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1.
Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Schöler 《Analytical and bioanalytical chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography – ultra violet – post column oxidation – cold vapour atomic absorption spectrometry) for
the determination of methylmercury at background levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.
Received: 23 November 1995/Revised: 16 April 1996/Accepted: 20 April 1996 相似文献
2.
Shihui Si Fenglian Ren Wen Cheng Shouzhuo Yao 《Analytical and bioanalytical chemistry》1997,357(8):1101-1105
To obtain new coatings for the preparation of piezoelectric immunosensors, the anodic polymerization of o-aminophenol (oAP),
o-phenylenediamine (oPD) and m-phenylenediamine (mPD) onto a gold-plated crystal has been studied. The possibility of immobilizing
an antibody (anti-S. paratyphi A) onto the crystal via the electropolymerized films was investigated. The poly-mPD film gave
the best results for immobilizing the antibody. With antibodies crosslinked on the poly-mPD film, a piezoelectric immuno-assay
for the detection of S. paratyphi A was proposed. The shift (ΔF=F20s−F400s, Hz) between the frequency at 20 s after the addition of sample (F20s), and that of 400 s (F400s) was used to construct a calibration graph, and shortening of the assay time was achieved. The S. paratyphi A concentration
in the range of 105–109 cells/ml can be measured by this method.
Received: 9 May 1996/Revised: 6 September 1996/Accepted: 19 September 1996 相似文献
3.
Shihui Si Fenglian Ren Wen Cheng Shouzhuo Yao 《Fresenius' Journal of Analytical Chemistry》1997,357(8):1101-1105
To obtain new coatings for the preparation of piezoelectric immunosensors, the anodic polymerization of o-aminophenol (oAP),
o-phenylenediamine (oPD) and m-phenylenediamine (mPD) onto a gold-plated crystal has been studied. The possibility of immobilizing
an antibody (anti-S. paratyphi A) onto the crystal via the electropolymerized films was investigated. The poly-mPD film gave
the best results for immobilizing the antibody. With antibodies crosslinked on the poly-mPD film, a piezoelectric immuno-assay
for the detection of S. paratyphi A was proposed. The shift (ΔF=F20s−F400s, Hz) between the frequency at 20 s after the addition of sample (F20s), and that of 400 s (F400s) was used to construct a calibration graph, and shortening of the assay time was achieved. The S. paratyphi A concentration
in the range of 105–109 cells/ml can be measured by this method.
Received: 9 May 1996/Revised: 6 September 1996/Accepted: 19 September 1996 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.
For the determination of 16 PAHs in soils and sediment samples by GC/FID and GC/MS, the dynamic off-line supercritical fluid
extraction with both pure and modified carbon dioxide has been evaluated. The optimisation of extraction parameters was performed
for four individual groups of PAHs according to their number of aromatic rings (2–3 rings, 4 rings, 5 rings and 6 rings) by
varying pressure (200–510 bar), temperature (50–150 °C), extraction fluid volume (10–50 ml), and the methanol modifier concentration
(0–10%). Using a five level spherical factorial experimental design the number of experiments required for optimisation was
45. In spiked soil samples extraction efficiencies of 80–100% were achieved for the individual groups of PAHs. At the optimal
set of conditions 10–30% lower recoveries of PAHs were obtained for the standard reference material NIST SRM 1941a (marine
sediment). The largest differences between extraction recoveries of native and spiked PAHs occurred at high molecular weight
PAHs. Using SFE efficiency data for the standard reference material, cluster analysis proved that dividing the 16 PAHs into
four groups according to their number of aromatic rings was appropriate and correct.
Received: 2 February 1996/Revised: 26 November 1996/Accepted: 30 November 1996 相似文献
6.
Comparison of sample digestion procedures for the determination of arsenic in certified marine samples using the FI-HG-AAS-technique 总被引:2,自引:0,他引:2
High-pressure digestion and a closed-vessel microwave heated system, both employing a mixture of nitric acid and hydrogen
peroxide as digesting agent, were tested for decomposing the certified samples of BCR 278 mussel tissue (Mytilus edulis) and of BCR 422 cod muscle to determine arsenic by use of FI-HG-AAS. While the microwave system is insufficient to mineralize
arsenic in marine samples (arsenic recoveries of 13±10% in BCR 278, 2±1% in BCR 422; n=4), high-pressure ashing at 300 °C
results in recovery percentages of 56±15% (n=4) in mussel tissue (BCR 278) and of 25±10% (n=4) in cod muscle (BCR 422). A
dry ashing procedure is given as a reference digestion, yielding complete recoveries of arsenic for both materials. The nitrite
interference arising during measurement can be entirely overcome by using an amino sulfuric acid concentration of about 350 mmol/L
in the solutions for measurement.
Received: 30 April 1996/Revised: 12 July 1996/Accepted: 16 July 1996 相似文献
7.
A mixture of manganese dioxide and hydrochloric acid has been used for the accurate and precise determination of gold in
various gold-bearing matrices. Results of intermethod comparison studies, F-test on variances, Mann-Whitney U-test, Spearman
rank correlation and regression analyses are presented. The recommended method can be applied to a quality control programme
and for the evaluation of reference materials. Various standard reference materials (SRM) of diverse matrices have been examined
to check the validity of the method and the results were found to be in very good agreement with the certified data. Sample
decomposition is straight forward [1–10 g sample (roasted at 600–700 °C)+5 g of MnO2+30 mL of 2 mol/L HCl]. Gold is coprecipitated with potassium tellurite using tin (II) chloride solution. The precipitate
is extracted into toluene and finally stripped back into aqua-regia solution for final nebulization into an air-acetylene
flame for atomic absorption spectrophotometry. The method is very simple and easily adaptable, and more convenient than conventional
methods involving aqua regia or a hydrobromic acid-bromine water mixture.
Received: 23 October 1995/Revised: 18 March 1996/Accepted: 23 March 1996 相似文献
8.
Chunshan Zhou Xingan Xiong Mingjian Wu G. Schwedt 《Analytical and bioanalytical chemistry》1997,357(7):894-896
A reversed-phase HPLC-method for the separation of mixtures of collectors for the flotation of heavy metal minerals is described.
It is based on a Nucleosil 5C18 column, isocratic elution and UV-detection at 238 nm. The mobile phase is methanol-water-5%
phosphoric acid (40:60:4, v/v). The method is applied to the determination of six collectors in aqueous solutions from flotation
processes. The relative standard deviations are 1.6–3.2% in the concentration range 2–10 mg/L. The detection limits are 1 μg/L
for 8-hydroxyquinoline, dimethylglyoxime and salicylic acid, 2 μg/L for salicylhydroxamic acid and 5 μg/L for benzenetriazol
and salicylaldoxime, respectively.
Received: 19 April 1996/Revised: 14 August 1996/Accepted: 23 August 1996 相似文献
9.
Determination of trace elements in AR grade alkali salts after preconcentration by column solid-phase extraction on TiO2 (anatase) 总被引:1,自引:0,他引:1
Column solid-phase extraction using TiO2 (anatase) as a solid sorbent was applied to preconcentrate traces of Cd, Co, Cu, Fe, Mn, Ni and Pb from AR grade alkali salts
prior to their measurements by atomic absorption spectrometry (AAS). Multi-element preconcentration was achieved from NaCl, KCl,
KNO3, NaNO3, CH3COONa, NaHCO3 and Na2CO3 solutions, whereas the sorption of trace elements from phosphates and sulfates is not quantitative. Optimal conditions (recoveries
of the analytes >95%) for solid-phase co-extraction of the most common heavy metal ions are proposed. The conditions for quantitative
and reproducible elution and subsequent AAS are established. A method of determination of trace elements in different salts
is proposed. It is characterized by precision, reproducibility and a high preconcentration factor. The solid-phase extraction
by TiO2, combined with ETAAS allows the determination of 0.1 ng g-1 Cd, 2 ng g-1 Co, 1 ng g-1 Cu and Ni, 0.5 ng g-1 Mn and 0.4 ng g-1 Pb.
Received: 1 April 1996/Revised: 24 June 1996/Accepted: 9 July 1996 相似文献
10.
M. A. Kabil S. E. Ghazy A. A. El-Asmy Y. E. Sherif 《Analytical and bioanalytical chemistry》1997,357(4):401-404
A sensitive and selective flotation procedure for the separation of microamounts of Co(II), Ni(II) and Cu(II) separately
or in admixture is described. The maximum separation rate (∼1) for 0.1 mmol/L of each analyte is achieved using 1 mmol/L of
both oleic acid (HOL) surfactant and 4-phenylthiosemicarbazide (HPTS) as a collector in the pH range 6–7. A method for the
simultaneous separation and microdetermination of the analytes is elaborated, based on adding excess HPTS and floating the
species with HOL at pH ∼6. The filtrate (which is clear brownish-yellow) obtained from the scum is used for the spectrophotometric
determination of Co(II) at 350 nm. The formation constants of 1:1 and 1:2 [Co(II):HPTS] species are 6.9×105 and 1.22×1010 L mol-1, respectively. Beer’s law is obeyed up to 9 μg/mL of Co(II) with a molar absorptivity of 1.15×104 L mol-1 cm-1. The precipitate in the scum layer is quantitatively collected, dissolved in aqua regia and aspirated directly into the flame
for the (AAS) determination of Ni and Cu. The procedure is successfully applied to some natural water samples. A mechanism
for the separation of the analytes is proposed.
Received: 23 January 1996/Revised: 1 April 1996/Accepted: 9 April 1996 相似文献
11.
Optimised method of coal digestion for trace metal determination by atomic absorption spectroscopy 总被引:1,自引:0,他引:1
Understanding the transport of trace elements through a coal-fired power plant requires reliable analytical methods for these
elements in all the ingoing and outgoing mass streams. Coal and different kinds of ashes comprise the most abundant mass streams
in such a plant. As a continuation of our previous work, we have optimised a digestion method for the AAS determination of
heavy metals in coal samples. It has become evident that complete dissolution of metals in coal samples and accurate results
in subsequent analysis can be obtained by means of applying pressurised digestion under microwave heating. The combination
of HNO3 (conc.) and HF (conc.) in the volume ratio of 50 : 1 attacked the sample well enough, and good recoveries for all the metals
studied were obtained. Surprisingly good results were obtained also when HNO3 alone was used as the digestion acid.
Received: 18 June 1998 / Revised: 23 September 1998 / Accepted: 24 September 1998 相似文献
12.
A successful flow-through system was developed for trace analysis of copper using DPASV with a glassy-carbon electrode. Periodical
chemical regeneration of the electrode with a 1 mol/L NaOH solution increased sensitivity and precision. The method was shown
to be applicable with a detection limit of 0.56 μg/L, with a determination time of less than 7 min per measurement (without
deaeration time). The drawback of the system is the 10 min deaeration time. The system gave an accuracy of 0.090±0.005% for
a certified reference material of low alloy steel containing 0.090±0.004% Cu. Applicability to various fresh water samples
with a Cu content between 1.57 and 13.11 μg/L with an RSD<2.36% is illustrated.
Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996 相似文献
13.
Determination of lead traces in water and liqueurs by derivative atom trapping flame atomic absorption spectrometry 总被引:3,自引:0,他引:3
H. Sun Li-li Yang De-qiang Zhang Wei-Xiao Wang Jian-min Sun 《Fresenius' Journal of Analytical Chemistry》1997,358(5):646-651
A new method for the direct determination of lead traces using derivative atom trapping flame atomic absorption spectrometry
(DAT-FAAS) with an improved water-cooled stainless steel trapping equipment in an air-acetylene flame was investigated. The
optimum conditions concerning the sensitivity were studied. For a 1 min collection, the characteristic concentration (given
as derivative absorbance of 0.0044) and the detection limit (3s) were 1.4 ng/mL and 0.27 ng/mL, respectively. This is 361
and 74-fold better than those of the conventional flame atomic absorption spectrometry (FAAS) and comparable to those of graphite
furnace atomic absorption spectrometry (GFAAS). The detection limit and sensitivity of DAT-FAAS for a 3 min collection time
were 2 and 3 orders of magnitude higher than those of conventional FAAS. The present method was applied to the determination
of lead in water and liqueur samples with a recovery range of 94–108% and a relative standard deviation of 3.5–5.6%.
Received: 10 January 1996/Revised: 9 December 1996/Accepted: 20 December 1996 相似文献
14.
A flow-through optosensor for tryptophan with C18 silica gel as a substrate is proposed. It has been developed in conjunction
with a flow-injection analysis system and is based on the retention of tryptophan on the C18 column and the enhancement of
its fluorescence. The detection limit is 25 ng mL-1 with a relative standard deviation of 2.9% for 7 determinations of 10 μg mL-1 of tryptophan. Most of the common species do not interfere. The method has been successfully applied to a pharmaceutical
preparation.
Received: 8 July 1996/Revised: 26 September 1996/Accepted: 30 September 1996 相似文献
15.
A successful flow-through system was developed for trace analysis of copper using DPASV with a glassy-carbon electrode. Periodical
chemical regeneration of the electrode with a 1 mol/L NaOH solution increased sensitivity and precision. The method was shown
to be applicable with a detection limit of 0.56 μg/L, with a determination time of less than 7 min per measurement (without
deaeration time). The drawback of the system is the 10 min deaeration time. The system gave an accuracy of 0.090±0.005% for
a certified reference material of low alloy steel containing 0.090±0.004% Cu. Applicability to various fresh water samples
with a Cu content between 1.57 and 13.11 μg/L with an RSD<2.36% is illustrated.
Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996 相似文献
16.
A. N. Araújo Joan Gracia Jose´ L. F. C. Lima Manel Poch M. Lu´cia M. F. S. Saraiva 《Analytical and bioanalytical chemistry》1997,357(8):1153-1156
A procedure is described for the colorimetric determination of iron in infant fortified formulas based on sequential injection
analysis (SIA). Iron(III) complexation with thiocyanate is used as colour developing reaction. The system enables the determination
of iron in the samples (after digestion by dry ashing and treatment with 0.2 mol/L nitric acid in the range of 0.50–20.0 mg/L,
consuming 140 μL of the sample and 8 mg thiocyanate per determination. The reactor geometry and the adjustment of the ionic
content of the calibration solutions is important for the accuracy of the results. A regression line according to the equation
[Fe(III) (mg/L)]SIA=−0.3(±0.4)+1.03(±0.04) [Fe(III) (mg/L)]FAAS was obtained after comparative analysis of a set of 12 samples. The measurement rate was 34 s, thus allowing to analyze 100
samples per hour with a relative standard deviation lower than 2%.
Received: 30 July 1996/Revised: 1 October 1996/Accepted: 4 October 1996 相似文献
17.
O. A. Platonova L. M. Bronstein S. P. Solodovnikov I. M. Yanovskaya E. S. Obolonkova P. M. Valetsky E. Wenz M. Antonietti 《Colloid and polymer science》1997,275(5):426-431
The preparation and properties of Co nanoparticles in polystyrene(PS)-poly-4-vinyl-py-ridine(PVP) micelles were studied.
Elementary Co was generated by two methods: (i) by reduction of micelles loaded with CoCl2, and (ii) by thermal decomposition of Co2(CO)8 in micel-lar solutions of such block copolymers. Co particles formed by both processes are effectively stabilized by the
block copolymer matrix and do not aggregate. For CoCl2 as a Co-source, the formed particles have a size less than 1 nm. Thermal treatment of such dried polymers at 200 °C for 2 h leads to spherical particles of 3–5 nm in size. The polymeric hybrid materials prepared in this way display remarkably
high values of magnetization at rather low Co contents in the polymer, i.e., we obtain a tenfold increase of the specific
magnetization density. Co2(CO)8 as a Co source, results in a more complex behavior. Co2(CO)8 dissolves in the solvent as well as in the micelle core where it is converted to an cationic–anionic complex involving the
4-VP units. The shape and size of the Co nanoparticles formed by thermolysis can be controlled by the balance of 4-VP/Co and
can be varied from spherical particles in the limit of lower Co loads being mainly attached to the micelle core to a star-like
and cubic morphology in case of excess of Co2(CO)8. Both superparamagnetic and ferromagnetic materials can be prepared. For ferromagnetic samples coercive force varies from
250 to 475 Oe depending on Co content and polymer sample.
Received : 27 September 1996 Accepted: 22 November 1996 相似文献
18.
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
19.
This study concerns the detection of natural steroid hormones in hair of cattle. Estradiol (E2) and testosterone (T) were chosen as representatives of estrogens and androgens. In particular, the influence of age, sex
and hair pigmentation on the steroid concentrations was investigated. Samples were obtained from numerous steers, cows, bulls,
and female and male calves. The extraction procedure for E2 and T from hair comprised liquid-liquid and solid-phase extraction and was followed by an essential high-performance liquid
chromatography (HPLC) step for further purification of the extracts. Final quantification was performed with specific enzyme
immunoassays (EIA). Lower E2-concentrations were detected in the hair of some steers, cows, and bulls (approximately 1 ng/g), in several of these hair
samples the concentrations of E2 were below the limit of detection. Testosterone was measured in the hair of steers (approximately 3 ng/g), cows (approximately
6 ng/g), and bulls (in average 15 ng/g). There was a significant difference in the testosterone concentrations of white (approximately
8 ng/g) and of black hair (approximately 33 ng/g) of bulls. In hair from all male and female calves, E2 and T were measured. The concentrations amounted approximately to 9 ng E2/g and 3 ng T/g for female calves and to 5 ng E2/g and 7 ng T/g for male calves. There was no significant influence of sex or hair colour on the steroid concentrations in
hair of calves. The results suggest that the method is a powerful means to detect natural steroid hormones in hair of animal
origin.
Received: 2 August 1996/Revised: 30 August 1996/Accepted: 5 September 1996 相似文献
20.
This study concerns the detection of natural steroid hormones in hair of cattle. Estradiol (E2) and testosterone (T) were chosen as representatives of estrogens and androgens. In particular, the influence of age, sex
and hair pigmentation on the steroid concentrations was investigated. Samples were obtained from numerous steers, cows, bulls,
and female and male calves. The extraction procedure for E2 and T from hair comprised liquid-liquid and solid-phase extraction and was followed by an essential high-performance liquid
chromatography (HPLC) step for further purification of the extracts. Final quantification was performed with specific enzyme
immunoassays (EIA). Lower E2-concentrations were detected in the hair of some steers, cows, and bulls (approximately 1 ng/g), in several of these hair
samples the concentrations of E2 were below the limit of detection. Testosterone was measured in the hair of steers (approximately 3 ng/g), cows (approximately
6 ng/g), and bulls (in average 15 ng/g). There was a significant difference in the testosterone concentrations of white (approximately
8 ng/g) and of black hair (approximately 33 ng/g) of bulls. In hair from all male and female calves, E2 and T were measured. The concentrations amounted approximately to 9 ng E2/g and 3 ng T/g for female calves and to 5 ng E2/g and 7 ng T/g for male calves. There was no significant influence of sex or hair colour on the steroid concentrations in
hair of calves. The results suggest that the method is a powerful means to detect natural steroid hormones in hair of animal
origin.
Received: 2 August 1996/Revised: 30 August 1996/Accepted: 5 September 1996 相似文献