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1.
McCarron P Kotterman M de Boer J Rehmann N Hess P 《Analytical and bioanalytical chemistry》2007,387(7):2487-2493
The effect of γ-irradiation on concentrations of hydrophilic and lipophilic phycotoxins has been investigated by use of HPLC–UV
and LC–MS. Pure toxins in organic solvents and toxins in mussel (Mytilus edulis) tissues were irradiated at three different doses. In solution all toxin concentrations were reduced to some extent. Most
severe decreases were observed for domoic acid and yessotoxin, for which the smallest dose of irradiation led to almost complete
destruction. For pectenotoxin-2 the decrease in concentration was less severe but still continuous with increasing dose. Azaspiracid-1
and okadaic acid were the least affected in solution. In shellfish tissue the decrease in toxin concentrations was much reduced
compared with the effect in solution. After irradiation at the highest dose reductions in concentrations were between ca.
5 and 20% for the lipophilic toxins and there was no statistical difference between control and irradiated samples for azaspiracids
in tissue. Irradiation of shellfish tissues contaminated with domoic acid led to a more continuous decrease in the amount
of the toxin with increasing dose. The effect of irradiation on the viability of microbial activity in shellfish tissues was
assessed by using total viable counting techniques. Microbial activity depended on the type of shellfish and on the pretreatment
of the shellfish tissues (with or without heat treatment). As far as we are aware this is the first investigation of the effectiveness
of irradiation as a technique for stabilising tissue reference materials for determination of phycotoxins. Our results suggest
that this technique is not effective for materials containing domoic acid. It does, however, merit further investigation as
a stabilisation procedure for preparation of shellfish tissue materials for some lipophilic toxins, in particular azaspiracids.
Chemical structures of the toxins investigated in the study 相似文献
2.
Two samples of mussels (Mytilus edulis) were collected from the southwest of Ireland. One sample contained domoic acid, the other sample contained okadaic acid,
dinophysistoxin-2 and azaspiracid-1, -2 and -3. Wet and freeze-dried reference materials were prepared from each of the two
samples to test for differences in homogeneity, stability and extractability of the analytes in either condition. Wet materials
were homogenised, aliquoted and hermetically sealed under argon and subsequently frozen at −80 °C. Dry materials were similarly
homogenised but frozen in flat cakes prior to freeze-drying. After grinding, sieving and further homogenisation, the resulting
powder was aliquoted and hermetically sealed. Domoic acid materials were characterised using HPLC–UV, while LC–MS was used
for the determination of lipophilic toxins. The extractabilities of all phycotoxins studied were comparable for wet and freeze-dried
materials once a sonication step had been carried out for reconstitution of the freeze-dried materials prior to extraction.
Homogeneity was assessed through replicate analysis of the phycotoxins (n = 10), and was found to be similar for wet and freeze-dried materials, for both hydrophilic and lipophilic toxins. Water
contents were determined for both wet and freeze-dried materials, and particle size was determined for the freeze-dried materials.
Stability was evaluated isochronously over eight months at four temperatures (−20, +4, +20 and +40 °C). The freeze-dried material
containing domoic acid was stable over the whole duration at all temperatures, while in the wet material domoic acid degraded
to some extent at all temperatures except −20 °C. In freeze-dried and wet materials containing lipophilic toxins, okadaic
acid, dinophysistoxin-2, azaspiracid-1 and azaspiracid-2 were stable over the whole duration at all conditions, while concentrations
of azaspiracid-3 changed significantly in both materials at some storage temperatures.
Figure Aliquots of freeze-dried and wet mussel tissue reference materials containing the various shellfish toxins examined in the
study 相似文献
3.
Aguinaga N Campillo N Viñas P Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2008,391(3):753-758
A sensitive and solvent-free method for the determination of ten polycyclic aromatic hydrocarbons, namely, naphthalene, acenaphthylene,
acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene and chrysene, with up to four aromatic rings, in milk samples using headspace solid-phase microextraction and
gas chromatography–mass spectrometry detection has been developed. A polydimethylsiloxane–divinylbenzene fiber was chosen
and used at 75°C for 60 min. Detection limits ranging from 0.2 to 5 ng L−1 were attained at a signal-to-noise ratio of 3, depending on the compound and the milk sample under analysis. The proposed
method was applied to ten different milk samples and the presence of six of the analytes studied in a skimmed milk with vegetal
fiber sample was confirmed. The reliability of the procedure was verified by analyzing two different certified reference materials
and by recovery studies.
Figure Milk is safe, healthy food 相似文献
4.
A new approach was developed for quantitative calibration in GD-MS which can afford reliable and metrologically traceable
results for many trace elements and was exemplified for pure copper and pure iron. It can be assumed that the technique can
be further improved and applied to the analysis of other pure metals. Pressed copper and iron powder samples were used to
calibrate the glow discharge mass spectrometry applied to the analysis of pure copper and iron. The new type of glow discharge
mass spectrometer—the Element GD (Thermo Electron Corporation)—was used with a Grimm-type discharge cell for flat samples.
Two series of powder samples were prepared for each of the copper and iron matrixes. The powders were quantitatively doped
with solutions of graduated and defined concentrations of 40 or 20 analytes, respectively. The mass fractions of the analytes
in the dried and homogenized metal powder samples ranged from μg/kg levels up to 10 mg/kg levels. A special technique was
developed to press the samples and to form mechanically stable pellets with low risk of contamination. Ion beam ratios of
analyte ions to matrix ions were used as measurands. The calibration curves were determined and the linear correlation coefficients
were calculated for different intervals of the curves. The linear correlation coefficients are very satisfactory for most
of the calibration curves, which include the higher segments of mass fractions; however, they are less satisfactory for the
lower segments of the calibration curves. Nevertheless, in many cases rather acceptable and rather promising values were achieved
even for these lower segments, representing mass fractions of analytes at ultra-trace level. The comparison of the certified
values of different reference materials with the measured values based on calibrations with the pressed powder samples led
to deviations less than 30% for most of the considered examples.
相似文献
5.
Calibration possibilities and modifier use in ETV ICP OES determination of trace and minor elements in plant materials 总被引:2,自引:0,他引:2
Albena Detcheva Peter Barth Juergen Hassler 《Analytical and bioanalytical chemistry》2009,394(5):1485-1495
The possibilities for universal calibration based on multi-element aqueous standard solutions and graphite laboratory reference
materials (graphite standards) for the electrothermal vaporization inductively coupled plasma optical emission spectrometric
(ETV ICP OES) determination of Al, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, P, Pb, S, Sr, Ti, V, and Zn in plant materials were
investigated. A commercially available state-of-the-art ETV device was coupled with an Echelle ICP spectrometer equipped with
a charge-injection-device (CID) camera for spectral detection. The transition area between transport tube and ETV graphite
tube and the gas streams for inner gas, bypass gas, and modifier gas were optimized to achieve best transport efficiencies.
The influence of four gaseous modifiers (CCl4, CHCl3, CCl2F2, and C3H8) added to the inner gas was studied. Five reference materials (RM P-Alfalfa, Lucerne; NIES CRM No.9 “Sargasso”; CTA-VTL-2
Virginia Tobacco Leaves; NIST SRM 1515 Apple Leaves; IAEA-V-10 Hay Powder) were used for method validation. If certified reference
materials are not available, calibration against graphite standards or dried aqueous standard solutions is possible. Three
carbonization procedures as sample pretreatment for the plant materials were investigated.
Figure Picture of the ETV system (sample changer and graphite-tube furbace) used in this work
Presented at the European Symposium on Atomic Spectrometry (ESAS) September 28-October 1, 2008, Weimar, Germany. 相似文献
6.
Environmental analysis is a potential key application for chemical sensors owing to their inherent ability to detect analytes
on-line and in real time in distributed systems. Operating a chemosensor in a natural environment poses substantial challenges
in terms of ruggedness, long-term stability and calibration. This article highlights current trends of achieving both the
necessary selectivity and ruggedness: one way is deploying sensor arrays consisting of robust broadband sensors and extracting
information via chemometrics. If using only a single sensor is desired, molecularly imprinted polymers offer a straightforward
way for designing artificial recognition materials. Molecularly imprinted polymers can be utilized in real-life environments,
such as water and air, aiming at detecting analytes ranging from small molecules to entire cells.
Figure 相似文献
7.
Development and certification of the new NIES CRM 28: urban aerosols for the determination of multielements 总被引:1,自引:0,他引:1
Mori I Sun Z Ukachi M Nagano K McLeod CW Cox AG Nishikawa M 《Analytical and bioanalytical chemistry》2008,391(6):1997-2003
A new environmental certified reference material (CRM) for the determination of multielements in aerosol particulate matter
has been developed and certified by the National Institute for Environmental Studies (NIES), Japan, based on analyses by a
network of laboratories using a wide range of methods. The origin of the material was atmospheric particulate matter collected
on filters in a central ventilating system in a building in Beijing city centre. The homogeneity and stability of this material
were sufficient for its use as a reference material. Values for elemental mass fractions in the material were statistically
determined based on the analytical results of the participating laboratories. Eighteen certified values and 14 reference values
were obtained. The diameters, obtained from a micrographic image using image analysis software, of 99% of the particles were
less than 10 μm, demonstrating that almost all the particles in the material could be classified as particles of 10 μm or
less in aerodynamic diameter. The chemical composition and particle size distribution of this material were close to those
of an authentic aerosol collected in Beijing. NIES CRM 28 is appropriate for use in analytical quality control and in the
evaluation of methods used in the analysis of aerosols, particularly those collected in urban environments in northeast Asia
Figure New NIES CRM 28 Urban Aerosols and photo micrograph of the material 相似文献
8.
Heike Traub Markus W?lle Joachim Koch Ulrich Panne Ralf Matschat Heinrich Kipphardt Detlef Günther 《Analytical and bioanalytical chemistry》2009,395(5):1471-1480
Solution-doped metal powder pellets as well as aspirated liquids were used as calibration samples to analyze pure copper and
zinc certified reference materials (CRMs) by femtosecond laser ablation ICP-MS. It was demonstrated that calibration by copper
pellets resulted in relative deviations up to 20%, whereas fs-LA-ICP-MS among copper-based CRMs led to inaccuracies in the
same range unless nominal mass fractions were chosen to be <3 mg/kg. Calibration by zinc pellets generally provided better
accuracy. Depending on the analyte considered, deviations below 10% were obtained even for mass fractions close to the limit
of quantification. Our data, therefore, indicate solution-doped metal powder pellets to be suitable as calibration samples
for fs-LA-ICP-MS of metals. Furthermore, the utilization of liquid standards for calibration was found to result in stronger
deviations of up to 50% for both copper and zinc samples which, in addition, turned out to be dependent on the plasma conditions.
相似文献
9.
Shakhashiro A Gondin da Fonseca Azeredo AM Sansone U Fajgelj A 《Analytical and bioanalytical chemistry》2007,387(7):2509-2515
The IAEA Reference Materials Group of the Chemistry Unit, Agency’s Laboratories Seibersdorf, has developed and optimized a
procedure for spiking some environmental matrices with gamma-emitting radionuclides. This paper describes the spiking procedure,
homogeneity testing of the spiked material, and assignment of property values and their associated uncertainties for the radionuclides
54Mn, 65Zn, 60Co, 109Cd, 134Cs, 137Cs, 210Pb, and 241Am. This procedure has already been successfully used in an IAEA proficiency test on the determination of 137Cs and 210Pb in spiked soil and has been found to be appropriate for production of soil materials for proficiency testing and internal
quality control samples. The main advantage of this procedure is a low uncertainty arising from heterogeneity, which was found
to be less than 1.2% for all the analytes studied.
相似文献
10.
Digital bioanalysis 总被引:3,自引:1,他引:2
Digital microfluidics has recently emerged as a new paradigm in the world of lab-on-a-chip technology. A wide variety of bioanalyses
have been successfully implemented in this format. This paper reviews the various techniques that have been adapted to digital
microfluidic systems, and the current state of the field.
Figure A multiplexed digital microfluidic device. Six analytical platforms are wired in series, allowing multiple independent analyses
to be performed simultaneously from a single set of controls. 相似文献
11.
Karin Hoffmann-Sommergruber E. N. Clare Mills 《Analytical and bioanalytical chemistry》2009,395(1):25-35
A large number of food allergens able to induce allergic symptoms in predisposed individuals, including severe, even life-threatening
reactions, have been identified and characterized. However, proteins able to cause such IgE-mediated reactions can be assigned
to only a limited number of protein families. Detailed knowledge about the characteristics of food allergens, their 3D structures,
biological activity and stability, will help to improve diagnosis of food allergy, avoid unnecessary exclusion diets and assess
the risk of cross-reactive allergies to other food sources. This review is dedicated to summarizing current knowledge about
the most important food allergen protein families and to presenting data from the EuroPrevall allergen library, a proof-of-concept
collection of highly purified, characterized and authenticated food allergens from animal and plant food sources to facilitate
improved diagnosis of food allergies.
Relevant food allergen sources 相似文献
12.
Sulfur has been detected in a spectral window (around 868 nm) previously unexplored by laser-induced breakdown spectrometry
(LIBS), using an ablation laser with an ultraviolet wavelength, a gated detector, and inert ambient gas at a low, controlled
pressure. This spectral window enables new-generation gated iCCD cameras to be used, which have adequate quantum efficiencies
up to 900 nm. Application of our technique can substantially improve signal strength and thus extends the ability of LIBS
to detect many nonmetallic elements.
相似文献
13.
Guevara-Riba A Sahuquillo A López-Sánchez JF Rubio R 《Analytical and bioanalytical chemistry》2006,385(7):1298-1303
In the present paper, three approaches are compared for the evaluation of the combined uncertainty in the determination of
mercury in aquatic sediments by an aqua regia extraction procedure. For this, the data obtained in validation studies from
five certified reference materials (CRMs), covering a range of concentrations from 0.8 to 130 mg kg−1 of mercury and analysed by three atomic spectroscopic techniques (cold vapour generation atomic fluorescence spectrometry,
CV-AFS, cold vapour generation atomic absorption spectroscopy, and inductively coupled plasma mass spectroscopy), were considered.
The combined uncertainty was firstly assessed by considering separately the data obtained for each CRM analysed (approach
A). Moreover, this assessment was also performed with two other calculation approaches (B and C) based on the pooled data
obtained from the validation step. The comparison of the results obtained for the different techniques showed a clear bias
effect when using CV-AFS with nitric acid as a diluent. In relation to the strategies tested for the combined uncertainty
assessment, approach C proved to be the easiest and friendliest method for uncertainty assessment.
相似文献
14.
15.
Phillips KM Wolf WR Patterson KY Sharpless KE Holden JM 《Analytical and bioanalytical chemistry》2007,389(1):219-229
Over a 6.5-year period a total of 2554 values were reported by nine laboratories for 259 certified or reference nutrient concentrations
in 26 certified reference materials (CRM) submitted to contract laboratories, blinded, as part of the qualifying process for
analytical contracts and in the routine sample stream as part of the National Food and Nutrient Analysis Program. Each value
was converted to a Z′-score, reflecting the difference from the assigned value related to the combined expected analytical uncertainty plus the
uncertainty in the CRM value. Z′-scores >|3.0| were considered unacceptable. For some nutrients (Na, folate, dietary fiber, pantothenic acid, thiamin, tocopherols,
carotenoids, monounsaturated, and polyunsaturated fatty acids), >20% of Z′-scores were >|3.0|. For total fat, vitamin C, and niacin >25% of Z′-scores were >|2.0|. Components for which CRM data were
best (more than 90% of Z′-scores <|2.0|) were Mg, P, Mn, Se, and vitamin B12. In some cases deviations from assigned values were not uniform across
laboratories and materials. For Na almost all high Z′-scores were for low-Na matrices, suggesting analytical problems related to concentration.
Figure Z′-scores for vitamins in certified reference materials
Disclaimer: Certain commercial equipment, instruments, or materials are identified in this paper in order to specify the experimental
procedure adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute
of Standards and Technology, or the United States Department of Agriculture, nor is it intended to imply that the materials
or equipment identified are necessarily the best available for the purpose. 相似文献
16.
Rosenberg E 《Analytical and bioanalytical chemistry》2008,391(1):33-57
This review discusses the characterisation of natural organic dyestuffs of historical interest by liquid chromatography–mass
spectrometry. The structures of the most important natural organic dyestuffs traditionally used are presented and discussed
from the perspective of their analytical chemical determination. The practical aspects of the determination of this inhomogeneous
range of compounds with different structures, such as anthraquinones, flavonoids, indigoids or tannins, are discussed with
their implications for sample preparation, liquid chromatographic separation and mass spectrometric detection. The particular
focus of this review is the discussion of the mass spectral fragmentation patterns of the different classes of natural organic
dyestuffs, which in the ideal case allow the identification of the dyestuff actually used, and thereby provide a key to the
better characterisation and understanding of historical objects dyed with natural organic dyestuffs.
Figure LC-MS allows characterisation of natural dyestuff constituents: the MS spectrum of alizarin is superimposed over a photo of
a textile coloured using this red dye 相似文献
17.
Margaret C. Kline David L. Duewer John C. Travis Melody V. Smith Janette W. Redman Peter M. Vallone Amy E. Decker John M. Butler 《Analytical and bioanalytical chemistry》2009,394(4):1183-1192
Modern highly multiplexed short tandem repeat (STR) assays used by the forensic human-identity community require tight control
of the initial amount of sample DNA amplified in the polymerase chain reaction (PCR) process. This, in turn, requires the
ability to reproducibly measure the concentration of human DNA, [DNA], in a sample extract. Quantitative PCR (qPCR) techniques
can determine the number of intact stretches of DNA of specified nucleotide sequence in an extremely small sample; however,
these assays must be calibrated with DNA extracts of well-characterized and stable composition. By 2004, studies coordinated
by or reported to the National Institute of Standards and Technology (NIST) indicated that a well-characterized, stable human
DNA quantitation certified reference material (CRM) could help the forensic community reduce within- and among-laboratory
quantitation variability. To ensure that the stability of such a quantitation standard can be monitored and that, if and when
required, equivalent replacement materials can be prepared, a measurement of some stable quantity directly related to [DNA]
is required. Using a long-established conventional relationship linking optical density (properly designated as decadic attenuance)
at 260 nm with [DNA] in aqueous solution, NIST Standard Reference Material (SRM) 2372 Human DNA Quantitation Standard was
issued in October 2007. This SRM consists of three quite different DNA extracts: a single-source male, a multiple-source female,
and a mixture of male and female sources. All three SRM components have very similar optical densities, and thus very similar
conventional [DNA]. The materials perform very similarly in several widely used gender-neutral assays, demonstrating that
the combination of appropriate preparation methods and metrologically sound spectrophotometric measurements enables the preparation
and certification of quantitation [DNA] standards that are both maintainable and of practical utility.
Figure NIST Standard Reference Material (SRM) 2372 Human Quantitation Standard 相似文献
18.
Lobo L Fernandez B Pereiro R Bordel N Sanz-Medel A 《Analytical and bioanalytical chemistry》2007,389(3):743-752
A study about the effect of nitrogen in the calibration curves of a series of analytical emission lines has been carried out
in this work. Fifteen reference materials with different matrices (Fe, Al, Zn, Cu and Ni) were used (three of these reference
materials contain nitrogen in their composition) and plots of intensity versus the product “sputtering rate times element
concentration” were constructed for emission lines of the analytes considered in this work (Al, Fe, Cu, Cr, C, Mo, Zn, Si,
Ti and Ni). Two different fits were performed in each plot, first considering only the points corresponding to samples without
nitrogen in their composition and secondly including all the points. The results show almost negligible differences in the
emission yields calculated. On the other hand, a mixture of Ar containing 0.5% N2 was employed to check if the nitrogen effect was present at higher concentrations than those expected in analysis when samples
with high nitrogen concentrations are used. Differences between the slopes of the calibration curves with the Ar/N2 and pure Ar discharges were obtained (up to 30%). A study of the molecular bands recorded in the spectra when nitrogen is
present in the discharge and determination of the resulting interferences on the analytes have been performed.
Figure Glow discharge powered with radiofrequency energy 相似文献
19.
The use of electrochemical impedance spectroscopy for biosensing 总被引:1,自引:0,他引:1
This review introduces the basic concepts and terms associated with impedance and techniques of measuring impedance. The focus
of this review is on the application of this transduction method for sensing purposes. Examples of its use in combination
with enzymes, antibodies, DNA and with cells will be described. Important fields of application include immune and nucleic
acid analysis. Special attention is devoted to the various electrode design and amplification schemes developed for sensitivity
enhancement. Electrolyte insulator semiconductor (EIS) structures will be treated separately.
Figure An alternating current which is forced to pass an interface is sensitive to surface changes and will detect impedance changes
due to biomolecule immobilisation or formation of a recognition complex. This can be used for the construction of biosensor
electrodes 相似文献
20.
Malachite green oxalate (MG oxalate) and leucomalachite green (LMG) have been prepared and certified as pure reference materials.
The purities of MG oxalate and LMG were assessed by high-performance liquid chromatography–diode array detection (HPLC–DAD),
nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), Karl Fischer titration, ashing and
thermogravimetric analysis (TGA). MG oxalate was purified by supercritical fluid extraction (SFE). Prior to purification,
commercial MG oxalate purity was estimated to be about 90%. The main impurities present in SFE-purified MG oxalate were identified
and quantified using HPLC–DAD. The main impurities were found to be monode-MG (monodemethylated MG oxalate synthesis impurity),
4-(dimethylamino)benzophenone (4-DMABP), MG-carbinol and LMG. The homogeneity of both reference materials was also determined.
Issues associated with the stability of LMG and MG oxalate in solution forced an extensive study investigating different parameters
i.e. solvent, acid, analyte concentration and temperature. MG oxalate (100 μg/mL) was found to be stable in acetonitrile containing
1% v/v glacial acetic acid for at least 155 days and LMG (100 μg/mL) was stable in acetonitrile for at least 133 days. The
final purity value for MG oxalate was 94.3 ± 1.4% m/m at the 95% confidence interval (or 67% m/m if MG cation is reported).
For LMG, the certified purity was found to be 98.8 ± 0.8% m/m at the 95% confidence interval.
Figure Calibration reference materials for malachite green and leucomalachite green, certified for purity, are essential in characterising
these key analytes in a fish matrix reference material 相似文献