
and PT contributions, to discuss the kinetic model that assumes that PT occurs through one elementary step. The methods used
include semiempirical density functional theory and ab initio Hartree-Fock methods. The procedure is gauged by using estimated
PA of ozone obtained from deprotonation reactions including the Br?nsted bases BNH3, H2O, HOCl, SO2, CH3F and Kr. The PA-obtained range was from 145.3 to 160.3 kcal/mol, in fair agreement with the experimental value of 148.0±3 kcal/mol.
The model seems to be fairly independent of the reference bases used to evaluate the PA. H-bonding effects appear to be a
determining factor to explain collision efficiencies.
Received: 5 August 1997 / Accepted: 25 September 1997 相似文献
12.
A method for the determination of copper in some sulfide minerals (lorandite, realgar, orpiment, marcasite, stibnite, galenite
and sphalerite) by Zeeman electrothermal atomic absorption spectrometry is presented. After the dissolution of samples, copper
was extracted with sodium diethyldithiocarbamate into different organic solvents (carbon tetrachloride, chloroform and methylisobutyl
ketone) at pH 11.0–12.0. The procedure was verified by standard addition. The standard deviation (SD) for 0.5 ng Cu is 0.01
ng, the relative standard deviation ranges from 3.5 to 5.5% and the detection limit of the method, calculated as 3 SD of the
blank, was found to be 0.05 μg · g–1.
Received: 26 May 1997 / Revised: 10 September 1997 / Accepted: 16 September 1997 相似文献
13.
The concentration of99Tc in IAEA reference materials has been determined with an ICP-MS as 0.86±0.07 Bq·kg−1 dry for IAEA-373 (grass) and 0.25±0.02 Bq·kg−1 dry for IAEA-375 (soil). These being sufficiently higher than the detection limits of typical measurement methods, both materials
can be used as reference materials for determining low-level99Tc in environmental samples. 相似文献
14.
A multi-purpose tubular flow-through sensor was constructed with an AgI-based membrane. The membrane was prepared by pressing
silver salts (AgI, Ag2S) and powdered Teflon. This membrane was incorporated in the tubular flow-through sensor body. A 2-mm diameter hole was drilled
through the center of the tubular sensor and the membrane, thus determining the active sensor volume of about 4 μL. The tubular
sensor with reference electrode was placed into a complex flow-injection system and used for the flow-through determination
of N-acetyl-L-cysteine, (NAC), in perchloric acid medium, pH = l. Linear dependence was established between the recorded
signal height and the concentration of NAC in the injected sample. The recorded change in potential for a decade change in
concentration, 62 mV {p (NAC)}–1, in the concentration range from 1 × 10–4 to 1 × 10–1 mol L–1, was based on the formation mechanism of the sparingly soluble deposit between silver and NAC on the surface of the sensitive
part of the membrane.
Received: 7 July 1997 / Revised: 22 September 1997 / Accepted: 26 September 1997 相似文献
15.
The stability of pH and certified amounts of nitrate, ammonia, total soluble nitrogen, total soluble organic carbon, magnesium,
sodium, potassium and phosphorus obtained by extraction from air-dried (40 °C) soil samples by 0.01 mol/L CaCl2 solution during storage at –18 °C, 4 °C, ambient temperature, 40 °C and 70 °C was investigated in one calcareous soil and
one acid sandy soil. Even at storage times of 45 and 90 days, extractable amounts changed. Extractable amounts of P, NH4-N, total soluble N and soluble organic C increased even at a storage temperature of 40 °C. The pH was lower for samples stored
at a temperature of 70 °C and also the Mg concentration became lower at elevated storage temperatures after 45 days in both
soils. It is suggested that reference materials certified for values using unbuffered extractants should be stored at a temperature
not higher than 4 °C.
Received: 13 May 1997 / Revised: 16 July 1997 / Accepted: 18 July 1997 相似文献
16.
Zhikum Si Wei Jiang Yuanju Ding Jingtian Hu 《Fresenius' Journal of Analytical Chemistry》1998,360(6):731-734
The fluorescence system of the Eu3+ (or/and Sm3+)-2-benzoyl-indane-1,3-dione(BID)-cetyltrimethylammonium bromide (CTMAB) was investigated at excitation wavelengths of 350
nm, and emission wavelengths at 612 nm for europium and 565, 606 and 650 nm for samarium, respectively. The system was used
for the determination of Eu and Sm in rare earth oxides and of BID in water. Europium or/and samarium could be determined
in the range of 1.0 × 10–9–1.0 × 10–5 mol/L and 2.0 × 10–8–5.0 × 10–5 mol/L, respectively; 1.0 × 10–6–2.0 × 10–5 mol/L of BID could also be determined.
Received: 5 March 1997 / Revised: 6 August 1997 / Accepted: 20 September 1997 相似文献
17.
Zhikum Si Wei Jiang Yuanju Ding Jingtian Hu 《Analytical and bioanalytical chemistry》1998,360(6):731-734
The fluorescence system of the Eu3+ (or/and Sm3+)-2-benzoyl-indane-1,3-dione(BID)-cetyltrimethylammonium bromide (CTMAB) was investigated at excitation wavelengths of 350
nm, and emission wavelengths at 612 nm for europium and 565, 606 and 650 nm for samarium, respectively. The system was used
for the determination of Eu and Sm in rare earth oxides and of BID in water. Europium or/and samarium could be determined
in the range of 1.0 × 10–9–1.0 × 10–5 mol/L and 2.0 × 10–8–5.0 × 10–5 mol/L, respectively; 1.0 × 10–6–2.0 × 10–5 mol/L of BID could also be determined.
Received: 5 March 1997 / Revised: 6 August 1997 / Accepted: 20 September 1997 相似文献
18.
Summary Urinary steroid metabolites were measured by capillary gas chromatography in 25 women (aged 33.3±12.0 years) with effluvium
and 16 control healthy laboratory workers women (aged 34.6±8.4 years). There was significant elevation in the level of a number
of steroids and steroid metabolites. The elevation of most steroid metabolites refers to the increased steroid secretion of
the adrenal and the high cortisol metabolites levels may be do to stress in some of the patients with effluvium.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997 相似文献
19.
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
20.
Min Ying R. Yuan Zhi-Qiang Li You-Qiang Song W.-X. Li H.-G. Lin G.-L. Shen R.-Q. Yu 《Fresenius' Journal of Analytical Chemistry》1998,361(5):437-441
A new solvent polymeric membrane electrode based on pyrazolone heterocyclic Schiff base complexes of Co(II) is described.
It shows a preferential response towards thiocyanate over a range of 2.0 × 10–6 to 1.0 × 10–1 mol L–1 with a slope of –60.2 ± 0.6 mV/dec. The selectivity sequence observed is thiocyanate > hydroxide > nitrite > iodide > perchlorate
> citrate > bromide > fluoride > chloride > nitrate > acetate > borate > sulfate > phosphate. The selectivity behavior is
discussed in view of axial coordination by uv/vis spectroscopy and the transfer process of thiocyanate across the membrane
interface is investigated by the ac impedance technique. The electrode was successfully applied to the determination of thiocyanate
in human urine as an indicator for distinguishing between smokers and non-smokers.
Received: 30 September 1997 / Revised: 9 December 1997 / Accepted: 13 December 1997 相似文献