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1.
A method is presented which is sensitive enough for the determination of vanadium (V) in marine organisms such as mussels and algae. It was sufficiently checked by a reference material and it was applied to V determination in blue mussels and brown algae from the German Bight. 相似文献
2.
D. Seo M. B. A. Vasconcellos M. G. M. Catharino E. G. Moreira E. C. P. M. de Sousa M. Saiki 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(1):459-463
Vanadium determination present in seawater is of great importance to evaluate marine contamination from industrial sources as well as to identify health hazards since mussels and other marine organisms are used as food. Besides, this evaluation in the Santos coast, SP, Brazil, is important, since this area is impacted by industrial and urban activities and discharges from ships and boats. In a previous study, V results obtained for transplanted mussel (active biomonitoring) were presented. This study aimed the V determination by passive biomonitoring by analyzing Perna perna mussels collected in natural environment, from three sites in São Paulo State coast: Cocanha Beach (reference site), Ponta de Itaipu and Palmas Island. Ninety individuals of mussels were collected in each site between September/08 and July/09 during the four seasons of the year. After shell removal and sample preparation, V was determined by instrumental neutron activation analysis. For analytical quality control, the NIST Standard Reference Material SRM 1566b Oyster Tissue was analyzed and the results presented good accuracy. The V concentrations in mussels on dry mass basis varied from 0.77 ± 0.02 to 3.56 ± 0.88 mg kg?1. Statistical tests were applied to the results showing differences on V concentrations among the sampling sites and season of sample collection. 相似文献
3.
A new analytical strategy was established to improve the determination and identification performance during analyses of
microcystins and diarrhetic shellfish poisoning (DSP) toxins in different matrices. Automated high performance size exclusion
chromatography (gel permeation chromatography, SEC) was applied for the clean-up of raw extracts from algae and mussel tissue
containing either microcystins or DSP toxins. The cleaned raw extracts are well suited for the direct determination of microcystins
and DSP toxins by HPLC/MS. The analyses of cleaned raw extracts containing microcystin by HPLC and UV/diode array detection
(DAD) revealed chromatograms without interfering peaks. Additionally, methods for the identification of unknown microcystins
and those not available as standards were developed and established. The proposed strategy is exemplarily demonstrated for
the analyses of a natural algae community from a lake in Slowakia and a naturally contaminated mussel from Portugal.
Received: 23 July 1999 / Revised: 9 September 1999 / Accepted: 16 September 1999 相似文献
4.
The main problem with routine analyses of pentachlorophenol (PCP) and sodium pentachlorophenolate (Na-PCP) in wood and wood-based
products is to determine critical PCP-contents. This task requires a reliable analytical method and statistical testing. An
analytical procedure is described, which permits the determination of PCP and Na-PCP with sufficient sensitivity and accuracy.
A medium size sieve (4 × 4 mm quadratic mesh) was found suitable for the grinding step. Different extraction techniques and
solvents were tested systematically. Extraction by a combination of ultrasonication and shaking in the solvent mixture toluene/sulfuric
acid showed best recoveries. The eluted PCP and Na-PCP were derivatized with acetic anhydride and determined by GC/ECD. The
limits of detection and determination were 0.14 mg/kg and 0.40 mg/kg, respectively.
Received: 6 August 1999 / Revised: 26 October 1999 / Accepted: 1 November 1999 相似文献
5.
Determination of trace metals in high purity gold 总被引:2,自引:0,他引:2
The possibility of using ETAAS or ICP-AES for the determination of trace amounts of Ag, Bi, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb,
Pd, Pt and Sb in pure gold is investigated. The influence of the matrix element on the atomization of the trace analytes is
studied and optimal instrumental parameters are defined. An analytical method based on matrix element reductive separation
followed by spectrometric determination of trace analytes is proposed as an alternative for the analysis of high purity gold.
Advantages and disadvantages of proposed analytical procedures from the viewpoint of achieved repeatability, reproducibility
and detection limits and of the duration of analysis are discussed.
Received: 16 August 1999 / Revised: 23 November 1999 / Accepted: 27 November 1999 相似文献
6.
C. G. Bruhn J. Y. Neira M. I. Guzmán M. M. Darder J. A. Nóbrega 《Fresenius' Journal of Analytical Chemistry》1999,364(3):273-278
The determination of Cr in digest solutions of mussels and non-fat milk powder by tungsten coil electrothermal atomic absorption
spectrophotometry (TC-ETAAS) is affected by interferences. This study reports a critical evaluation of chemical modifiers
that could be employed to correct these interferences. The chemical modifiers tested were: Mg [as Mg(NO3)2], Pd [as Pd(NO3)2], NH4NO3, ascorbic acid, and mixtures of these compounds. The less effective modifier was NH4NO3. The best effects, considering thermal stabilization and sensitivity, were obtained in mixtures of ascorbic acid plus Mg.
Chromium was determined by TC-ETAAS in certified reference materials of mussels and non-fat milk powder, and results were
comparable with those obtained by graphite furnace atomic absorption spectrophotometry (GFAAS).
Received: 19 June 1998 / Revised: 11 January 1999 / Accepted: 16 January 1999 相似文献
7.
Li Shunxin Qian Shahua Huang Ganquan He Fei 《Fresenius' Journal of Analytical Chemistry》1999,365(5):469-471
A novel method for the separation and preconcentration of Se(IV)/ Se(VI) with algae and determination by graphite furnace
atomic absorption spectrometry (GFAAS) has been developed. The Se(VI) is extracted with algae from the solution containing
Se(IV)/Se(VI) at pH 5.0, and the remaining Se(IV) is then preconcentrated pH 1.0. The detection limits (3σ, n = 11) of 0.16 μg L–1 for Se(IV) and 0.14 μg L–1 for Se(VI) are obtained using 40 mL of solution. At the 2.0 μg L–1 level the relative standard deviation is 2.6% for Se(IV) and 2.3% for Se(VI). The method has been applied to the determination
of Se(IV)/Se(VI) in sediment and water samples. Analytical recoveries of Se(IV) and Se(VI) added to samples are ?97 ± 5% and
102 ± 6% (95% confidence), respectively.
Received: 10 February 1999 / Revised: 21 June 1999 / /Accepted: 22 June 1999 相似文献
8.
A continuous flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-elution
procedure for the determination of iodide traces. Chromium (VI) is introduced into the flow system and is reduced to chromium
(III) in acid medium proportionally to the iodide present in the sample. The Cr(III) reduced by iodide is retained on a minicolumn
packed with a poly(aminophosphonic acid) chelating resin, while unreduced Cr(VI) is not retained. Reduced Cr(III) is preconcentrated
by passing the sample containing iodide through the system during 3 min, and is then eluted with 0.5 mol L–1 hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3σ) obtained is 2.5
μg L–1. Other ions typically present in waters do not interfere. The proposed method allows the determination of iodide in the range
6–220 μg L–1 with a relative standard deviation of 2.7% at a rate of 17 samples h–1. The method has been applied to the determination of iodide in tap and sea waters.
Received: 16 September 1999 / Revised: 15 November 1999 / Accepted: 19 November 1999 相似文献
9.
A nickel hexacyanoferrate modified electrode was constructed by mechanical immobilization. A reversible peak with midpoint
potential of 0.38 V was observed in cyclic voltammetry with 0.1 M NaNO3. Electrocatalytic oxidation of thiosulfate was effective on the modified electrode at a significantly reduced overpotential
of 0.5 V and at broad pH range. The modified electrode can be used for the determination of thiosulfate in the concentration
range of 7.0 × 10–4 to 5.6 × 10–3 M. It has been used for the amperometric determination of thiosulfate in photographic effluents. The results obtained were
in good agreement with those obtained by other methods.
Received: 27 January 1999 / Revised: 5 July 1999 / Accepted: 7 July 1999 相似文献
10.
To establish an electrochemical HPLC detection system which is suitable for the voltammetric characterisation of unknown
contaminants and food components at working potentials lower than –1 V, a modified flow-through cell for the use of a hanging
mercury drop electrode (HMDE) is described. The introduction of silanised glass capillaries and a new flow-channel design
provide a high HMDE lifetime, which is recommended in HPLC detection. As test system the herbicides diquat, paraquat and difenzoquat
and ethylviologen as internal standard were measured using differential pulse voltammetry (DPV) detection to improve selectivity.
Spiked water samples were analysed with voltammetric and UV-detection and results agreed well.
Received: 12 November 1998 / Revised: 21 January 1999 / Accepted: 26 January 1999 相似文献
11.
A simple computerized potentiometric titrator is described for performing automated analyses of chloride ions on solid materials
as well as the continuous determination of HCl in effluent gas streams. This versatility has been obtained by a dedicated
instrumental design, which offers easy interfacing to catalytic reactors and flexibility in software programs, including Gran’s
plot determination of end-points. The validation of the analytical methodology for quantitative determination of chloride
ions in solid matrices required the definition and the preparation of suitable reference materials of known chloride content.
Received: 8 November 1999 / Revised: 21 January 2000 / Accepted: 29 January 2000 相似文献
12.
A method has been developed for the determination of seven arsenic species in mussel tissues by liquid chromatography-hydride generation-UV photo-oxidation and detection by inductively coupled plasma mass spectrometry. In order to determine the different species, two ion-exchange columns (anionic and cationic) were used with phosphate and nitric acid/ammonium nitrate as mobile phases, respectively. The optimisation of the conditions for separation, photo-oxidation and hydride generation is described. For each of these species, the limits of detection and repeatability are reported with the entire system coupling. This system was applied to the analysis of certified reference material (CRM 278) and mussels collected from Barcelona harbour. Extractions were achieved in methanol/water (1:1) using low-power focused microwaves as leaching process. As expected, arsenobetaine was the main compound extracted from both materials; the typical concentrations found were between 1 and 7 mg kg(-1). Other organoarsenical compounds, probably arsenosugars, were extracted in a concentration range of 0.3-1.5 mg kg(-1) in both cases. Amounts of dimethylarsinate (DMA) were found to be significant in the CRM 278, but very low in mussels from Barcelona harbour. The low limits of detection of the coupled system allow us to quantify low contents of other species (As(V), arsenocholine and monomethylarsonate (MMA)). 相似文献
13.
A sensitive kinetic spectrophotometric method has been developed for the determination of Se(IV) over the range of 45 to
4000 ng in 10 mL of solution. The method is based on the catalytic effect of Se(IV) on the reduction reaction of bromate by
hydrazinium dichloride, with subsequent reaction of Ponceau S with products of the above reaction (chlorine and bromine),
causing color changing of Ponceau S. Method development includes optimization of time interval for measurement of slope, pH,
reagents concentration, and temperature. The optimized conditions yielded a theoretical detection limit of 33 ng/?10 mL of
solution of Se(IV). The interfering effects were studied and removed. The method was applied to the determination of selenium
in spiked water, Kjeldahl tablet, selenium tablet, and shampoo. Vanadium(V) has an inhibition effect on the catalyzed reaction
of bromate and hydrazine by selenium. Using this effect, V(V) can be determined in the range of 70 to 2500 ng in 10 mL of
solution. The optimization procedure includes pH and selenium concentration. An extraction method was used for interference
removal. The method was applied to the determination of vanadium in petroleum.
Received: 20 October 1998 / Revised: 17 April 1999 / Accepted: 3 June 1999 相似文献
14.
Shu-Sheng Zhang K. Jiao Hong-Yuan Chen Cheng-Liang Zhang Zuo-Fang Zhang 《Fresenius' Journal of Analytical Chemistry》1999,364(8):758-762
An improved ELISA for the determination of tobacco mosaic virus (TMV) with linear sweep voltammetry based on a new system
of p-aminophenol (PAP)- H2O2- horseradish peroxidase (HRP) has been developed. The enzymatic product 3-[(4-hydroxyphenyl)amino]-4-(2-amino-5-hydroxyphenyl)-6-[(4-hydroxyphenyl)imino]-2,4-cyclohexadiene-1-one,
produced from HRP catalyzing the oxidation of PAP with H2O2, yields a sensitive linear sweep voltammetric response at a potential of –0.45 V (vs. SCE) in Britton-Robinson (BR) buffer
solution. By using this voltammetric peak, HRP can be measured with a detection limit of 0.4 mU/L and a linear range of 1.0
∼ 1.0 × 102 mU/ L. The detection limit for the clarified TMV is 4.0 ng/mL and the highest dilution ratio detected for the infected leaf
sap is 1 : 3.9 × 106. The processes of the enzyme-catalyzed reaction and the electro-reduction of the product of the enzyme-catalyzed reaction
have been investigated.
Received: 17 November 1998 / Revised: 17 March 1999 / Accepted: 20 March 1999 相似文献
15.
I. Kuselman 《Accreditation and quality assurance》2000,5(3):100-103
An approach to assess the permissible ranges for results of replicate determinations using uncertainty calculation is discussed.
The approach is based on the known range distribution for normalized "range/standard deviation" values, which is equivalent
to the distribution of the range for normalized results of replicate determinations having an average of 0 and a standard
deviation of 1. It is shown that the permissible ranges can be assessed using tabulated percentiles of this distribution and
calculated values of the determination (analysis) standard uncertainty. When the standard uncertainty calculation is performed
before the analytical method validation, the permissible ranges can be predicted. As an example, the range is predicted for
a new pH-metric method for acid number determination without titration in petroleum oils (basic, white and transformer). The
results of the prediction are in good conformity with the experimental data.
Received: 23 May 1999 · Accepted: 14 November 1999 相似文献
16.
A. A. Ensafi H. Rahimi Mansour K. Zarei 《Fresenius' Journal of Analytical Chemistry》1999,363(7):646-650
A novel method for the determination of cobalt(II) by stripping voltammetry is described. It involves an adsorptive accumulation
of the cobalt(II)-2-aminocyclopentene-1-dithiocarboxylic acid complex on a hanging mercury drop electrode, followed by a stripping
voltammetric measurement of the catalytic reduction current of the complex at –1.4 V at pH = 9 (vs. Ag/AgCl). The effects
of various experimental parameters on the catalytic current were investigated. An accumulation time of 60 s results in a low
experimental limit of detection of 0.1 ng/mL of Co(II), and 0.50 to 40.0 ng/mL of cobalt can be determined. The relative
standard deviation at 0.50 ng/mL is 2.8%. Possible interferences from co-existing ions were also investigated.
Received: 17 August 1998 / Revised: 16 November 1998 / Accepted: 20 November 1998 相似文献
17.
A novel method for the determination of cobalt(II) by stripping voltammetry is described. It involves an adsorptive accumulation
of the cobalt(II)-2-aminocyclopentene-1-dithiocarboxylic acid complex on a hanging mercury drop electrode, followed by a stripping
voltammetric measurement of the catalytic reduction current of the complex at –1.4 V at pH = 9 (vs. Ag/AgCl). The effects
of various experimental parameters on the catalytic current were investigated. An accumulation time of 60 s results in a low
experimental limit of detection of 0.1 ng/mL of Co(II), and 0.50 to 40.0 ng/mL of cobalt can be determined. The relative
standard deviation at 0.50 ng/mL is 2.8%. Possible interferences from co-existing ions were also investigated.
Received: 17 August 1998 / Revised: 16 November 1998 / Accepted: 20 November 1998 相似文献
18.
R. Nowka I. L. Marr T. M. Ansari H. Müller 《Analytical and bioanalytical chemistry》1999,364(6):533-540
Solid sampling graphite furnace atomic absorption spectroscopy (SS-GFAAS) has been used for the determination of traces of
heavy metals (Cd, Pb, Cu, Cr, Ni, V and As) in barytes over a wide concentration range, e.g. Cd from 0.023 to 27.0 μg/g and
Pb from 1.54 to 3509 μg/g.The necessity of determining heavy metals in commercial barytes (naturally occurring barium sulfate),
a mineral important to the oil industry because of its use in drilling muds, is discussed. The problems presented by the analysis
of this difficult matrix are elegantly solved by using SS-GFAAS for the direct determination of heavy metals. A high-performance
graphite furnace AAS with D2-background correction system and a transversely heated graphite atomizer was used for the investigations. The spectrometer
was combined with a mechanical sampling module and an ultramicrobalance. The transfer of solid samples (sample weights 0.031–0.686
mg) into the atomizer was carried out by using an optimized graphite platform as the sample carrier. Calibration curve techniques
and standard addition methods were employed using external standards (CRMs). Problems associated with signal deformations
like multiple peaks, tailing or shoulders are also discussed and possibilities to solve the problems are given. The influence
of the homogeneity of solid samples on the precision and accuracy are shown in a real example. The results obtained by SS-GFAAS
were compared with results by other methods like X-ray fluorescence spectroscopy (XRF) and flame AAS after aqua regia microwave extraction. This study has demonstrated that SS-GFAAS is a very powerful and easy-to-use method for quick and accurate
analysis of barytes.
Received: 9 November 1998 / Revised: 29 January 1999 / Accepted: 2 February 1999 相似文献
19.
A method for the determination of sixteen elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, Sn, V, Zn) in seafood
by dynamic reaction cell inductively coupled plasma mass spectrometry (ICP–DRC–MS) is presented. A preliminary study of polyatomic
interferences was carried out in relation to the chemical composition of marine organisms belonging to different taxa. Acid
effects and other matrix effects in marine organisms submitted to closed-vessel microwave digestion were investigated as well.
Ammonia was the reactive gas used in the DRC to remove polyatomic ions interfering with 27Al, 52Cr, 56Fe and 51V. Optimal conditions for the simultaneous determination of analytes were identified in order to develop a fast multielement
method. A suite of real samples (mussels and various fish species) were used during method development along with three certified
reference materials: BCR CRM 278R (mussel tissue), BCR CRM 422 (cod muscle) and DORM-2 (dogfish muscle). The proposed analytical
approach can be used in conjunction with suitable chemometric procedures to address quality and safety issues in aquaculture
and fisheries. As an example, a case study is described in which mussels from three farming sites in the Venice Lagoon were
distinguished by multivariate analysis of element fingerprints.
相似文献
20.
R. Nowka I. L. Marr T. M. Ansari H. Müller 《Fresenius' Journal of Analytical Chemistry》1999,364(6):533-540
Solid sampling graphite furnace atomic absorption spectroscopy (SS-GFAAS) has been used for the determination of traces of
heavy metals (Cd, Pb, Cu, Cr, Ni, V and As) in barytes over a wide concentration range, e.g. Cd from 0.023 to 27.0 μg/g and
Pb from 1.54 to 3509 μg/g.The necessity of determining heavy metals in commercial barytes (naturally occurring barium sulfate),
a mineral important to the oil industry because of its use in drilling muds, is discussed. The problems presented by the analysis
of this difficult matrix are elegantly solved by using SS-GFAAS for the direct determination of heavy metals. A high-performance
graphite furnace AAS with D2-background correction system and a transversely heated graphite atomizer was used for the investigations. The spectrometer
was combined with a mechanical sampling module and an ultramicrobalance. The transfer of solid samples (sample weights 0.031–0.686
mg) into the atomizer was carried out by using an optimized graphite platform as the sample carrier. Calibration curve techniques
and standard addition methods were employed using external standards (CRMs). Problems associated with signal deformations
like multiple peaks, tailing or shoulders are also discussed and possibilities to solve the problems are given. The influence
of the homogeneity of solid samples on the precision and accuracy are shown in a real example. The results obtained by SS-GFAAS
were compared with results by other methods like X-ray fluorescence spectroscopy (XRF) and flame AAS after aqua regia microwave extraction. This study has demonstrated that SS-GFAAS is a very powerful and easy-to-use method for quick and accurate
analysis of barytes.
Received: 9 November 1998 / Revised: 29 January 1999 / Accepted: 2 February 1999 相似文献