共查询到20条相似文献,搜索用时 31 毫秒
1.
2,6-O-diethyl-β-cyclodextrins were prepared and immobilized onto silica gel to develop a fluorosensor for dipyridamole. The analytical performance characteristics of the proposed sensor for analysis of dipyridamole were as follows: the detection limit was 0.8 nmol/L with a relative standard deviation of 1.4% for 10 determinations of 50 nmol/L of dipyridamole. The modification of β-CD improved the sensitivity and selectivity for measuring dipyridamole. The recommended method has been successfully tested for the determination of dipyridamole in clinical samples (urine and pharmaceutical preparations). 相似文献
2.
C. Brunori M. B. de la Calle-Gunti?as R. Morabito 《Fresenius' Journal of Analytical Chemistry》1998,360(1):26-30
Parameters for the reduction of Se(VI) to Se(IV) in HCl medium by heating in a microwave oven have been optimized. The reduction
resulted to be quantitative applying 100% power, corresponding to 600 W heating for 2 min in 6 mol/L or for 3 min in 4 mol/L
HCl. The behavior of selenomethionine and selenocystine under the optimized reduction conditions was studied in order to evaluate
a possible interference of these selenium species in the determination of Se(VI). The final determination of Se(IV), and Se(VI)
were done by hydride generation-atomic absorption spectrometry. The analytical merits of the method are reported. The method
was applied to the selective determination of Se(IV), and Se(VI) in spiked river and lake water.
Received: 6 December 1996/Revised: 1 April 1997/Accepted: 3 April 1997 相似文献
3.
M. Winklmair M. G. Weller J. Mangler B. Schlosshauer R. Niessner 《Fresenius' Journal of Analytical Chemistry》1997,358(5):614-622
A monoclonal antibody (Mab) with extraordinary sensitivity and high class selectivity to triazine herbicides is described.
With an enzyme-linked immunosorbent assay (ELISA) using Mab 4A54 IC50 values for terbuthylazine, atrazine, propazine and simazine below 0.1 μg/L (the EU maximum admissible concentration for individual
pesticides) have been obtained. Detection limits of 0.004 μg/L for terbuthylazine, 0.006 μg/L for atrazine, 0.003 μg/L for
propazine, 0.01 μg/L for simazine and 0.05 μg/L for deethylterbuthylazine could be achieved. Therefore, Mab 4A54 allows a
sum screening of these five triazines in a relevant concentration range. To our knowledge, this is the most sensitive antibody
to terbuthylazine at all and also the most sensitive Mab to all these four triazines. Another monoclonal antibody resulting
from the same immunization, clone 4A118, exhibits best sensitivity for propazine (detection limit: 0.02 μg/L) at lower cross-reactivity
to terbuthylazine and atrazine compared to clone 4A54. Affinity constants of both Mabs towards several triazines have been
calculated. The application of both Mabs for the analysis of triazines in water samples of different origin has been tested
and their resistance towards humic acid influence could be shown. A good correlation of the analysis of water samples with
GC and ELISA was observed.
Received: 17 February 1997 / Revised: 1 April 1997 / Accepted: 3 April 1997 相似文献
4.
Hitoshi Yamaguchi Sinji Itoh Shukuro Igarashi Kunishige Naitoh Ryosuke Hasegawa 《Fresenius' Journal of Analytical Chemistry》1998,362(4):395-398
Total reflection X-ray fluorescence (TXRF) analysis after the separation of matrix element was studied for the determination
of trace impurity elements (Ca, Sc, V, Cr, Mn, Fe, Co, Ni and Zn) in high purity copper. Matrix copper was removed by electrolysis
(0.2 A, 8 h) of a nitric acid solution. A 10 μL aliquot of the remaining solution of the electrolysis was dropped on a silicon-wafer
sample-carrier and dried in a vacuum. This was repeated five times and the precipitate of five 10 μL-aliquots was analyzed
by TXRF using a W-Lβ beam with an incident angle of 0.05 °. TXRF analytical values were obtained by using relative sensitivity
factors of the analytes to the internal standard element (Pd). Detection limits of the analytes ranges from 0.077 ng for Zn
to 0.785 ng for Ca.
Received: 25 December 1997 / Revised: 30 March 1998 / Accepted: 2 April 1998 相似文献
5.
M. M. Kamal 《Fresenius' Journal of Analytical Chemistry》1998,360(1):112-116
The adsorption and accumulation of NADH and the Cu2+-NADH system at the mercury electrode surface was examined using differential pulse cathodic stripping voltammetry (DPCSV).
The method was developed for analytical trace determination of NADH. Experimental and operational parameters for the quantitative
determination of NADH were optimized and the detection limit was found to be 9.960 × 10–8 mol/L. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered.
Received: 3 January 1997 / Revised: 1 April 1997 / Accepted: 4 April 1997 相似文献
6.
M. M. Kamal 《Analytical and bioanalytical chemistry》1998,360(1):112-116
The adsorption and accumulation of NADH and the Cu2+-NADH system at the mercury electrode surface was examined using differential pulse cathodic stripping voltammetry (DPCSV).
The method was developed for analytical trace determination of NADH. Experimental and operational parameters for the quantitative
determination of NADH were optimized and the detection limit was found to be 9.960 × 10–8 mol/L. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered.
Received: 3 January 1997 / Revised: 1 April 1997 / Accepted: 4 April 1997 相似文献
7.
You-Qun Song R. Yuan M. Ying Zhi-Qiang Li Y.-Q. Chai H. Cui G.-L. Shen Ru-Qin Yu 《Fresenius' Journal of Analytical Chemistry》1998,360(1):47-51
A new PVC membrane electrode based on the bis(benzoin)-semiethylenediamine (BBSEA) complex of Hg(II) is described which exhibits
excellent selectivity towards iodide, related to the unique interaction between the central Hg(II) and the iodide ion. The
electrode has a linear response to iodide from 5 × 10–7 to 5 × 10–4 mol/L with a slope of 58 mV/dec.(20°C). The response characteristics were investigated in detail and the mechanism of the
electrode was studied with AC impedance and quartz crystal microbalance (QCM) techniques. It can be used for iodide determinations
in drug preparations.
Received: 29 January 1997 / Revised: 17 April 1997 / Accepted: 20 April 1997 相似文献
8.
A new method for the preconcentration and determination of trace amounts of lead at the μg/L level in natural waters has
been established based on the formation of the thenoyltrifluoroacetone (TTA) complex with dibenzo-18-crown-6 (DB18C6) by means
of synergistic extraction and back-extraction combined with atomic absorption spectrometry (AAS). The effect of various factors
(synergism with TTA and DB18C6, shaking time, preconcentration factor, composition of the extracted species, and foreign ions
etc.) on the extraction and back-extraction of lead has been investigated in detail. The lead-TTA chelate in o-dichlorobenzene forms a stable adduct with DB18C6 as Pb(TTA)2 DB18C6. The stability constant (β) of the adduct determined by curve fitting method was log β = 4.2. The amount of lead in
natural waters such as tap water (Kanazawa University) and Kakehashi river (Komatsu City) determined by the present method
was found to be 0.64 ± 0.02 μg/L and 5.10 ± 0.03 μg/L, respectively.
Received: 14 July 1997 / Revised: 3 November 1997 / Accepted: 20 January 1998 相似文献
9.
Silvana V. Rodrigues Decio Nepomuceno Luci Viana Martins W. Baumann 《Fresenius' Journal of Analytical Chemistry》1998,360(1):58-61
The solubility of two related series of each three triazine compounds has been determined in supercritical CO2, at 40 °C and pressures between 80 and 220⋅105 Pa. A high pressure small volume cell with adjustable optical path and built-in circulation pump has been constructed to
be used with quartz windows in a Perkin Elmer UV-VIS spectral photometer. At 220 bar solubilities are between 0.3 and 25 g/L,
dependent on the specific triazine structure. The isothermal pressure dependence of the solubility could be modelled using
the pressure dependent dielectric constant of CO2 as the only variable.
Received: 30 October 1996/Revised: 3 April 1997/Accepted: 13 April 1997 相似文献
10.
A spectrophotometric method is proposed for the determination of 1,2-propylene glycol. It is based on the ADH/ AlDH catalyzed
oxidation of propylene glycol by NAD+. The NADH formed is measured at 340 nm. Alcohol dehydrogenase from equine liver was found to be much more effective than
that of yeast. No enantiomeric selectivity for s(+) propylene glycol was observed. A linear relation was found in the concentration
range from 5 to 50 mg/L. The method achieves a correlation coefficient of r = 0.996 and a relative standard deviation of 1.37%.
The limit of quantitation was calculated to 9.6 mg/L. Since the total reaction volume was restricted to 800 μL, only 2.8 units
of AlDH and 8 units of ADH were sufficient to develop the final absorption within 30 min.
Received: 16 April 1997 / Revised: 19 June 1997 / Accepted: 25 June 1997 相似文献
11.
A. H. Garde Åse Marie Hansen Thomas Block Nikolajsen 《Accreditation and quality assurance》2003,8(1):16-20
An inter-laboratory comparison study for cortisol in saliva is reported in the present study. Nine laboratories representing
four different methods participated in the study. Each laboratory measured five blind samples prepared from natural saliva
spiked with a pure certified reference material in the range 0–70 nmol/L. The average observed values were established as
means of eight laboratories, because one laboratory was excluded as an outlier. The natural content of cortisol in the pooled
saliva was 6.8 nmol/L. The recovery of the certified reference material was 83%–131% (164% for the outlying laboratory). For
five laboratories the 95%-confidence intervals of the recoveries did not cover 100%. The standard deviations for a concentration
of 10 nmol/L were estimated for each laboratory. They were 0.64–1.67 nmol/L (6.26 nmol/L for the outlying laboratory). The
present study emphasizes the need for an external proficiency-testing scheme and a certified reference material for cortisol
in saliva.
Received: 8 May 2002 Accepted: 3 September 2002 相似文献
12.
The adsorption behavior and differential pulse cathodic adsorptive stripping voltammetry of the pesticide Chlorpyrifos (CP)
were investigated at the hanging mercury drop electrode (HMDE). The pesticide was accumulated at the HMDE and a well-defined
stripping peak was obtained at –1.2 V vs Ag/AgCl electrode at pH 7.50. A voltammetric procedure was developed for the trace
determination of Chlorpyrifos using differential pulse cathodic adsorptive stripping voltammetry (DP-CASV). The optimum working
conditions for the determination of the compound were established. The peak current was linear over the concentration range
9.90 × 10–8– 5.96 × 10–7 mol/L of Chlorpyrifos. The influence of diverse ions and some other pesticides was investigated. The analysis of Chlorpyrifos
in commercial formulations and treated waste water was carried out satisfactorily
Received: 10 July 1997 / Revised: 1 April 1998 / Accepted: 6 April 1998 相似文献
13.
A novel determination method of electroinactive molecules by means of electrochemical technique is presented. A new self-assembled monolayer containing cyclodextrin (CD) is prepared with mono(6-o-p-tolylsulfonyl)-β-cyclodextrin. Although this derivatization process leads to a β-CD coverage of 10% of a full monolayer, this layer shows an effective host-guest response to ferrocene. The interfacial ferrocene complexation gives a response similar to that expected for a Langmuir adsorption isotherm yielding a stability constant of 4.2 ×104 mol-1· L and a maximum ferrocene coverage of 8.6×10-12 mol/cm2. The redox peak currents of the surface-confined ferrocene decrease upon addition of competing β-CD guest species to the solution, such as m-toluic acid (mTA) and sodium dodecyl sulfonate (SDS). This principle has been used for the determination of the electroinactive molecules, mTA and SDS in the concentration ranges of 0.8-2.7 μmol/L and 5-100 nmol/L, respectively. 相似文献
14.
G. Meissner Kari Hartonen M.-L. Riekkola 《Fresenius' Journal of Analytical Chemistry》1998,360(5):618-621
A method is developed for the determination of β-blockers in serum and urine at levels of 0.5 μg/mL. The technique uses a
combination of solid phase extraction (SPE) with in situ derivatization and supercritical fluid extraction (SFE) with subsequent
gas chromatography mass spectrometry. The optimization of the SFE step shows that a static extraction period can be eliminated.
The method gives good linearity (r = 0.991–0.999) and repeatability in the concentration range of 0.5 to 5 μg/mL. Relative
standard deviations for oxprenolol, propanolol and metoprolol were less than 5% in serum and 5–11% in urine.
Received: 23 May 1997 / Revised: 28 July 1997 / Accepted: 5 August 1997 相似文献
15.
Carbon paste electrodes, modified by Cu2O or CuO, were prepared and tested as sensors for hydrogen peroxide in aqueous solutions. They show a cathodic response to
the analyte ranging from 0.45 to 0.14 mA/cm2 for 1 mmol/L hydrogen peroxide for solutions of pH 5.2 and 7.3, respectively, at a working potential of –0.4 V vs. Ag/AgCl.
The cathodic operation mode used diminishes or excludes the possibility of anodic discharge of contaminants usually present
in biological fluids, and enables the use of the sensors in bioanalytical systems based on enzymes.
Received: 18 April 1997 / Accepted: 24 June 1997 相似文献
16.
Based on electrospray ionization – tandem mass spectrometry coupled to liquid chromatography (HPLC-ESI-MS/MS) a method for
separation and selective detection of 1,2,3,4-tetrahydro-β-carboline derivatives (THC) was developed. Retro-Diels Alder (RDA)
fragmentation of the tetrahydropyrido moiety resulted in the characteristic neutral loss of 73 amu for tryptophan-derived
THC-3-carboxylates. Accordingly, Pictet-Spengler condensation products of tryptamin exhibited product ions formed by loss
of 29 amu. However, THC-1-carboxylates as obtained by reaction of tryptamin with α-oxo acids also yielded product ions [M+H-73]+, apparently originating from the combination of RDA-cleavage plus subsequent decarboxylation. As result, one had to consider
the possibility of false-positive identification of THC-3-carboxylates in presence of isomeric THC-1-carboxylates. In order
to overcome these analytical pitfalls, the unequivocal identification of trace amounts of THC-3-carboxylates by HPLC-MS/MS
required the chromatographic separation of isomeric THC prior to selected reaction monitoring (SRM). Utilizing SRM, limits
of detection for various THC were established in the 10 ng mL–1 range. Subsequent analysis of food samples like seasoning sauce and yeast extract by HPLC-ESI-MS/MS revealed the presence
of tryptamin-derived 1,2,3,4-tetrahydro-β-carboline-1-carboxylic acid, 1-methyl-tetrahydro-β-carboline-1-carboxylic acid,
1-carboxyethyl-tetrahydro-β-carboline and 1-carboxyethyl-tetrahydro-β-carboline-1-carboxylic acid beside established THC-3-carboxylates
and -1,3-dicarboxylates.
Received: 31 July 1997 / Revised: 23 October 1997 / Accepted: 30 October 1997 相似文献
17.
Potential impurities such as nitrate, sulfate, nitrite, fluoride, formate, phosphate and oxalate were detected up to an analyte-to-excess
ratio (ATER) of 1:3 · 105 using an online two-dimensional isotachophoretic system. With the developed electrolyte system, consisting of two different
leading electrolytes, limits of detection (LOD) in the nmol/L range were realised by conductivity detection. These optimized
conditions were applied to the determination of these anionic impurities in different types of acetic acid and acetate salts
in order to evaluate and to verify their quality. Without sample preparation and or preconcentration, we were able to determine
the above mentioned analytes in the range of 0.00032–0.001% within 20 min. The results were compared with those obtained by
classical methods.
Received: 10 October 1997 / Revised: 9 December 1997 / Accepted: 10 December 1997 相似文献
18.
Potential impurities such as nitrate, sulfate, nitrite, fluoride, formate, phosphate and oxalate were detected up to an analyte-to-excess
ratio (ATER) of 1:3 · 105 using an online two-dimensional isotachophoretic system. With the developed electrolyte system, consisting of two different
leading electrolytes, limits of detection (LOD) in the nmol/L range were realised by conductivity detection. These optimized
conditions were applied to the determination of these anionic impurities in different types of acetic acid and acetate salts
in order to evaluate and to verify their quality. Without sample preparation and or preconcentration, we were able to determine
the above mentioned analytes in the range of 0.00032–0.001% within 20 min. The results were compared with those obtained by
classical methods.
Received: 10 October 1997 / Revised: 9 December 1997 / Accepted: 10 December 1997 相似文献
19.
Koichi Murayama Keiichi Yamada Roumiana Tsenkova Y. Wang Y. Ozaki 《Fresenius' Journal of Analytical Chemistry》1998,362(1):155-161
Near infrared (NIR) spectra in the 1300– 1850 nm region were measured for control serum solutions containing both albumin
and γ-globulin of various concentrations. Partial least squares two (PLS2) regression was applied to the NIR spectra to determine
simultaneously the concentrations of both proteins. For albumin, the correlation coefficient (R) of 0.988, the standard error
of calibration (SEC) of 1.61 g/L, the standard error of prediction (SEP) of 1.29 g/L, the relative standard deviation (RSD)
of 0.026 and the ratio of standard deviation of reference data in prediction to SEP (RPD) of 12.2 were obtained. For γ-globulin,
the corresponding values were 0.997, 1.36 g/L, 1.35 g/L, 0.0365 and 8.66, respectively. The regression coefficients (RCs)
of PLS factors were compared between albumin and γ-globulin, and the observed differences in the RCs were discussed based
upon the differences in the hydration between albumin and γ-globulin. In order to explore the effects of various metabolites
such as glucose, and cholesterol on the chemometrics models, the RCs for albumin and γ-globulin in the control serum solutions
were also compared with those for albumin and γ-globulin in phosphate buffer solutions previously studied. The results of
our experiments show that NIR spectroscopy with the use of PLS2 regression has considerable promise in nondestructive determination
of the concentrations of blood serum proteins.
Received: 31 December 1997 / Revised: 9 April 1998 / Accepted: 27 April 1998 相似文献
20.
Stankov-Jovanović VP Nikolić-Mandić SD Mandić LM Mitić VD 《Analytical and bioanalytical chemistry》2006,385(8):1462-1469
Pancuronium bromide (PCBr) inhibition effect on enzyme cholinesterase from pooled human serum (Che, EC 3.1.1.8 acylcholine
acylhydrolase) was used for development of a spectrophotometric kinetic method for PCBr determination in human serum and urine.
Optimal conditions for the basic and inhibitor reactions were established: pH=7.7 and substrate concentration c(benzoylcholine
chloride)=1.33 mmol/L. Kinetic parameters were also determined: Michaelis-Menten’s constant KM=0.40 mmol/L, maximal reaction rate Vmax=52.2 μmol/L min, inhibition constant Ki=0,56 μmol/L and IC50=1.31 μmol/L. Linear dependence between the reaction rate and inhibitor concentration exists in PCBr concentration range 8.20–68.25 nmol/L,
which corresponds to the real sample concentrations from 0.328 to 2.730 μmol/L. The method detection and quantification limits
were 2.01 nmol/L and 6.67 nmol/L, respectively. Precision of the method was tested for three pancuronium concentrations (10.70,
29.35 and 51.25 nmol/L). Relative standard deviation (RSD) was in the range 0.15–7.45%. Accuracy was examined by standard
addition method. Influence of the substances usually present in serum and urine on the reaction rate was tested. The developed
method was applied for PCBr content determination in serum model samples, urine model samples and in urine taken during surgery.
The method has good sensitivity, accuracy, precision and it is suitable for clinical practice.
相似文献