共查询到20条相似文献,搜索用时 718 毫秒
1.
I. M. H. Lima M. N. Frota E. A. N. Fernandes P. Bode F. S. Tagliaferro 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(2):389-396
Summary This paper describes an analytical method using a nuclear-related technique for the detection of forbidden doping substances
in the urine of race horses. The proposed method, adapted from the Méthode Alcaline Sur C-18 developed by the French Laboratoire
de Contr?le Antidopage, is based on gas chromatography separation followed by mass spectrometry (GC-MS). The method was validated
for caffeine, identified as the most frequent doping substance in the Brazilian horseracing activity. This validation is also
a major requirement to achieve ISO/IEC 17025 laboratory accreditation. The validation has led to several metrological challenges
because the decisions are largely based on qualitative results (“false-positive” and/or “false-negative”) and the degree of
accuracy, as well as the traceability had to be determined in the absence of certified matrix reference materials. 相似文献
2.
Chromatography: The separation technique of the 20th century 总被引:3,自引:0,他引:3
L. S. Ettre 《Chromatographia》2000,51(1-2):7-17
Summary M. S. Tswett contemplated the possibility of “chromatography” in 1899–1901 while carrying out his first research work on the
physico-chemical structure of plant chlorophylls, and he reported “on a new category of adsorption analysis” in 1903. The
evolution of chromatography followed the advances of this century: each decade brought new innovations based logically from
the previous one. By the end of the 20th Century chromatography has became the most widely used separation technique in chemistry
and biochemistry: thus, it is no exaggeration to call it the separation technique of the 20th Century. This paper investigates
the evolution of the various branches of chromatography.
An essential condition for all fruitful research is to have at one’s disposal a satisfactory technique. “Tout progrès scientific
est un progrès de méthode” as somebody once remarked. Unfortunately the methodology is frequently the weakest aspect of scientific
investigations. 相似文献
3.
Chris Mussell Céline S. J. Wolff Briche Chris Hopley Gavin O’Connor 《Accreditation and quality assurance》2007,12(9):469-474
The method used at LGC for analysis of “total” 19-norandrosterone (19-norandrosterone glucuronide plus “free” 19-norandrosterone)
in urine for the Comité Consultatif pour la Quantité de Matière Pilot Study (CCQM-P68) is described. The analytical method
used was a modified version of the method developed at the National Measurement Institute of Australia, which used a hydrolysis
and derivatisation procedure first described by the German Sports University. This method is routinely used by World Anti-Doping
Agency-accredited laboratories for sports drug testing. The main modifications made to the method were the use of 19-norandrosterone
glucuronide as a calibration standard and 19-norandrosterone glucuronide-d4 as an isotopically labelled internal standard,
and the use of a bench-top quadrupole gas chromatograph–mass spectrometer. The results produced by LGC (2.14 ± 0.15 ng g−1 expanded uncertainty, coverage factor k = 2) were in excellent agreement with those from other participating national metrology institutes and thus further validates
the exact-matching isotope-dilution mass spectrometric procedures used at LGC for a wide range of reference measurement applications,
including measurement of ng g−1 levels of steroids in a biological matrix. 相似文献
4.
Résumé On peut déterminer, grace à l'analyse multi-éléments par activation neutronique et à un réseau de stations multiples, les
concentration et les répartitions de plus de 30 éléments dans un milieu de particules véhiculées dans l'air. Cette étude tente
tout d'abord d'établir la composition du “blanc” local dans une zone industrielle, l'échantillonnage se faisant lorsque les
stations ne sont pas sous l'influence immédiate d'émissions locales. On compare ces niveaux à ceux du “blanc” réel et on soustrait
les contributions naturelles. On choisit les jours d'échantillonnage en fonction des paramètres météorologiques; un essai
de superposition des émissions des industries locales sur ce “blanc” local est alors réalisé. La comparaison des facteurs
d'enrichissement permet l'identification des polluants jouant un r?le significatif dans la zone. On localise les sources principales
en comparant pour différentes stations d'échantillonnage, les concentrations en fonction de la direction du vent.
相似文献
5.
Multivariate analysis of HT/GC-(IT)MS chromatographic profiles of triacylglycerol for classification of olive oil varieties 总被引:1,自引:0,他引:1
Cristina Ruiz-Samblás Luis Cuadros-Rodríguez Antonio González-Casado Francisco de Paula Rodríguez García Paulina de la Mata-Espinosa Juan Manuel Bosque-Sendra 《Analytical and bioanalytical chemistry》2011,399(6):2093-2103
The ability of multivariate analysis methods such as hierarchical cluster analysis, principal component analysis and partial
least squares-discriminant analysis (PLS-DA) to achieve olive oil classification based on the olive fruit varieties from their
triacylglycerols profile, have been investigated. The variations in the raw chromatographic data sets of 56 olive oil samples
were studied by high-temperature gas chromatography with (ion trap) mass spectrometry detection. The olive oil samples were
of four different categories (“extra-virgin olive oil”, “virgin olive oil”, “olive oil” and “olive-pomace” oil), and for the
“extra-virgin” category, six different well-identified olive oil varieties (“hojiblanca”, “manzanilla”, “picual”, “cornicabra”,
“arbequina” and “frantoio”) and some blends of unidentified varieties. Moreover, by pre-processing methods of chemometric
(to linearise the response of the variables) such as peak-shifting, baseline (weighted least squares) and mean centering,
it was possible to improve the model and grouping between different varieties of olive oils. By using the first three principal
components, it was possible to account for 79.50% of the information on the original data. The fitted PLS-DA model succeeded
in classifying the samples. Correct classification rates were assessed by cross-validation. 相似文献
6.
Popot MA Woolfitt AR Garcia P Tabet JC 《Analytical and bioanalytical chemistry》2008,390(7):1843-1852
The insulin-like-growth factor (IGF-I) peptide is considered to be the main indirect marker for growth hormone administration
(GH) in a horse. Further to a previous investigation on measurement of IGF-I in plasma samples by mass spectrometry, this
study focuses on quantitative and qualitative analysis of intact IGF-I in horse plasma. First, protein-transposing software
has been developed for IGF-I to facilitate its quantification by HPLC–electrospray–ion-trap mass spectrometry. Second, product-ion
scan experiments on IGF-I have been conducted on standard samples, non-fortified equine plasma samples, fortified plasma samples,
and equine GH post-administration samples. This “top-down” approach method enables characterisation of fragment ions corresponding
to the carboxy terminal end, which can be useful for the confirmation of the presence of IGF-I in plasma samples.
Figure Structure of IGF-I and amino acid sequences of IGF-I and R3 IGF-I. Deconvolution mass spectra of the IGF-I and R3 IGF-I mixture 相似文献
7.
Theprocessofmembraneinsertionofthetoxicproteincanbedividedintotwosteps:absorptionandinsertion.Theproteinmoleculesfirstinteractwiththemembranesurfaceandbecomeadsorbedontothemembranethroughstaticelectricity.Theconformationofthetoxicproteinwillchangeunde… 相似文献
8.
The potential of a headspace device coupled to multi-capillary column-ion mobility spectrometry has been studied as a screening
system to differentiate virgin olive oils (“lampante,” “virgin,” and “extra virgin” olive oil). The last two types are virgin olive oil samples of very similar characteristics,
which were very difficult to distinguish with the existing analytical method. The procedure involves the direct introduction
of the virgin olive oil sample into a vial, headspace generation, and automatic injection of the volatiles into a gas chromatograph-ion
mobility spectrometer. The data obtained after the analysis by duplicate of 98 samples of three different categories of virgin
olive oils, were preprocessed and submitted to a detailed chemometric treatment to classify the virgin olive oil samples according
to their sensory quality. The same virgin olive oil samples were also analyzed by an expert’s panel to establish their category
and use these data as reference values to check the potential of this new screening system. This comparison confirms the potential
of the results presented here. The model was able to classify 97% of virgin olive oil samples in their corresponding group.
Finally, the chemometric method was validated obtaining a percentage of prediction of 87%. These results provide promising
perspectives for the use of ion mobility spectrometry to differentiate virgin olive oil samples according to their quality
instead of using the classical analytical procedure. 相似文献
9.
Daniel G. Cummings James D. Sommers Mary L. Adamic Marcos Jimenez Jeffrey J. Giglio Kevin P. Carney Karl Grimm 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):923-928
A radioactive 137Cs source has been analyzed for the radioactive parent 137Cs and stable decay daughter 137Ba. The ratio of the daughter to parent atoms is used to estimate the date when Cs was purified prior to source encapsulation
(an “age” since purification). The isotopes were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) after chemical
separation. In addition, Ba was analyzed by isotope dilution ICP-MS (ID-ICP-MS). A detailed error analysis of the mass spectrometric
work has been undertaken to identify areas of improvement, as well as quantifying the effect the errors have on the “age”
determined. This paper reports an uncertainty analysis to identifying areas of improvement and alternative techniques that
may reduce the uncertainties. In particular, work on isotope dilution using ICP-MS for the “age” determination of sealed sources
is presented. The results will be compared to the original work done using external standards to calibrate the ICP-MS instrument. 相似文献
10.
Blagoj S. Mitrevski Prapin Wilairat Philip J. Marriott 《Analytical and bioanalytical chemistry》2010,396(7):2503-2511
This work presents the validation study of the comprehensive two-dimensional gas chromatography (GC×GC)–time-of-flight mass
spectrometry method performance in the analysis of the key World Anti-Doping Agency (WADA) anabolic agents in doping control.
The relative abundance ratio, retention time, identification and other method performance criteria have been tested in the
GC×GC format to confirm that they comply with those set by WADA. Furthermore, tens of other components were identified with
an average similarity of >920 (on the 0–999 scale), including 10 other endogenous sterols, and full mass spectra of 5,000+
compounds were retained. The testosterone/epitestosterone ratio was obtained from the same run. A new dimension in doping
analysis has been implemented by addressing separation improvement. Instead of increasing the method sensitivity, which is
accompanied by making the detector increasingly “blind” to the matrix (as represented by selected ion monitoring mode, high-resolution
mass spectrometry (MS) and tandem MS), the method capabilities have been improved by adding a new “separation” dimension while
retaining full mass spectral scan information. Apart from the requirement for the mass spectral domain that a minimum of three
diagnostic ions with relative abundance of 5% or higher in the MS spectra, all other WADA criteria are satisfied by GC×GC
operation. The minimum of three diagnostic ions arises from the need to add some degree of specificity to the acquired mass
spectrometry data; however, under the proposed full MS scan method, the high MS similarity to the reference compounds offers
more than the required three diagnostic ions for an unambiguous identification. This should be viewed as an extension of the
present criteria to a full-scan MS method. 相似文献
11.
12.
R. A. Nadkarni G. H. Morrison 《Journal of Radioanalytical and Nuclear Chemistry》1977,38(1-2):435-449
A rapid and comprehensive method has been developed for the determination of ppm to sub-ppb amounts of Ru, Pd, Ag, Os, Ir,
Pt and Au, based on thermal neutron irradiation, dissolution of samples, selective absorption on Srafion NMRR ion exchange
resin and high resolution γ-ray spectrometry. Two noble metals “specific” resins were tested for their absorption behaviour.
The method has been used for analysis of standard rocks, ores, minerals, lunar samples, coal, coal fly ash, and several biological
materials. 相似文献
13.
René Dybkaer 《Accreditation and quality assurance》2007,12(10):553-557
Laboratory medicine provides results for quantities as well as for properties having no magnitude. The terminology of the
latter is less well established and sources are contradictory. Two recent papers on “protometrology” published in this journal
offer an opportunity to discuss the necessary concept systems. The delineations of “metrology” versus “protometrology”, “observation”
versus “measurement”, and the generic division of “property” are examined with emphasis on avoiding conflict with the International
Vocabulary of Metrology. It is suggested that having “examination” as a top generic concept coupled with systematic modifiers
for division, especially ‘nominal’ and ‘ordinal’, is a preferable terminological solution.
相似文献
René Dybkaer |
14.
E. A. Schweikert J. R. McGinley G. Francis D. L. Swindle 《Journal of Radioanalytical and Nuclear Chemistry》1974,19(1):89-108
Résumé On décrit l'application de l'analyse par activation aux particules chargées (AAPC) avec mesure après irradiation à la détection
de traces d'oxygène, de bore et de lithium. On utilise l'activation aux protens, aux alpha et aux3He pour le dosage non-destructif de l'oxygene dans le silicium. Les limites de détection expérimentale sont respectivement
de 0,06 ppm, 0,05 ppm et 5 ppb. L'activation aux3He, couplée à une séparation radiochimique après irradiation, a été employée pour les analyses de l'oxygène dans le germanium
avec une limite de détection de 10 ppb. De nouvelles techniques ont été développées pour le dosage du bore et du lithium,
basées sur la mesure du8Li (T: 850 msec) et de12B (T: 20 msec), respectivement et utilisant une technique de mesure β en co?ncidence avec deux scintillateurs minces de plastique.
Les possibilités de cette méthode presque “prompte” sont illustrées avec des résultats concernant le silicium, le germanium
et des échantillons de verre.
相似文献
15.
Matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) imaging of polystyrenes with various molecular masses
was applied to study spatial molecular mass distribution of polymers in sample spots prepared by the “dried droplet” method.
When different solvents and target surfaces were examined, a segregation of single homologous polymers was observed depending
upon the evaporation rate of the solvent. For the observed patterns left by the evaporating droplet, a hypothesis is offered
taking into account different hydrodynamic interactions and diffusion. The results illustrate that spot preparation using
the conventionally “dried droplet” method is prone to artifacts and should be avoided for reliable and reproducible MALDI
mass spectrometry experiments with regards to the determination of molecular masses and mass distributions. 相似文献
16.
Sz. Osváth N. Vajda Zs. Molnár É. Széles Zs. Stefánka 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):675-680
The majority of long-lived radionuclides produced in the nuclear fuel cycle can be regarded as “difficult-to-measure” nuclides,
hence chemical separation is needed before the nuclear measurement of them. A combined radiochemical procedure that enables
the simultaneous determination of some “difficult-to-measure” nuclides in medium and low level radioactive wastes has been
developed in our laboratory. Recently, this method has been extended for determination of 237Np and 93Zr. 237Np and 93Zr are pre-concentrated by co-precipitation on iron(II) hydroxide and zirconium oxide, separated by extraction chromatography
using UTEVA, and measured by inductively coupled plasma mass spectrometry (ICP-MS). As even traces of polyatomic ions and
isotopes at m/z 237 or 93 cause considerable interferences during ICP-MS detection, a purification step by extraction chromatography
was needed. Analyzing real samples (evaporation concentrates of a nuclear power plant) 66–99% and 31–99% chemical yields were
achieved for Np and Zr, respectively. 相似文献
17.
Lei Chen Xianjin Yu Zengdian Zhao 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):187-193
A highly sensitive separation procedure has been developed to investigate uranium and thorium activities and their isotopic
ratios in environmental water samples in Tokushima, Japan. Uranium and thorium isotopes in environmental water samples were
simultaneously isolated from interfering elements with extraction chromatography using an Eichrom UTEVA™ resin column. After
the chemical separation, activities of U and Th isotopes coprecipitated with samarium fluoride (SmF3) were measured by α-spectrometry. It has been confirmed that uranium isotopes are isolated successfully from thorium decay
chains by analyzing a test aqueous solution as a simulation of an environmental water sample. The separation procedure has
been first applicable to the determination of U and Th activities and their isotopic ratios in a drinking well water named
“Kurashimizu” in Tokushima City, Japan. The specific activities of 238U and 232Th in “Kurashimizu” were deduced to be within the upper limits of <0.31 and <0.19 mBq/l, respectively. 相似文献
18.
Summary An analytical evaluation of an HPLC method with diode array detection to separate and quantify polyphenolic compounds from
pears has been made. The method was applied to the quantitative analysis of phenolics from five pear horticultural cultivars
(“Agua”, “Blanquilla”, “Conference”, “Pasagrana” and “Decana”) in both peel and pulp matrices and evaluated for precision
and accuracy. Precision was taken as the reproducibility in peak area of the polyphenols of interest as well as in the slope
of calibration graphs. Values ranged 2–5%. Accuracy was evaluated by recovery of all polyphenolic compounds from both peel
and pulp in all pears investigated. Accuracy values ranged 92–102%, and were independent of the polyphenolic structure, horticultural
cultivar and matrix. Identification was by comparing retention times and UV spectra with those of standards when commercially
available. When not available commercially, provisional identification was according to spectral characteristics as well as
from isolation and hydrolysis data. Application of the method revealed differences between peel and pulp in all cases studied;
the higher levels of phenolics were found in the peels. “Decana” and “Pasagrana” cultivars showed the highest phenolic content
compounds whereas “Conference” showed the lowest. 相似文献
19.
P. Tighe 《Accreditation and quality assurance》2000,5(12):488-490
The need for “quality” in near patient testing (NPT) has been acknowledged since the mid 1980s. The commonest biochemical
NPT device is the dry reagent strip or “dipstick” for urinalysis. Dipsticks may be read in three ways, against the color chart
printed along the side of the bottle, using a benchreader (the color chart printed on a flat card) or using an electronic
reader. This report uses the results of a urinalysis quality assurance (QA) program, over 1998, to evaluate the “error” rates
which occur using the three different reading methods. The QA samples are buffered aqueous solutions which are “spiked” to
give concentrations midway between two color blocks for each analyte. Results are scored as ±1 if a color block adjacent to
the target value, ±2 for results two color blocks (defined as “error”) and ±3 for results three color blocks (defined as “gross
error”) from the target value. Analysis of the results show that the error rates are similar reading visually by either method,
but greatly reduced when read electronically. Some persisting errors when using the electronic reader are explained by observation
studies. The study highlights the value of a urinalysis QA program for NPT urinalysis in understanding the error rates of
this simple but ubiquitous test.
Received: 10 July 2000 / Accepted: 10 July 2000 相似文献
20.
I. V. Ukrainets N. L. Bereznyakova V. A. Parshikov O. I. Naboka 《Chemistry of Heterocyclic Compounds》2008,44(2):178-183
A large series of 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acid anilides has been prepared as potential diuretic agents.
The effect of all of the synthesized compounds on the urinary function of the kidney has been investigated. The appearance
of a “structure — diuretic activity” relationship is discussed.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 239–245, February, 2008. 相似文献