共查询到20条相似文献,搜索用时 31 毫秒
1.
T. Lindemann A. Prange W. Dannecker B. Neidhart 《Fresenius' Journal of Analytical Chemistry》1999,364(5):462-466
A new method for the simultaneous separation and determination of four arsenic species [As(III), As(V), monomethylarsonic
acid and dimethylarsinic acid], three selenium species [Se(IV), Se(VI) and selenomethionine] as well as Sb(III) and Sb(V)
is presented. The speciation was achieved by on-line coupling of anion exchange high-performance liquid chromatography (HPLC)
with inductively coupled plasma mass spectrometry (ICP-MS). Chromatographic parameters such as the composition and pH of the
mobile phase were optimised. Limits of detection are below 4.5 μg L–1 (as element) for Sb(III) and the selenium species and below 0.5 μg L–1 for the other species. Precisions of retention times were better than 2% RSD and of peak areas better than 8% RSD for all
the species investigated.
Received: 13 January 1999 / Accepted: 4 March 1999 相似文献
2.
A flow-injection method is proposed for the simultaneous catalytic determination of formaldehyde and methanol on the basis
of the catalytic action of formaldehyde upon the redox reaction between crystal violet and potassium bromate in a phosphoric
acid medium and on-line oxidization of methanol into formaldehyde using a lead dioxide solid-phase reactor. The indicator
reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of crystal violet at the maximum
absorption wavelength of 610 nm. A technique based on three sampling loops with a single injection valve is developed. The
flow-injection system produces a signal of main peak with two shoulders of the same height. The height of the shoulders corresponds
to the formaldehyde concentration, and the height difference between the shoulders and the main peak corresponds to the methanol
concentration. The detection limit is 0.1 μg/mL for formaldehyde and 1.0 μg/mL for methanol with the sampling rate of 10 samples
per hour. The relative standard deviations for 11 replicate determinations of formaldehyde (1.0 μg/mL) and methanol (10 μg/mL)
are 1.1 and 2.1%, respectively. The method has been successfully applied to the simultaneous determination of formaldehyde
and methanol in some gas samples.
The text was submitted by the authors in English. 相似文献
3.
Using hydraulic high-pressure nebulization (HHPN) for sample introduction, an on-line high-pressure flow system (HPLC system)
becomes a functional component of the ICP spectrometer. By placing additionally an HPLC column between the sample valve and
the high-pressure injection/nebulization nozzle, an improved species analysis is attained. An example is given by on-line
separation and determination of Cr(III)/Cr(VI) in real waste water samples with ICP/AES. The detection limit of each Cr oxidation
state is 4 μg L–1 with an analysis cycle time of 5 min. In comparison to conventional coupling of HPLC and ICP spectrometry a considerably
higher sensitivity is achieved. Using spiked samples the recovery of HHPN-ICP/AES was on an average better than 98% in contrast
to only 79% for Cr(VI) determination with a UV photometric reference method. Due to chromatographic separation of Cr(VI) from
matrix components and Cr (III), the technique no longer shows the typical spectral interferences caused by Ca (267.716 nm
Cr line) and Fe (283.563 nm Cr line).
Received: 2 August 1997 / Revised: 11 October 1997 / Accepted: 21 October 1997 相似文献
4.
M. Seelig N. H. Bings J. A. C. Broekaert 《Fresenius' Journal of Analytical Chemistry》1998,360(2):161-166
A comparative study was performed of 600 W capacitively coupled microwave plasmas (CMP) with different plasma gases (Ar,
N2 and air) and aerosol generation with the aid of a Légère pneumatic nebulizer. Detection limits with the different working
gases are in the order of 15–4000 ng/mL for Fe, Cr, Zn, Mg and Ca in aqueous solutions. The influence of organic solutions
on the stability of the plasma is discussed. The determination of Co, Cr, Fe, Mg and Ni in different oil samples by OES is
described, using an air-CMP and pneumatic nebulization after dilution of the oils by 20% with cyclohexane. The detection limits
for these elements are in the 100–400 ng/g range. Results obtained for a waste motor oil for the elements mentioned in the
concentration range of 4–50 μg/g were found to be in good agreement with those obtained by ICP-OES after digestion of the
oils at high pressure in PTFE vessels.
Received: 10 March 1997 / Revised: 23 May 1997 / Accepted: 30 May 1997 相似文献
5.
M. Seelig N. H. Bings J. A. C. Broekaert 《Analytical and bioanalytical chemistry》1998,360(2):161-166
A comparative study was performed of 600 W capacitively coupled microwave plasmas (CMP) with different plasma gases (Ar,
N2 and air) and aerosol generation with the aid of a Légère pneumatic nebulizer. Detection limits with the different working
gases are in the order of 15–4000 ng/mL for Fe, Cr, Zn, Mg and Ca in aqueous solutions. The influence of organic solutions
on the stability of the plasma is discussed. The determination of Co, Cr, Fe, Mg and Ni in different oil samples by OES is
described, using an air-CMP and pneumatic nebulization after dilution of the oils by 20% with cyclohexane. The detection limits
for these elements are in the 100–400 ng/g range. Results obtained for a waste motor oil for the elements mentioned in the
concentration range of 4–50 μg/g were found to be in good agreement with those obtained by ICP-OES after digestion of the
oils at high pressure in PTFE vessels.
Received: 10 March 1997 / Revised: 23 May 1997 / Accepted: 30 May 1997 相似文献
6.
Two spectrophotometric methods were applied to the simultaneous assay of chlorhexidine hydrochloride (CHL) and lidocaine hydrochloride (LIH) in pharmaceutical formulations. Using derivative spectrophotometry, CHL was determined by measurement of its first derivative
signal at 290 nm (peak to zero amplitude) in the concentration range 5–9 μg/mL, and LIH was analysed by measurement of its
second derivative signals at 272 and 276 nm (peak to peak amplitude) in the concentration range 160–480 μg/mL. With the partial
least-squares (PLS-2), the experimental calibration matrix was constructed using 9 samples. The concentration ranges considered
were 5–7 μg/mL for CHL and 220, 240, 260 μg/mL for LIH. The absorbances were recorded between 240 and 310 nm at every 5 nm. 相似文献
7.
H. Hegeds A. Gergely T. Veress F. Zsila 《Fresenius' Journal of Analytical Chemistry》1999,364(8):749-752
Determination of Se in biological materials was attempted by microwave-induced plasma mass spectrometry (MIP-MS). (1) Serum
samples were available after 10 times dilution with 0.5% nitric acid solution containing 0.1% Triton X-100. When oxygen gas
was inserted into the plasma gas (nitrogen) in order to improve the combustion, the sensitivity was reduced to 45%. The detection
limit of this method was 0.5 ng/mL. (2) Standard reference materials on commercial base were used to evaluate the accuracy
of the Se determination by MIP-MS after microwave digestion. In samples like bovine liver and human hair with Se concentrations
of more than 0.7 μg/g, the standard curve method after internal standard (IS) correction was acceptable. This procedure was
unsuitable for samples with low Se concentrations such as milk powder (certified value of Se 0.11 μg/g), or plant leaf samples.
(3) Instead of IS correction, the peak height of the spectrum was used for calculations from the matrix matched calibration
curve. The results of all materials were close to the certified values, even at 25 ng/g. The detection limit of the MIP-MS
with microwave digestion and IS correction was 0.05 ng/mL in standard solutions. The detection limit of the peak height method
was 0.1 ng/mL and was estimated to be < 20 ng/g in plant materials.
Received: 25 September 1998 / Revised: 15 February 1999 / Accepted: 18 February 1999 相似文献
8.
Ch. Lüdke E. Hoffmann J. Skole E. Ullrich 《Analytical and bioanalytical chemistry》2000,366(2):204-208
An element-specific detection method, based on atomic absorption spectrometry (AAS) using solar blind photocells instead
of a dispersion system, is described for the determination of Hg-, As-, and Se-species. Spectrometric investigations of AAS
background lamps for As and Se measured with a CsI-cathode photocell shows its quality as narrow band detector. Species determination
can be carried out subsequently to prior separation by HPLC or GC. The LODs for alkylated Hg species were below 1 ng/L, and
for methylated As species below 1 μg/L. The relative standard deviation was < 10%. With the components described the production
of cheap and automated dedicated speciation spectrometers is possible.
Received: 18 May 1999 / Revised: 6 September 1999 / Accepted: 13 September 1999 相似文献
9.
Khalid Hamad Abu-Shandi 《Analytical and bioanalytical chemistry》2009,395(2):527-532
A high-performance liquid chromatographic (HPLC) method with fluorescence detection for the quantification of vancomycin in
human plasma was developed and validated. The method includes an extraction of vancomycin by deproteinization with acetonitrile.
The analyses were carried out at 258 nm as the emission wavelength while exciting at 225 nm on a reversed-phase column (30 cm × 4 mm
i.d. × 10 μm Waters Associates μBondapak C18) using a mobile phase composed of methanol and phosphate buffer at pH 6.3. Vancomycin
was quantitatively recovered from human plasma samples (>96%) with high values of precision. The separation was completed
within 27 min. The calibration curve was linear over the range from 5 to 1,000 ng/mL with the detection and quantification
limits of 2 ng/mL and 5 ng/mL, respectively. This method is suitable for the routine assay of plasma samples.
Figure The effect of the deproteinization solvent on the signal of the interference peak at retention time of 15.0 min. The peak
which interferes with the peaks of Erythromycin and Vancomycin has been disappeared by using 2 mL acetonitrile as the deproteinization
solvent. 相似文献
10.
Kishikawa N Ohkubo N Ohyama K Nakashima K Kuroda N 《Analytical and bioanalytical chemistry》2011,400(2):381-385
Ubiquinone is an important biologically active compound in the living body. The determination of ubiquinone in human plasma
is useful for the investigation of bioavailability of ubiquinone and for early diagnosis of several diseases. Therefore, we
developed a high-performance liquid chromatography (HPLC) with chemiluminescence detection method for the analysis of ubiquinone
in plasma samples. The method is based on luminol chemiluminescence detection of super oxide anion that is generated by the
redox cycle reaction between ubiquinone and dithiothreitol. The HPLC system involved an octyl column with a mobile phase of
methanol. Ubiquinone eluted from the column was mixed with dithiothreitol and luminol solutions simultaneously, and generated
chemiluminescence was monitored by chemiluminescence detector. The calibration curve for standard ubiquinone solution was
linear from 0.09 to 43.2 μg/mL (0.45–216 ng on column) with the correlation coefficient of 0.999, and the detection limit
(S/N = 3) was 26 ng/mL (130 pg on column). Using the proposed HPLC method, the peak of ubiquinone in human plasma could be
clearly detected on the chromatogram without any interference from plasma components. 相似文献
11.
Natural fluorite is used for growing CaF2 boules from melt by an improved technique. Chemical treatment of the starting ore decomposes the accessory minerals, thus
producing small amounts of the oxides of Si, Al, and Fe insoluble in the melt, whereas the overall content of rare earth elements
(REEs) of hundreds of μg g−1, remains unchanged. Analytical techniques and optical measurements provide for assessing the concentration range and trends
in the distribution of residual metal impurities along the height of the boules. Solid sampling electrothermal atomic absorption
spectrometry (SS-ETAAS) gives good reproducibility for impurities’ distribution within a large concentration range of 0.1–10
μg g−1. The concentrations of Zn and Cu determined were found to vary within the lowest tenths of μg g−1 range in the starting portions of chemically treated fluorspar and a batch of boules produced subsequently. The concentrations
of both elements show a decreasing trend towards the top section within the confidential interval, the width of which confirms
the definite in homogeneities in their distribution at those concentration levels. The Fe occurs in the boules below the detection
limit, while the content of lead diminishes rapidly towards their upper section, probably due to a shorter path in the liquid
phase before any vapour phase transition proceeds. A satisfactory correlation is found between the Pb concentration in ng
g−1-range and light-absorption peak intensity at 204 nm, the precise determination of which is impeded due to the overlapping
bands and the light-scattering effect. Reliable determination of impurities enables optimisation of the basic purification
— growing stages for the production of high grade crystals. 相似文献
12.
J. A. Salonia R. G. Wuilloud J. A. Gásquez R. A. Olsina L. D. Martinez 《Analytical and bioanalytical chemistry》2000,367(7):653-657
An on-line zinc preconcentration and determination system implemented with inductively coupled plasma atomic emission spectrometry
(ICP-AES) associated with flow injection (FI) was studied. The zinc was retained as zinc-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol
(Zn-(5-Br-PADAP)) complex at pH 9.2. The zinc complex was removed from the knotted reactor (KR) with 30% v/v nitric acid.
An enrichment factor of 42 was obtained for the KR system with respect to ICP-AES using pneumatic nebulization. The detection
limit for the preconcentration of 10 mL of aqueous solution was 0.09 μg/L. The precision for 10 replicate determinations
at the 5 μg/L Zn level was 2.3% relative standard deviation (RSD), calculated with the peak heights obtained. The calibration
graph using the preconcentration system for zinc was linear with a correlation coefficient of 0.9997 at levels near the detection
limits up to at least 100 μg/L. The method was succesfully applied to the determination of zinc in river water samples.
Received: 27 December 1999 / Revised: 14 March 2000 / Accepted: 15 March 2000 相似文献
13.
Juan Agüero José-Esteban Peris Eduardo San-Martín 《Fresenius' Journal of Analytical Chemistry》1999,363(3):289-293
An analytical method for detecting and quantifying cefotaxime in plasma and several tissues is described. The method was
developed and validated using plasma and tissues of rats. The samples were analyzed by reversed phase liquid chromatography
(HPLC) with UV detection (254 nm). Calibration graphs showed a linear correlation (r > 0.999) over the concentration ranges
of 0.5–200 μg/mL and 1.25–25 μg/g for plasma and tissues, respectively. The recovery of cefotaxime from plasma standards prepared
at the concentrations of 25 μg/mL and 100 μg/mL was 98.5 ± 3.5% and 101.8 ± 2.2%, respectively. The recovery of cefotaxime
from tissue standards of liver, fat and muscle, prepared at the concentration of 10 μg/g was: 89.8 ± 1.2% (liver), 103.9 ±
6.5% (fat) and 97.8 ± 2.1% (muscle). The detection (LOD) and quantitation (LOQ) limits for plasma samples were established
at 0.11 μg/mL and 0.49 μg/mL, respectively. The values of these limits for tissues samples were approximately 2.5 times higher:
0.3 μg/g (LOD) and 1.25 μg/g (LOQ). For plasma samples, the deviation of the observed concentration from the nominal concentration
was less than 5% and the coefficient of variation for within-day and between-day assays was less than 6% and 12%, respectively.
The method was used in a pharmacokinetic study of cefotaxime in the rat and the mean values of the pharmacokinetic parameters
are given.
Received: 25 May 1998 / Revised: 27 July 1998 / Accepted: 1 August 1998 相似文献
14.
A high-performance liquid chromatography–UV method for determining DCJW concentration in rat plasma was developed. The method
described was applied to a pharmacokinetics study of intramuscular injection in rats. The plasma samples were deproteinized
with acetonitrile in a one-step extraction. The HPLC assay was carried out using a VP-ODS column and the mobile phase consisting
of acetonitrile–water (80:20, v/v) was used at a flow rate of 1.0 mL min−1 for the effective eluting DCJW. The detection of the analyte peak area was achieved by setting a UV detector at 314 nm with
no interfering plasma peak. The method was fully validated with the following validation parameters: linearity range 0.06–10 μg mL−1 (r > 0.999); absolute recoveries of DCJW were 97.44–103.46% from rat plasma; limit of quantification, 0.06 μg mL−1 and limit of detection, 0.02 μg mL−1. The method was further used to determine the concentration–time profiles of DCJW in the rat plasma following intramuscular
injection of DCJW solution at a dose of 1.2 mg kg−1. Maximum plasma concentration (C
max) and area under the plasma concentration–time curve (AUC) for DCJW were 140.20 ng mL−1 and 2405.28 ng h mL−1. 相似文献
15.
M. A. Taher A. Mostafavi S. Z. Mohammadi Mobarakeh 《Journal of Analytical Chemistry》2007,62(11):1022-1027
This work assesses the potential of natural analcime zeolite as a sorbent for the preconcentration of palladium. Palladium
is quantitatively retained on modified analcime zeolite loaded with zincon using the column method in the pH range from 2.5
to 3.5 at a flow rate of 1 mL/min. The palladium complex was removed from the column with 5.0 mL of dimethylsulfoxide (DMSO)
and determined by third-derivative spectrophotometry. The detection limit is 0.03 μg/mL (signal-to-noise ratio = 3) in the
final solution. Since it is possible to retain 0.15 μg of palladium from 600 mL of solution passing through the column, elution
with 5.0 mL of DMSO gives a detection limit of 0.25 ng/mL for palladium in the initial aqueous solution. The calibration curve
is linear over the range 0.1 to 5.0 μg/mL of palladium(II) in the final solution with a correlation coefficient of 0.9996.
Seven replicated determinations of 5.0 μg of palladium in 5.0 mL dimethylsulfoxide gave a mean d
3
A/dλ3 (peak-to-peak signal between λ2 = 625 and λ1 = 654 nm) of 0.64 with a relative standard deviation of 1.2%. The sensitivity of the method (d
3
A/dλ3) is 0.5843 mL/μg of palladium(II) from the slope of the calibration curve. The interference of a large number of anions and
cations has been studied and the optimized conditions developed were utilized for the determination of trace palladium in
various synthetic and water samples.
The text was submitted by the authors in English. 相似文献
16.
A new linear-sweep voltammetric assay of nucleic acids (NAs) based on their interaction with crystal violet (CV) is proposed.
In a pH 3.5 Britton—Robinson (B-R) buffer solution, CV had an irreversible voltammetric reductive peak at −0.77 V and the
peak current greatly decreased by the addition of NAs. Under the experimental conditions, the decrease in the peak current
was used for the NAs assay 0.5–18.0 μg/mL of fish sperm DNA, 0.6–15.0 μg/mL of calf thymus DNA, and 0.8–12.0 μg/mL of yeast
RNA. The detection limits (3σ) were 0.32, 0.47, and 0.61 μg/mL for fsDNA, ctDNA, and yRNA, respectively. The binding reaction
can be completed after mixing DNA with CV within 10 min and the electrochemical response is stable for 2 h. There are seldom
interferences in this method and three synthetic samples were analyzed with satisfactory results. The stoichiometry of the
supramolecular complex with the binding number 3 and the binding constant 2.78 × 1014 is calculated using electrochemical data.
The text was submitted by the authors in English. 相似文献
17.
D. S. Tsar’kov E. S. Ryndina M. A. Proskurnin V. M. Shkinev 《Journal of Analytical Chemistry》2011,66(2):166-170
A novel method is proposed for the extraction-thermal lens quantification of cobalt with Nitroso-R-Salt based on the distribution
of the colored complex in a two-phase aqueous system on the basis of poly-ethylene glycol (PEG) and an ammonium sulfate solution followed by its thermal lens detection in the extract. The limit of detection is 0.3 μM
(20 ng/mL); the lower limit of the analytical range is 0.7 μM (40 ng/mL); the relative standard deviation for the concentrations
1–50 μM makes 1–3% (n = 6, P = 0.95). In the determination of cobalt by spectrophotometry under the same conditions, the detection limit is 10 μM (0.6
μg/mL) and the lower limit of the analytical range is 40 μM (2.5 μg/mL). The precision of thermal lens measurements in PEG
solutions is higher in comparison to that in aqueous ones because of the weaker interference of convection in aqueous solutions
of PEG. 相似文献
18.
Feasibility and limitations of direct coupling of high performance liquid chromatographic (HPLC) separation to microwave induced
plasma (MIP)-optical emission spectrometry (OES) for elementspecific detection was tested and compared to inductively coupled
plasma (ICP)-optical emission spectrometric detection on the basis of the Cr(III)/Cr(VI) speciation analysis of water samples.
Coupling was performed by a hydraulic high pressure nebulizer (HHPN) radiative-heating/watercooling interface which provides
about 20 % and 80 % aerosol yield in the case of helium and argon carrier gases, respectively. Desolvation efficiency of aqueous
solutions was approximately 80 %. Applying the ion-pair HPLC separation, the organic eluents and reagents in the MIP cause
a 50–75 % signal suppression for Cr(VI) and 25–50 % for Cr(III). In a pure aqueous solution the MIP Cr(VI) signal was by 20
% lower than that of Cr(III). These effects were lower using the ICP source, but they cannot be neglected. Easily ionizable
matrix elements (Na, Ca) can cause 70 % signal suppression in the MIP, and 20 % in the ICP. Therefore, species dependent calibration
is required in both cases. In the case of HPLC detection by MIP-OES, the detection limit was 13 ng for Cr(III), and 18 ng
for Cr(VI). Using the ICP-OES detection, the detection limit was 0.2 ng for Cr (III) and 0.4 ng for Cr (VI). The linear dynamic
ranges in both cases were two orders of magnitude.
Presented at the XVIIIth Slovak Spectroscopic Conference, Spišská Nová Ves, 15–18 October 2006. 相似文献
19.
Tianyou Peng Gang Chang Lei Wang Zucheng Jiang Bin Hu 《Analytical and bioanalytical chemistry》2001,369(5):461-465
A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic
powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry
(ETV-ICP-AES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization
of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time
and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that
a 10 μL 1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600 μg PTFE under the selected conditions.
Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using
standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization
(PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between
0.30 μg g–1 (Fe ) and 0.08 μg g–1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%.
Received: 28 August 2000 / Revised: 1 November 2000 / Accepted: 12 November 2000 相似文献
20.
In this paper, a novel method has been established to determine tiopronin using potassium ferricyanide as spectroscopic probe
reagent. It has been demonstrated that Fe(III) is reduced to Fe(II) by tiopronin, and the in situ formed Fe(II) reacts with
potassium ferricyanide to form soluble Prussian blue. Beer’s law is obeyed in the range of tiopronin concentration of 0.040–9.00
μg/mL at the maximal absorption wavelength of 735 nm. The linear regression equation is A = 0.0153 + 0.1605c (μg/mL) with a correlation coefficient of 0.9997 and the apparent molar absorption coefficient of 2.6 × 104 L/mol cm. The detection limit is 0.030 μg/mL and RSD is 1.3%. The parameters with regard to determination have been optimized
and the reaction mechanism has been discussed. This method has been successfully applied to determine tiopronin in pharmaceutical
and urine samples with satisfactory results. 相似文献