共查询到20条相似文献,搜索用时 31 毫秒
1.
F. Lagarde M. B. Amran M. J. F. Leroy C. Demesmay M. Ollé A. Lamotte H. Muntau P. Michel P. Thomas S. Caroli E. Larsen P. Bonner G. Rauret M. Foulkes A. Howard B. Griepink E. A. Maier 《Fresenius' Journal of Analytical Chemistry》1999,363(1):18-22
Tuna fishes were collected in the Straits of Messina (Italy), were dissected and dorsal muscles minced, freeze-dried, ground
and sieved. The obtained powder was stabilised by γ-irradiation and filled into brown glass bottles. The homogeneity and stability
at +20 °C and +40 °C were verified with regards to the total arsenic, dimethylarsinic acid and arsenobetaine contents. Ten
laboratories participated in the certification study. All participants had demonstrated beforehand their ability to produce
accurate results for the As speciation in fish tissue. The certified values are: total arsenic (4.8 ± 0.3) mg/kg, arsenobetaine
(52 ± 3) μmol/kg, dimethylarsinic acid (2.0 ± 0.3) μmol/kg. The material is available from the BCR since early 1998.
Received: 31 March 1998 / Revised: 20 July 1998 / Accepted: 25 July 1998 相似文献
2.
R. Haas Torsten C. Schmidt Klaus Steinbach Eberhard von L?w 《Fresenius' Journal of Analytical Chemistry》1998,361(3):313-318
Urinary arsenic speciation is considered to be an effective procedure to differentiate between toxic inorganic and less toxic
organic arsenic exposure. The aim of the present work was to develop a new method for the simultaneous determination of the
main arsenic species so far detected in urine: arsenite (As(III)), arsenate (As(V)), methylarsonic acid (MA), dimethylarsinic
acid (DMA), and arsenobetaine (AsB). The method is based on anion exchange HPLC coupled on-line to an inductively coupled
plasma mass spectrometer (ICP-MS) for element specific detection. Experimental parameters, such as column type and composition
of the mobile phases were optimized in order to get best separation, little matrix interferences, lowest detection limits,
and short total times of analyses. Best chromatographic conditions were obtained by using a Dionex AS14 anion exchange column
and a gradient elution with tetramethylammonium hydroxide and ammonium carbonate as eluting compounds. The detection limits
(3 σ) were found to be in the sub μg L–1 range. The method was applied to analyze different urine samples from persons with and without consumption of seafood. To
avoid significant matrix influences, samples (24 h urine) had to be diluted 1 : 5 with water and were filtered through a 0.45
μm filter prior to analyses. Special attention was focused on the validation of the method according to the regulations of
the “Deutsche Forschungsgemeinschaft” (DFG) for the analyses of hazardous substances in biological materials.
Received: 22 December 1997 / Revised: 18 February 1998 / Accepted: 22 February 1998 相似文献
3.
A. Martín-Esteban P. Fernández C. Cámara G. N. Kramer E. A. Maier 《Fresenius' Journal of Analytical Chemistry》1999,363(7):632-640
The preparation of a certified reference material of polar pesticides in freeze-dried water is described. The pesticides
selected were atrazine, simazine, carbaryl, propanil, linuron, fenamiphos and permethrin which were added to 6000 litres of
tap water at 50–80 μg · L–1 (200–320 μg · L–1 for permethrin) level in presence of NaCl (2.5 g · L–1) prior lyophilization. After the freeze-drying process the residue was rehomogenized, filled into amber glass bottles and
stored at –20 °C, +4 °C and +20 °C. All pesticides were determined by HPLC/diode array detector, except permethrin which was
determined by GC/ECD. The results obtained for atrazine, simazine, carbaryl, propanil, linuron and fenamiphos showed no within-
or between-bottle inhomogeneity, however the material was non-homogeneous for permethrin and therefore this was withdrawn
from further studies. With respect to the stability for over one year, all pesticides were stable at –20 °C. At +4 °C all
pesticides were stable for at least 9 months and at +20 °C the stability was demonstrated only during the first month of storage.
The content (mass fractions) of atrazine, simazine, carbaryl, propanil and linuron in freeze-dried water (CRM 606) was certified
by an interlaboratory testing and a certification campaign.
Received: 7 September 1998 / Revised: 13 November 1998 / Accepted: 21 November 1998 相似文献
4.
Jaw-Cherng Hsu Chin-Hung Chang C.-Y. Liu 《Analytical and bioanalytical chemistry》1998,362(6):514-521
A silica based sorbent with an anion complexone polymer coating, [24]ane-N6 macrocycle, was prepared. The chelation properties of this material were investigated by elemental analysis, infrared spectra
and Voige’s method. The polymer-coated silica column (25– 40 μm, 100 × 4.6 mm i.d.) was employed for trace metal analyses.
Oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid and acetic acid were used as mobile phases. Their retention
characteristics were elucidated. Oxalic acid was found to be the most effective eluent. With a mobile phase consisting of
oxalic acid (25 mM) and sodium nitrate (25 mM) at pH 4.2, the separation of copper(II), cadmium(II), cobalt(II) and zinc(II)
in sea water could be achieved. The identification of metal ions was performed at 510 nm using 4(2-pyridylazo)resorcinol (1
× 10–4 M) as post column reagent. The limits of detection were 5 × 10–7 M, 1 × 10–5 M, 3 × 10–5 M and 2 × 10–6 M for copper(II), cadmium(II), cobalt(II) and zinc(II) based on three times the standard deviation of the response for the
lowest concentration (n = 5) in the chromatogram with a sample volume of 50 μL. For evaluation of data reliability, oyster
tissue (NIST SRM 1566 a) was studied with the proposed system.
Received: 9 February 1998 / Revised: 15 May 1998 / Accepted: 16 June 1998 相似文献
5.
R. Mu?oz Olivas Philippe Quevauviller O. F. X. Donard 《Fresenius' Journal of Analytical Chemistry》1998,360(5):512-519
Long term stability of organic selenium compounds (selenocystine, selenomethionine, trimethylselenonium ion) has been studied
over a one year period for 2 analyte concentrations: 25 and 150 μg/L Se, at pH 4.5 in the dark, under different storage conditions:
temperature of –20°C, 4°C, 20°C, 40°C; in Pyrex, Teflon, or polyethylene containers; in an aqueous matrix or in the presence
of a chromatographic counter ion (pentyl sulfonate at 10–4 mol/L concentration). Light effects have also been tested. The stability of the selenium species was monitored by HPLC-ICP/MS.
Storage conditions can drastically alter the stability of organic selenium species. Organoselenium compounds were shown to
be stable in the dark over a one year period in an aqueous matrix at pH 4.5 in Pyrex containers at both 4°C and 20°C. Pyrex
vials exposed to natural sunlight at room temperature resulted in a steady decrease of the selenoamino acid concentration.
Teflon containers caused losses of less than 25% at both 4° C and 20° C in the dark. However, polyethylene vials presented,
at all temperatures tested, a rapid decrease of the TMSe+ concentration. The stability of the Se species studied did not show significant differences between 4° C and 20° C in any
container material used. Storage of solutions at 40° C led to slight differences between the Pyrex and Teflon containers.
However, polyethylene presented a drastic decrease of the three species over time at this higher temperature. Solutions frozen
at –20° C in polyethylene vials did not stabilize the TMSe+ signal. Finally, concentrations and matrices of the samples did not significantly affect the stability of the species.
Received: 15 July 1996 / Revised: 14 July 1997 / Accepted: 18 July 1997 相似文献
6.
J. Feldmann Katie John Paramee Pengprecha 《Analytical and bioanalytical chemistry》2000,368(1):116-121
Cation exchange and anion exchange liquid chromatography were coupled to an ICP-MS and optimised for the separation of 13
different arsenic species in body fluids (arsenite, arsenate, dimethylarsinic acid (DMAA), monomethylarsonic acid (MMAA),
trimethylarsine oxide (TMAO), tetramethylarsonium ion (TMA), arsenobetaine (AsB), arsenocholine (AsC), dimethylarsinoyl ethanol
(DMAE) and four common dimethylarsinoylribosides (arsenosugars). The arsenic species were determined in seaweed extracts and
in the urine and blood serum of seaweed-eating sheep from Northern Scotland. The sheep eat 2–4 kg of seaweed daily which is
washed ashore on the most northern Island of Orkney. The urine, blood and wool of 20 North Ronaldsay sheep and kidney, liver
and muscle from 11 sheep were sampled and analysed for their arsenic species. In addition five Dorset Finn sheep, which lived
entirely on grass, were used as a control group. The sheep have a body burden of approximately 45–90 mg arsenic daily. Since
the metabolism of arsenic species varies with the arsenite and arsenate being the most toxic, and organoarsenic compounds
such as arsenobetaine the least toxic compounds, the determination of the arsenic species in the diet and their body fluids
are important. The major arsenic species in their diet are arsenoribosides. The major metabolite excreted into urine and blood
is DMAA (95 ± 4.1%) with minor amounts of MMAA, riboside X, TMA and an unidentified species. The occurrence of MMAA is assumed
to be a precursor of the exposure to inorganic arsenic, since demethylation of dimethylated or trimethylated organoarsenic
compounds is not known (max. MMAA concentration 259 μg/L). The concentrations in the urine (3179 ± 2667 μg/L) and blood (44
± 19 μg/kg) are at least two orders of magnitude higher than the level of arsenic in the urine of the control sheep or literature
levels of blood for the unexposed sheep. The tissue samples (liver: 292 ± 99 μg/kg, kidney: 565 ± 193 μg/kg, muscle: 680 ±
224 μg/kg) and wool samples (10 470 ± 5690 μg/kg) show elevated levels which are also 100 times higher than the levels for
the unexposed sheep.
Received: 29 February 2000 / Revised: 26 April 2000 / Accepted: 1 May 2000 相似文献
7.
Debasish Banerjee Bhim C. Mondal Debasis Das Arabinda K. Das 《Mikrochimica acta》2003,141(3-4):107-113
A new resin has been synthesized by functionalisation of polystyrene-divinylbenzene (8%) with imidazole 4,5-dicarboxylic
acid through –N=N– bonding. The resulting resin has been characterised by elemental analysis, thermogravimetric analysis,
infrared spectroscopy, hydrogen ion capacity and metal ion capacity. The speciation study of vanadium has been studied by
using this resin and the maximum exchange capacity was found to be 0.45 mmol g−1 for V4+ and that for V5+ was 1.57 mmol g−1 at pH 3 for both. The eluents malonic acid and sodium hydroxide have been used for the selective separation of vanadium(IV)
and vanadium(V) species respectively. The effects of diverse ions on the sorption and recovery of each species have been studied.
Finally, the developed method has been applied for the speciation and determination of these two species in natural water
samples.
Correspondence: Department of Chemistry, The University of Burdwan, Burdwan, India. e-mail: akdas100@yahoo.com
Received December 20, 2001; accepted October 11, 2002 相似文献
8.
Five arsenic species, trimethylarsine oxide, dimethylarsenic acid, monomethylarsonic acid, arsenobetaine and sodium arsenite, in urine were analysed by inductively coupled plasma mass spectrometry with ion chromatography (IC ICP MS). Since the toxicities of different arsenic compounds are different, speciation of arsenic compounds is very important in the investigation of metabolisms. In this paper, we applied ion chromatography (IC) as a separation device and inductively coupled plasma mass spectrometry (ICP MS) as a detection device. For separation of the five arsenic compounds, an anion-exchange column and, as mobile phase, tartaric acid were used. The eluent from the IC column was introduced directly into the nebulizer of the ICP MS and analysed at 75 amu. Detection limits were from 4 to 9 pg as arsenic. 相似文献
9.
Application of ion chromatography for the investigation of the anionic and cationic composition in high-purity water production 总被引:2,自引:0,他引:2
V. D. Nguyen H. Neumeister G. Subklew 《Fresenius' Journal of Analytical Chemistry》1999,363(8):783-788
A suitable and sensitive ion chromatographic measuring system for determining the main components at nanogram to milligram
per liter levels in water samples from the electrodeionization process is presented. A modified Dionex system offers the possibility
for the determination of anions and cations in the samples at ng/L, μg/L and mg/L levels. The ng/L level of anions and cations
in 20–130 mL high-purity water can be analyzed immediately after preconcentration on appropriate exchange columns. The mg/L
level samples are successfully determined by use of an auto-sampler. The quantification of each ion is achieved using the
suppressor technique and a conductivity detector. Samples are taken from 5 steps of the electrodeionization process and stored
in pre-cleaned FEP (fluorinated ethylene propylene) at 7 °C in darkness prior to the determination of chloride, nitrate, sulfate,
carbonate, sodium, ammonium, potassium, calcium and magnesium. Eluents, ultrapure water and samples for the determination
of carbonate were passed through special glass containers and flushed with helium gas to avoid the effect of atmospheric carbon
dioxide. Results of the investigation of the cationic and anionic composition in water samples within the electrodeionization
process are presented and discussed.
Received: 12 October 1998 / Revised: 16 December 1998 / Accepted: 19 December 1998 相似文献
10.
Longquan Li Ping Yan Wenzhong Gao Yadong Li 《Analytical and bioanalytical chemistry》1999,363(3):317-319
Emulsion liquid membranes (ELM) consisting of L113A (surfactant), liquid paraffin (stabilizer) and kerosene (solvent), with
HCl solution acting as the external phase and KOH solution acting as the internal phase, were applied to the prior separation
of arsenic(III) and arsenic(V) with subsequent spectrophotometric determination by AgDDTC. The effect of various parameters
on the recovery of arsenic(III) were investigated. 8 mol/L HCl was required for 95% As(III) recovery. After reduction of As(V)
to As(III) with sufficient KI, total arsenic could be determined. The RSD of As(III) and As(total) were both less than 3%.
The procedure was applied to aqueous samples with a recovery of 93.5%–101%.
Received: 22 March 1998 / Revised: 12 September 1998 / Accepted: 17 September 1998 相似文献
11.
Longquan Li Ping Yan Wenzhong Gao Yadong Li 《Fresenius' Journal of Analytical Chemistry》1999,363(3):317-319
Emulsion liquid membranes (ELM) consisting of L113A (surfactant), liquid paraffin (stabilizer) and kerosene (solvent), with
HCl solution acting as the external phase and KOH solution acting as the internal phase, were applied to the prior separation
of arsenic(III) and arsenic(V) with subsequent spectrophotometric determination by AgDDTC. The effect of various parameters
on the recovery of arsenic(III) were investigated. 8 mol/L HCl was required for 95% As(III) recovery. After reduction of As(V)
to As(III) with sufficient KI, total arsenic could be determined. The RSD of As(III) and As(total) were both less than 3%.
The procedure was applied to aqueous samples with a recovery of 93.5%–101%.
Received: 22 March 1998 / Revised: 12 September 1998 / Accepted: 17 September 1998 相似文献
12.
Two-phase systems consisting of a polymer rich phase and polymer depleted phase, where the polymer is either ethyl(hydroxy
ethyl)cellulose (EHEC) or Ucon (a random copolymer of ethylene oxide and propylene oxide), have been studied. Both of these
polymers can be separated from an aqueous solution by either temperature increase or addition of cosolutes. The polymers are
thermoseparating and phase separate in water solutions at the cloud point temperature. Two types of EHEC have been studied:
one with a cloud point at 60 °C and the other at 37 °C. The Ucon polymer used in this study has a cloud point at 50 °C. Ternary
phase diagrams of polymer/water/cosolute systems have been investigated. When a strongly hydrophilic or hydrophobic cosolute
is added to an EHEC- or Ucon–water solution, a phase separation occurs already at, or below, room temperature. As cosolutes,
hydrophobic molecules like phenol, butyric and propionic acid, and hydrophilic molecules like glycine, ammonium acetate, sodium
carboxylates (acetate to valerate), were studied. The polymer rich phase formed when mixing polymer, water and cosolute was
strongly enriched or depleted with hydrophobic or hydrophilic cosolutes, respectively. The two phase region increased for
propionic acid, butyric acid and phenol as a result of increased cosolute hydrophobicity. The opposite occurred in the series
sodium acetate, sodium butyrate and sodium valerate. The effect of temperature on the phase behaviour has also been investigated.
Model calculations based on Flory–Huggins theory of polymer solutions are presented, in form of a phase diagram, which semiquantitatively
reproduce some experimental results.
Received: 5 July 1996 Accepted: 4 November 1996 相似文献
13.
A. Lopez-Molinero J. R. Castillo Pilar Chamorro Pascual Asuncion Callizo 《Mikrochimica acta》1999,131(3-4):225-230
The generation of volatile species of As(III) as a means to introduce arsenic into a flame atomic absorption spectrometer
has been studied. The method is based on the reaction between As(III) and chloride ions in sulphuric acid medium. The reaction
is performed in a discontinuous or batch mode. With this method 130 μl of a solution containing 17.5% (w/v) sodium chloride
and As(III) are injected by a 500 ml.min−1 N2 carrier gas flow into 1 ml of concentrated sulphuric acid. The gaseous compounds generated are introduced into the spectrometer
through the nebulizer and As is determined.
Received October 3, 1998. Revision January 6, 1999. 相似文献
14.
Separation of organic and inorganic arsenic species by capillary zone electrophoresis 总被引:1,自引:0,他引:1
Summary Capillary zone electrophoresis has been used to separate arsenite, arsenate, dimethylarsinic acid, and phenyl-,p-aminophenyl-, ando-aminophenylarsinic acids. Identification and quantification of the arsenic species at mg L−1 levels was possible by use of direct UV detection at 200 nm. The relative standard deviation (n=7) ranged from 0.97 to 1.52% for migration times and from 2.08 to 4.31% for peak areas. A method for rapid separation of
inorganic arsenic species was also developed; by use of this method arsenite and arsenate could be separated within 2 min.
Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999 相似文献
15.
An analytical characterization of microbiological oxidation and reduction of sulfur anions has been performed with dual ion
chromatography. The apparatus consisted of two chromatographic lines combined by a sample injection valve that allows the
simultaneous introduction of a sample solution to both systems. With system 1 non-suppressed conductivity detection of sulfite
and sulfate after separation in phthalate eluent was performed. For sulfide, thiosulfate and thiocyanate amperometric detection
using a carbonate eluent was carried out on system 2. Parallel runs were possible for these species which could not be separated
with one system. Optimizing separation and detection, limits of quantification of 0.02–0.3 mg/L could be obtained. The on-line
coupling of a reaction vial to the injection valve was used to investigate the bacterial conversions, because the samples
could be taken without contamination and air introduction. Thiosulfate was detected as a metabolite in both sulfur reduction
and oxidation. Capillary electrophoresis with conductivity detection was applied as a complimentary technique for monitoring
the bacterial sulfur oxidation. The results showed good correlation to the concentration values obtained by ion chromatography.
Received: 14 May 1999 / Revised: 7 July 1999 / Accepted: 10 July 1999 相似文献
16.
Narachum V. Sreekumar Nellikalaya G. Bhat Badiadka Narayana Ronald A. Nazareth Prashant Hegde Busnur R. Manjunatha 《Mikrochimica acta》2003,141(1-2):29-33
A simple, rapid and accurate complexometric method is proposed for the determination of titanium(IV) where sodium potassium
tartrate or ascorbic acid were used as masking agents. In the presence of diverse metal ions, titanium is first complexed
with excess of EDTA and surplus EDTA is then titrated at pH 5–6 with zinc sulfate, xylenol orange being used as indicator.
An excess of 5% aqueous sodium potassium tartrate is then added to displace the complexed EDTA from the Ti-EDTA complex quantitatively,
which is titrated with zinc sulfate. Also, ascorbic acid may be used as the releasing agent. The methods work well in the
range 1–53 mg of Ti(IV) for sodium potassium tartrate with relative errors ± 0.28% and standard deviations ≤ 0.16 mg. For
ascorbic acid the range is 1.00–30.00 mg of Ti(IV) with relative errors of ± 0.40% and standard deviations of ≤ 0.05 mg
Received October 9, 2001; accepted August 2, 2002 相似文献
17.
Fátima Duarte Freire C. Flávio Soares Aragão T. Flávio Accioly de Lima e Moura Fernanda Nervo Raffin 《Journal of Thermal Analysis and Calorimetry》2009,97(1):355-357
Chlorpropamide ((4-chloro-N-(propylamino)-carbonyl)-benzenesulfonamide) belongs to compounds having sulfonylurea group and is widely used as an oral
antidiabetic agent. In this work differential scanning calorimetry (DSC) was used during pre-formulation of chlorpropamide
tablets to determine the drug-excipients compatibility. The DSC curves of chlorpropamide and binary mixtures with excipients
(sodium croscarmellose, sodium lauryl sulfate, microcrystalline cellulose, magnesium stearate and calcium carbonate) showed
that chlorpropamide exhibited interaction with magnesium stearate and sodium lauryl sulfate. The binary mixtures of chlorpropamide–magnesium
stearate presented a single endothermic process at 96–108 °C and chlorpropamide–sodium lauryl sulfate showed a wide endotherm
at 99–120 °C. 相似文献
18.
S. Nagadome A. Yamauchi K. Miyashita H. Igimi G. Sugihara 《Colloid and polymer science》1998,276(1):59-65
The transport behavior of bile salts (BSs) solubilizing cholesterol (Ch) or none across an artificial membrane was investigated
for sodium salts of deoxycholic acid (NaDC), chenodeoxycholic acid (NaCDC), ursodeoxycholic acid (NaUDC) and cholic acid (NaC)
in tetraborate–carbonate buffer solution at pH 10.0 and 37 °C. The study demonstrated that the surfactant properties such
as critical micellization concentration (CMC) and micellar size or diffusion coefficient were determinable from the flux or
permeability measurements. The comparison among the respective pure systems of BSs led to a conclusion that the micellar size
was in the order of NaDC>NaCDC>NaUDC>NaC and determined CMC values were in agreement with those in literature.
The magnitude of solubilizing power (capacity) of BS for Ch was found to decrease in the order of NaDC>NaCDC>NaC>NaUDC; this
order is in accordance with that of the empirical hydrophobicity index. The hydrodynamic radii for the singly dispersed species
and the micellar species of the respective BSs and of Ch-solubilizing micelles were estimated from the permeability data;
the radii of the Ch-solubilizing micelles are approximately 12–15 Å and interestingly, smaller than those of the respective
BS alone micelles ranging from 14 to 22 Å.
Received: 15 April 1997 Accepted: 25 July 1997 相似文献
19.
Arsenic speciation analysis in marine samples was performed using ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP‐MS) detection. The separation of eight arsenic species, viz. arsenite, monomethyl arsonic acid, dimethylarsinic acid, arsenate, arsenobetaine, tetramethylarsine oxide, arsenocholine and tetramethylarsonium ion was achieved on a Dionex AS4A (weaker anion exchange column) by using a nitric acid pH gradient eluent (pH 3.3 to 1.3). The entire separation was accomplished in 12 min. The detection limits for the eight arsenic species by IC–ICP‐MS were in the range 0.03–1.6 µ g l?1, based on 3σ of the blank response (n = 6). The repeatability and day‐to‐day reproducibility were calculated to be less than 10% (residual standard deviation) for all eight species. The method was validated by analyzing a certified reference material (DORM‐2, dogfish muscle) and then successfully applied to several marine samples, e.g. oyster, fish muscle, shrimp and marine algae. The low power microwave digestion was employed for the extraction of arsenic from seafood products. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
20.
Interactions of sodium dodecyl sulfate with acrylamide –N-isopropylacrylamide) statistical copolymer
Poly(N-isopropylacrylamide) (PNIPAM) precipitates out of water around 32 °C. This critical temperature is raised when hydrophilic
acrylamide sequences are present on the polymer chain. We have used neutron scattering to study the structural properties
of a statistical copolymer containing acrylamide and N-isopropylacrylamide segments at different temperatures and its interactions with an anionic surfactant, sodium dodecyl sulfate
(SDS). At low temperatures, the copolymer behaves as a swollen polymer coil. With an increase in temperature, intermolecular
attractions are observed, and close to the critical temperature of the copolymer, microphase separation is observed. Here,
the structure consists of dense nodules of hydrophobic sequences stabilized by hydrophilic sequences. In the presence of a
small amount of SDS, additional colloidal stability is observed: the nodule size is decreased. At high SDS concentration,
the copolymer is completely solubilized at all temperatures studied and the structure of the polymer–surfactant complex resembles
the “necklace” structure obtained for the homopolymer PNIPAM–SDS system.
Received: 11 November 1999 Accepted: 15 December 1999 相似文献