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1.
Joan O. Grimalt Mike Howsam Daniel Carrizo Raquel Otero Mary Rosa Rodrigues de Marchi Esther Vizcaino 《Analytical and bioanalytical chemistry》2010,396(6):2265-2272
A rapid, robust and economical method for the analysis of persistent halogenated organic compounds in small volumes of human
serum and umbilical cord blood is described. The pollutants studied cover a broad range of molecules of contemporary epidemiological
and legislative concern, including polychlorobiphenyls (PCBs), polychlorobenzenes (CBs), hexachlorocyclohexanes (HCHs), DDTs,
polychlorostyrenes (PCSs) and polybromodiphenyl ethers (PBDEs). Extraction and clean-up with n-hexane and concentrated sulphuric acid was followed with analysis by gas chromatography coupled to electron capture (GC-ECD)
and GC coupled to negative ion chemical ionisation mass spectrometry (GC-NICI-MS). The advantages of this method rest in the
broad range of analytes and its simplicity and robustness, while the use of concentrated sulphuric acid extraction/clean-up
destroys viruses that may be present in the samples. Small volumes of reference serum between 50 and 1000 μL were extracted
and the limits of detection/quantification and repeatability were determined. Recoveries of spiked compounds for the extraction
of small volumes (≥300 μL) of the spiked reference serum were between 90% and 120%. The coefficients of variation of repeatability
ranged from 0.1–14%, depending on the compound. Samples of 4-year-old serum and umbilical cord blood (n = 73 and 40, respectively) from a population inhabiting a village near a chloro-alkali plant were screened for the above-mentioned
halogenated pollutants using this method and the results are briefly described. 相似文献
2.
Ahn KC Gee SJ Kim HJ Aronov PA Vega H Krieger RI Hammock BD 《Analytical and bioanalytical chemistry》2011,401(4):1285-1293
Pyrethroid insecticides widely used in forestry, agricultural, industrial, and residential applications have potential for
human exposure. Short sample preparation time and sensitive, economical high-throughput assays are needed for biomonitoring
studies that analyze a large number of samples. An enzyme-linked immunosorbent assay (ELISA) was used for determining 3-phenoxybenzoic
acid (3-PBA), a general urinary biomarker of exposure to some pyrethroid insecticides. A mixed-mode solid-phase extraction
reduced interferences from acid hydrolyzed urine and gave 110 ± 6% recoveries from spiked samples. The method limit of quantification
was 2 μg/L. Urine samples were collected from forestry workers that harvest pine cone seeds where pyrethroid insecticides
were applied at ten different orchards. At least four samples for each worker were collected in a 1-week period. The 3-PBA
in workers classified as high, low, or no exposure based on job analysis over all sampling days was 6.40 ± 9.60 (n = 200), 5.27 ± 5.39 (n = 52), and 3.56 ± 2.64 ng/mL (n = 34), respectively. Pair-wise comparison of the differences in least squares means of 3-PBA concentrations among groups
only showed a significant difference between high and no exposure. Although this difference was not significant when 3-PBA
excretion was normalized by creatinine excretion, the general trend was still apparent. No significant differences were observed
among days or orchards. This ELISA method using a 96-well plate was performed as a high-throughput tool for analyzing around
300 urine samples measured in triplicate to provide data for workers exposure assessment. 相似文献
3.
Patel II Trevisan J Singh PB Nicholson CM Krishnan RK Matanhelia SS Martin FL 《Analytical and bioanalytical chemistry》2011,401(3):969-982
Vibrational spectroscopy techniques can be applied to identify a susceptibility-to-adenocarcinoma biochemical signature. A
sevenfold difference in incidence of prostate adenocarcinoma (CaP) remains apparent amongst populations of low- (e.g. India)
compared with high-risk (e.g. UK) regions, with migrant studies implicating environmental and/or lifestyle/dietary causative
factors. This study set out to determine the biospectroscopy-derived spectral differences between risk-associated cohorts
to CaP. Benign prostate tissues were obtained using transurethral resection from high-risk (n = 11, UK) and low-risk (n = 14, India) cohorts. Samples were analysed using attenuated total reflection Fourier-transform infrared (FTIR) spectroscopy,
FTIR microspectroscopy and Raman microspectroscopy. Spectra were subsequently processed within the biochemical cell region
(1,800−1–500 cm–1) employing principal component analysis (PCA) and linear discriminant analysis (LDA) to determine whether wavenumber–absorbance/intensity
relationships might reveal biochemical differences associated with region-specific susceptibility to CaP. PCA-LDA scores and
corresponding cluster vector plots identified pivotal segregating biomarkers as 1,582 cm−1 (Amide I/II trough); 1,551 cm−1 (Amide II); 1,667 cm−1 (Amide I); 1,080 cm−1 (DNA/RNA); 1,541 cm−1 (Amide II); 1,468 cm−1 (protein); 1,232 cm−1 (DNA); 1,003 cm−1 (phenylalanine); 1,632 cm−1 [right-hand side (RHS) Amide I] for glandular epithelium (P < 0.0001) and 1,663 cm−1 (Amide I); 1,624 cm−1 (RHS Amide I); 1,126 cm−1 (RNA); 1,761, 1,782, 1,497 cm−1 (RHS Amide II); 1,003 cm−1 (phenylalanine); and 1,624 cm−1 (RHS Amide I) for adjacent stroma (P < 0.0001). Primarily protein secondary structure variations were biomolecular markers responsible for cohort segregation
with DNA alterations exclusively located in the glandular epithelial layers. These biochemical differences may lend vital
insights into the aetiology of CaP. 相似文献
4.
Sommers CD Ye H Kolinski RE Nasr M Buhse LF Al-Hakim A Keire DA 《Analytical and bioanalytical chemistry》2011,401(8):2445-2454
We evaluated polyacrylamide gel electrophoresis (PAGE) and size exclusion chromatography coupled with multi-angle laser light
scattering (SEC-MALLS) approaches to determine weight-average molecular weight (M
w) and polydispersity (PD) of heparins. A set of unfractionated heparin sodium (UFH) and low-molecular-weight heparin (LMWH) samples obtained from
nine manufacturers which supply the US market were assessed. For SEC-MALLS, we measured values for water content, refractive
index increment (dn/dc), and the second virial coefficient (A
2) for each sample prior to molecular weight assessment. For UFH, a mean ± standard deviation value for M
w of 16,773 ± 797 was observed with a range of 15,620 to 18,363 (n = 20, run in triplicate). For LMWHs by SEC-MALLS, we measured mean M
w values for dalteparin, tinzaparin, and enoxaparin of 6,717 ± 71 (n = 4), 6,670 ± 417 (n = 3), and 3,959 ± 145 (n = 3), respectively. PAGE analysis of the same UFH, dalteparin, tinzaparin, and enoxaparin samples showed values of 16,135 ± 643
(n = 20), 5,845 ± 45 (n = 4), 6,049 ± 95 (n = 3), and 4,772 ± 69 (n = 3), respectively. These orthogonal measurements are the first M
w results obtained with a large heparin sample set on product being marketed after the heparin crisis of 2008 changed the level
of scrutiny of this drug class. In this study, we compare our new data set to samples analyzed over 10 years earlier. In addition,
we found that the PAGE analysis of heparinase digested UFH and neat LMWH samples yield characteristic patterns that provide
a facile approach for identification and assessment of drug quality and uniformity. 相似文献
5.
We report the results of abundant plasma protein depletion on the analysis of underivatized N-linked glycans derived from plasma proteins by nanoLC Fourier-transform ion cyclotron resonance mass spectrometry. N-linked glycan profiles were compared between plasma samples where the six most abundant plasma proteins were depleted (n = 3) through a solid-phase immunoaffinity column and undepleted plasma samples (n = 3). Three exogenous glycan standards were spiked into all samples which allowed for normalization of the N-glycan abundances.
The abundances of 20 glycans varying in type, structure, composition, and molecular weight (1,200–3,700 Da) were compared
between the two sets of samples. Small fucosylated non-sialylated complex glycans were found to decrease in abundance in the
depleted samples (greater than or equal to tenfold) relative to the undepleted samples. Protein depletion was found to marginally
effect (less than threefold) the abundance of high mannose, hybrid, and large highly sialylated complex species. The significance
of these findings in terms of future biomarker discovery experiments via global glycan profiling is discussed. 相似文献
6.
Neopterin is a valuable biomarker of cellular immunity associated with various pathological situations such as viral and bacterial
infections, autoimmune, cardiovascular, neurodegenerative and malignant disorders. To produce specific antibodies against
neopterin for a rapid multi-biomarker-based diagnosis, a novel hapten derivative was synthesized and attached to carrier proteins.
The thoroughly characterized conjugates were used for immunization of BALB/c mice and rabbits. The produced monoclonal antibody
reached in both direct and indirect enzyme-linked immunosorbent assay (ELISA) format LoD of 0.18 and 0.45 μg L−1, respectively, and was a superior immunoreagent for further biosensor developments with regard to assay sensitivity and material
availability. The best polyclonal antibody was somewhat more sensitive in direct ELISA with LoD of 0.05 μg L−1. The optimized ELISA method was evaluated with blood samples collected from patients with renal insufficiency, patients with
sepsis, patients without confirmed clinical diagnosis, and healthy volunteers. In plasma samples, neopterin concentrations
ranging from 3.2 to 103 μg L−1 could be determined with the monoclonal ELISA whereas twofold lower results were obtained with the polyclonal ELISA. A satisfactory
correlation of results was found between the polyclonal ELISA and IBL Neopterin ELISA kit within the concentration range 0.5–16 μg L−1 (R = 0.874; n = 40), and slightly lower correlation was found for monoclonal-based ELISA (R = 0.819; n = 40). These data show that the generated antibodies may be used as functional analytical reagents for the integration into
multianalyte biochip detection systems. 相似文献
7.
1H NMR-based metabolomics approach for exploring urinary metabolome modifications after acute and chronic physical exercise 总被引:1,自引:0,他引:1
C. Enea F. Seguin J. Petitpas-Mulliez N. Boildieu N. Boisseau N. Delpech V. Diaz M. Eugène B. Dugué 《Analytical and bioanalytical chemistry》2010,396(3):1167-1176
Metabolomics is a comprehensive method for metabolite assessment that involves measuring the overall metabolic signature of
biological samples. We used this approach to investigate biochemical changes due to acute and chronic physical exercise. Twenty-two
women using identical oral contraceptives were segregated into an untrained (n = 10) or trained (n = 12) group depending on their physical training background. The subjects performed two exercises in a randomized order:
a prolonged exercise test (75% of their
\mathop V· \textO2 max \mathop V\limits^\cdot {{\text{O}}_{2\,\;\max }} until exhaustion) and a short-term, intensive exercise test (short-term, intensive exercise anaerobic test). Urine specimens
were collected before and 30 min after each test. The samples were analyzed by 1H NMR spectroscopy, and multivariate statistical techniques were utilized to process the data. Distinguishing characteristics
were observed only in the urine profiles of specimens collected before vs. 30 min after the short-term, intensive exercise
test. The metabolites responsible for such changes were creatinine, lactate, pyruvate, alanine, β-hydroxybutyrate, acetate,
and hypoxanthine. In both groups, the excretion of lactate, pyruvate, alanine, β-hydroxybutyrate, and hypoxanthine increased
similarly after the completion of the short-term, intensive exercise test (p < 0.03). However, acetate excretion increased to a lesser extent in trained than in untrained subjects (p < 0.05). In conclusion, metabolomics is a promising tool in order to gain insight into physiological status and to clarify
the changes induced by short-term, intense physical exercise. 相似文献
8.
C. Ramírez M. J. Abad J. Cano J. López P. Nogueira L. Barral 《Colloid and polymer science》2001,279(2):184-189
Enthalpy relaxation in a system containing the diglycidyl ether of bisphenol A (DGEBA) resin and a diamine, 1,3-bisaminomethylcyclohexane
(1,3-BAC) as curing agent, has been investigated by differential scanning calorimetry (DSC). Samples fully cured were annealed
at temperature Tg–15 °C for periods of time from 1 h to a maximum of 168 h. The enthalpy relaxation is analyzed by the peak shift method, in
which the sample is heated at 10 °C/min following cooling at various rates through the glass transition region. The key parameters
of structural relaxation determined were the non-linearity parameter x=0.47 ± 0.02, the apparent activation energy Δh*=1264 ± 48 kJ/mol or Δh*/R=152 ± 6 kK and the non-exponentiality parameter β ≈ 0.3. The results, obtained by the same method, were compared with those for other systems based on fully cured DGEBA. The
correlations among these parameters with the peak shift model should be considered with caution. However, the results show
that a correlation between crosslink lengths and the value of Δh* can be considered. The relaxation process for DGEBA/1,3-BAC proves to be highly cooperative.
Received: 28 June 2000 Accepted: 6 September 2000 相似文献
9.
Roberto Iglesias Rodríguez Manuel Fernández Delgado Julia Barciela García Rosa María Peña Crecente Sagrario García Martín Carlos Herrero Latorre 《Analytical and bioanalytical chemistry》2010,397(6):2603-2614
This paper has a double objective. The first goal was to develop an authentication system to differentiate between traditional
orujo alcoholic distillates with and without a certified brand of origin (CBO). Owing to their low price and quality, samples without
a CBO can be used as substrates for falsification of genuine CBO ones. The second objective was to perform a comparison of
the abilities of the different chemometric procedures employed for this classification. The classification was performed on
the basis of the chemical information contained in the metal composition of the orujo distillates. Eight metals determined by electrothermal atomic absorption spectrometry and inductively coupled plasma optical
emission spectrometry were considered (Ca, Cd, Cr, Cu, K, Mg, Na and Ni). After the appropriate pretreatment, the data were
processed using different chemometric techniques. In the first stage, principal component analysis and cluster analysis were
employed to reveal the latent structure contained in the data. Once it had been demonstrated that a relation exists between
the metal composition and the raw materials, and not between the metal composition and the distillation systems employed for
the orujo production, the second step consisted in the comparative application of different supervised pattern recognition procedures
(such as linear discriminant analysis, K-nearest neighbours, soft independent modelling of class analogy, UNEQ and different artificial neural network approaches,
including multilayer feed-forward, support vector machines, learning vector quantization and probabilistic neural networks).
The results showed the different capabilities of the diverse classification techniques to discriminate between Galician orujo samples. The best results were those provided by probabilistic neural networks, in which the correct recognition abilities
for CBO classes and without CBO classes were 98.6 ± 3.1 and 98.0 ± 4.5%; the prediction results were 87.7 ± 3.3 and 86.2 ± 5.0%,
respectively. The usefulness of chemical metal analysis in combination with chemometric techniques to develop a classification
procedure to authenticate Galician CBO orujo samples is demonstrated. 相似文献
10.
Evaluation of a novel ELISA for serotonin: urinary serotonin as a potential biomarker for depression
Nichkova MI Huisman H Wynveen PM Marc DT Olson KL Kellermann GH 《Analytical and bioanalytical chemistry》2012,402(4):1593-1600
Depression is a common disorder with physical and psychological manifestations often associated with low serotonin. Since
noninvasive diagnostic tools for depression are sparse, we evaluated the clinical utility of a novel ELISA for the measurement
of serotonin in urine from depressed subjects and from subjects under antidepressant therapy. We developed a competitive ELISA
for direct measurement of serotonin in derivatized urine samples. Assay performance was evaluated and applied to clinical
samples. The analytical range of the assay was from 6.7 to 425 μg serotonin/g creatinine (Cr). The limit of quantification
was 4.7 μg/g Cr. The average recovery for spiked urine samples was 104.4%. Average intra-assay variation was 4.4%, and inter-assay
variation was <20%. The serotonin analysis was very specific. No significant interferences were observed for 44 structurally
and nonstructurally related urinary substances. Very good correlation was observed between urinary serotonin levels measured
by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS; ELISA = 1.16 × LC-MS/MS − 53.8; r = 0.965; mean % bias = 11%; n = 18). Serotonin was stable in acidified urine for 30 days at room temperature and at −20 °C. The established reference range
for serotonin was 54–366 μg/g Cr (n = 64). Serotonin levels detected in depressed patients (87.53 ± 4.89 μg/g Cr; n = 60) were significantly lower (p < 0.001) than in nondepressed subjects (153.38 ± 7.99 μg/g Cr). Urinary excretion of serotonin in depressed individuals significantly
increased after antidepressant treatment by 5-hydroxy-tryptophane and/or selective serotonin re-uptake inhibitor (p < 0.01). The present ELISA provides a convenient and robust method for monitoring urinary serotonin. It is suitable to monitor
serotonin imbalances and may be particularly helpful in evaluating antidepressant therapies. 相似文献
11.
Metabolites of synthetic pyrethroids such as cis-3-(2,2-dibromovinyl)-2,2-di-methylcyclo-propane-1-carboxylic acid, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid), 3-phenoxybenzoic acid (3-PBA), and 4-fluoro-3-PBA are
biomarkers for exposure to phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin, and permethrin. In this study,
the pyrethroid metabolites in workers’ urine samples were monitored for the first time with a novel sample pretreatment process
combining hollow fiber liquid phase microextraction (HF-LPME) and in-syringe derivatization (ISD) followed by gas chromatography–electron
capture detector (GC-ECD) analysis. A micro-syringe pre-filled with derivatizing agents and syringe needle connected to an
extracting solvent impregnated hollow fiber segment was used as the LPME probe. Pyrethroid metabolites were extracted and
enriched simultaneously from urine samples by HF-LPME sampling and acid hydrolysis at 70 °C for 10 min. After sampling, the
ISD was performed by mixing the extracting solution and derivatizing agents through plunger movements, followed by GC-ECD
analysis. Parameters influencing the HF-LPME efficiency and ISD were investigated and optimized. Under optimum conditions,
the method provided enrichment factors of 69.8–154.6, repeatability from 5.0 to 12% (n = 5), and good linearity (R
2 = 0.9980–0.9998) for interested analytes spiked in urine samples. The method detection limits ranged from 1.6 to 17 ng/mL.
A comparison was performed between the proposed method and conventional methods. The proposed method was applied to analyze
pyrethroid metabolites in the urine samples collected from workers of pesticide formulation plants. The results suggested
that the proposed HF-LPME coupled ISD method was a rapid, simple, efficient, and eco-friendly technique in the biomonitoring
of metabolites of pyrethroids in workers’ urine. 相似文献
12.
Kokot ZJ Matysiak J Urbaniak B Dereziński P 《Analytical and bioanalytical chemistry》2011,399(7):2487-2494
The aim of this study was to develop a new precise and accurate CZE-DAD method for honeybee venom analysis using cytochrome
c as an internal standard. The 64.5 cm total length, 56 cm effective length, 75 μm ID, and 360 μm OD uncoated fused-silica
capillary was used. The samples were injected into the capillary under a 50-mbar pressure for 7 s. There were 15 kV of electric
field across the capillary applied. The current intensity was 26 μA. The separation was carried out at 25 °C. The analysis
was run with the normal electrode polarity. The following steps and parameters were taken into account for the validation
of the developed method: selectivity, precision, accuracy, linearity, limit of detection and limit of quantitation. All steps
of the validation procedure proved that the developed analytical procedure was suitable for its intended purpose. Possibly
this was the first study in which several honeybee venom components were separated and five of them were identified by capillary
zone electrophoresis. In addition, the developed method was applied for quantitative analysis of 38 honeybee venom samples.
The content (relative to the dry venom mass) of analyzed peptides in honeybee venom samples collected in 2002–2007 was as
follows: apamine from 0.93% to 4.34% (mean, 2.85 ± 0.79%); mast cell degranulating peptide (MCDP) from 1.46% to 4.37% (mean,
2.82 ± 0.64%); phospholipase A2 from 7.41% to 20.25% (mean, 12.95 ± 3.09%); melittin from 25.40% to 60.27%, (mean, 45.91 ± 9.78%). The results were compared
with the experimental data obtained for the same venom samples analyzed earlier by the HPLC method. It was stated that HPCE
and HPLC data did not differ significantly and that the HPCE method was the alternative for the HPLC method. Moreover, using
the results obtained principal component analysis (PCA) was applied to clarify the general distribution patterns or similarities
of four major honeybee venom constituents collected from two different bee strains in various months and years. PCA has shown
that the strain of bee appears to be the only criteria for bee venom sample classification. Strong correlations between apamine,
MCDP, phospholipase A2, and melittin were confirmed. These correlations have to be taken into account in the honeybee venom standardization. The
developed method due to its simplicity can be easily automated and incorporated into routine operations both in the bee venom
identification, quality control, and standardization of the product. 相似文献
13.
Al-Dirbashi OY Al-Hassnan ZN Rashed MS 《Analytical and bioanalytical chemistry》2006,386(7-8):2013-2017
A liquid chromatography tandem mass spectrometric method is described for the analysis of homocitrulline in human urine, a
key metabolite in the differential diagnosis of hyperammonemia, hyperornithinemia, homocitrullinuria (HHH) syndrome. Urine
samples were prepared by mere five-fold dilution with a mixture of internal standards (2H2-citrulline and 2H3-creatinine) used for the simultaneous quantification of creatinine. Analytes were separated on a cyano column and eluted
isocratically within seven min. Detection was achieved by monitoring transitions of 190 > 84 and 190 > 127 for homocitrulline,
178 > 115 for 2H2-citrulline, 114 > 44 for creatinine and 117 > 47 for 2H3-creatinine. Calibration curves were linear up to 100 micromol/L. Intraday (n = 7) and interday (n = 6) variations were less than 10%. In urine samples from three siblings confirmed to have HHH syndrome, homocitrulline levels
were at 13.3 (74), 21.1 (50) and 108.2 (103) mmol/mol creatinine (micromol/L). Control values were 0–9 mmol/mol creatinine
(n = 120). The current method solves specificity issues in homocitrulline determination often encountered with some ninhydrin-based
systems (coelution with methionine) and some o-phthalaldehyde-based ones (coelution with taurine), and presents an attractive alternative with a relatively high throughput. 相似文献
14.
M. Vallejo A. García J. Tuñón D. García-Martínez S. Angulo J.L. Martin-Ventura L. M. Blanco-Colio P. Almeida J. Egido C. Barbas 《Analytical and bioanalytical chemistry》2009,394(6):1517-1524
New biomarkers of cardiovascular disease are needed to augment the information obtained from traditional indicators and to
illuminate disease mechanisms. One of the approaches used in metabolomics/metabonomics for that purpose is metabolic fingerprinting
aiming to profile large numbers of chemically diverse metabolites in an essentially nonselective way. In this study, gas chromatography-mass
spectrometry was employed to evaluate the major metabolic changes in low molecular weight plasma metabolites of patients with
acute coronary syndrome (n = 9) and with stable atherosclerosis (n = 10) vs healthy subjects without significant differences in age and sex (n = 10). Reproducible differences between cases and controls were obtained with pattern recognition techniques, and metabolites
accounting for higher weight in the classification have been identified through their mass spectra. On this basis, it seems
inherently plausible that even a simple metabolite profile might be able to offer improved clinical diagnosis and prognosis,
but in addition, specific markers are being identified. 相似文献
15.
C. Gómez J. Segura N. Monfort T. Suominen A. Leinonen M. Vahermo J. Yli-Kauhaluoma R. Ventura 《Analytical and bioanalytical chemistry》2010,397(7):2903-2916
The objective of the present study was to investigate mesocarb metabolism in humans. Samples obtained after administration
of mesocarb to healthy volunteers were studied. The samples were extracted at alkaline pH using ethyl acetate and salting-out
effect to recover metabolites excreted free and conjugated with sulfate. A complementary procedure was applied to recover
conjugates with glucuronic acid or with sulfate consisting of the extraction of the urines with XAD-2 columns previously conditioned
with methanol and deionized water; the columns were then washed with water and finally eluted with methanol. In both cases,
the dried extracts were reconstituted and analyzed by ultra-performance liquid chromatography–tandem mass spectrometry. Chromatographic
separation was carried out using a C18 column (100 mm × 2.1 mm i.d., 1.7 μm particle size) and a mobile phase consisting of water and acetonitrile with 0.01% formic
acid with gradient elution. The chromatographic system was coupled to a mass spectrometer with an electrospray ionization
source working in positive mode. Metabolic experiments were performed in multiple-reaction monitoring mode by monitoring one
transition for each potential mesocarb metabolite. Mesocarb and 19 metabolites were identified in human urine, including mono-,
di-, and trihydroxylated metabolites excreted free as well as conjugated with sulfate or glucuronic acid. All metabolites
were detected up to 48 h after administration. The structures of most metabolites were proposed based on data from reference
standards available and molecular mass and product ion mass spectra of the peaks detected. The direct detection of mesocarb
metabolites conjugated with sulfate and glucuronic acid without previous hydrolysis has been described for the first time.
Finally, a screening method to detect the administration of mesocarb in routine antidoping control analyses was proposed and
validated based on the detection of the main mesocarb metabolites in human urine (p-hydroxymesocarb and p-hydroxymesocarb sulfate). After analysis of several blank urines, the method demonstrated to be specific. Extraction recoveries
of 100.3 ± 0.8 and 105.9 ± 10.8 (n = 4), and limits of detection of 0.5 and 0.1 ng mL−1 were obtained for p-hydroxymesocarb sulfate and p-hydroxymesocarb, respectively. The intra- and inter-assay precisions were estimated at two concentration levels, 50 and 250 ng
mL−1, and relative standard deviations were lower than 15% in all cases (n = 4). 相似文献
16.
Analysis of the stable isotope ratio of carbon (δ
13C) and α-linolenic acid (C18:3ω3) content in milk fat is a useful indicator of organic milk production. Referring to corresponding
measurements, further analyses of stable isotope ratios were performed in 120 samples of conventionally and organically produced
whole milk collected from German retailers during a period of 18 months. Conventional milk predominantly exhibited higher
δ
15N values than organic milk, the latter of which never exceeded a maximum δ
15N threshold value of 5.50‰. Measurements of δ
34S did not differ significantly between organic and conventional milk. Because δ
13C, in general, is related to maize consumption, δ
13C in milk protein and δ
13C in milk fat were equally suited for authentication of organic milk. Thus, a high correlation (r = 0.99) was established between δ
13C in milk protein and lipids. Although occurring on different levels in organic and conventional milk, the relatively constant
fractionation of carbon isotopes between protein and fat will allow for the advanced detection of adulteration in processed
milk products, such as fraudulent combinations of organic milk fat and conventional skim milk. In addition to the strong correlation
between C18:3ω3 and δ
13Cprotein (r = −0.91), a mutual dependence was identified between both δ
13Cprotein and δ
15N (r = 0.66) and C18:3ω3 and δ
15N (r = −0.61). Thus, multi-variable analyses are useful to increase robustness and reduce the number of exceptions in organic
milk authentication. Future work involving multivariate statistical analysis can possibly further improve milk authentication
in various respects including differentiating between brands of retail milk. 相似文献
17.
Franziska Nehring Dorrit E. Jacob Matthias G. Barth Stephen F. Foley 《Mikrochimica acta》2008,160(1-2):153-163
Trace element determination in rocks by fusion on an iridium strip heater followed by LA-ICP-MS analysis of the glass beads
is extended here to SiO2-rich rocks; rapid fusion of samples with >55 wt% SiO2 is facilitated by dilution by high purity MgO. The method developed here can rapidly and accurately determine numerous trace
elements in a large range of rock compositions in a short time (about 50 samples/day). Systematic evaluation for a large range
of rock compositions (natural rocks and reference materials AGV-2, GSP-2, JG-1a) with SiO2 contents between 45 and 80 wt% shows that reproducibility and accuracy within 10% can be routinely achieved for most of the
28 trace elements investigated (Rb, Sr, Cs, Ba, Ti, Zr, Hf, Nb, Ta, Sc, V, Cr, Ni, Pb, Th, U, REE). The 40 mg sample size
is smaller than for XRF, INAA or solution-ICP-MS, detection limits are lower, and trace element palettes more complete than
XRF and INAA. This microchemical method is thus attractive for the analysis of all natural geological materials as well as
for experimental applications with small samples. Samples with SiO2-contents >55 wt% require hot and long melting to achieve homogeneous glasses and eliminate all residual minerals, particularly
refractory accessory phases. Melting conditions of 1600 °C and 20 s for samples are recommended for SiO2 contents between 55 and 70 wt%, whereas 1800 °C and 20–30 s are often required for samples with >70 wt% SiO2. Problems are encountered for Pb and Cs due to volatilization on the Ir strip, for Sc due to interferences, and Zr and Hf
due to their sequestration in refractory accessory minerals.
Correspondence: Franziska Nehring, Department of Geosciences, University of Mainz, Becherweg 21, 55099 Mainz, Germany 相似文献
18.
Johanna Ristimaa Merja Gergov Anna Pelander Erja Halmesmäki Ilkka Ojanperä 《Analytical and bioanalytical chemistry》2010,398(2):925-935
Analysis of the major drugs of abuse in meconium has been established in clinical practice for detecting fetal exposure to
illicit drugs, particularly for the ready availability of the sample and ease of collection from diapers, compared with neonatal
hair and urine. Very little is known about the occurrence and detection possibilities of therapeutic and licit drugs in meconium.
Meconium specimens (n = 209) were collected in delivery hospitals, from infants of mothers who were suspected to be drug abusers. A targeted analysis
method by liquid chromatography–triple quadrupole mass spectrometry (LC-MS/MS) was developed for abused drugs: amphetamine,
methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, morphine, codeine, 6-monoacetylmorphine,
oxycodone, methadone, tramadol, buprenorphine, and norbuprenorphine. A separate LC-MS/MS method was developed for 11-nor-∆9-tetrahydrocannabinol-9-carboxylic acid. A screening method based on LC coupled to time-of-flight MS was applied to a broad
spectrum of drugs. As a result, a total of 77 different compounds were found. The main drug findings in meconium were as follows:
local anesthetics 82.5% (n = 172), nicotine or its metabolites 61.5% (n = 129), opioids 48.5% (n = 101), stimulants 21.0% (n = 44), hypnotics and sedatives 19.0% (n = 40), antidepressants 18.0% (n = 38), antipsychotics 5.5% (n = 11), and cannabis 3.0% (n = 5). By revealing drugs and metabolites beyond the ordinary scope, the present procedure helps the pediatrician in cases
where maternal denial is strong but the infant seems to suffer from typical drug-withdrawal symptoms. Intrapartum drug administration
cannot be differentiated from gestational drug use by meconium analysis, which affects the interpretation of oxycodone, tramadol,
fentanyl, pethidine, and ephedrine findings. 相似文献
19.
T. Hellweg C. D. Dewhurst E. Brückner K. Kratz W. Eimer 《Colloid and polymer science》2000,278(10):972-978
Poly (N-isopropylacrylamide) microgel particles are found to form colloidal crystals similar to those occurring in typical hard-sphere
colloids like poly(methylmethacrylate) beads. Samples made of particles with different cross-linker concentrations are investigated
and their deswelling ratio is determined using dynamic light scattering. Small-angle neutron scattering data are also presented
and analysed in terms of a face-centred-cubic crystal structure. The characteristic length, a, of the elementary cell is found to be 535 ± 16 and 495 ± 15 nm for the two systems investigated. This leads to particle
radii of 189 ± 6 and 175 ± 5 nm, respectively. These values compare well to the radii determined using several different methods.
Received: 26 July 1999/Accepted: 21 March 2000 相似文献
20.
Kishore Kumar Pasikanti Juwita Norasmara Shirong Cai Ratha Mahendran Kesavan Esuvaranathan Paul C. Ho Eric Chun Yong Chan 《Analytical and bioanalytical chemistry》2010,398(3):1285-1293
In this study, gas chromatography mass spectrometry (GC-MS) and two-dimensional gas chromatography time-of-flight mass spectrometry
(GC×GC-TOFMS) were employed for the metabolic footprinting of a pair of immortalized human uroepithelial cells namely HUC-1
(nontumorigenic) and HUC T-2 (tumorigenic). Both HUC-1 and HUC T-2 cell lines were cultivated in 1 mL of Ham’s F-12 media.
Subsequent to 48 h of incubation, 200 μL of cell culture supernatant was protein-precipitated using 1.7 mL of methanol and
an aliquot of 1.5 mL of the mixture was separated, dried, trimethylsilyl-derivatized, and analyzed using GC-MS and GC×GC-TOFMS.
Metabolic profiles were analyzed using multivariate data analysis techniques to evaluate the changes of the metabolomes. Both
GC-MS and GC×GC-TOFMS analyses showed distinct differences in metabolic phenotypes of the normal and tumorigenic human bladder
cells (partial least squares-discriminant analysis (PLS-DA) of GC×GC-TOFMS data; two latent variables, R
2
X = 0.418, R
2
Y = 0.977 and Q
2 (cumulative) = 0.852). Twenty metabolites were identified as being statistically different between the two cell types. These
metabolites revealed that several key metabolic pathways were perturbed in tumorigenic urothelial cells as compared to the
normal cells. Application of GC×GC-TOFMS offered several advantages compared to classical one-dimensional GC-MS which include
enhanced chromatographic resolution (without increase in analytical run time), increase in sensitivity, improved identification
of metabolites, and also separation of reagent artifacts from the metabolite peaks. Our results reinforced the advantages
of GC×GC-TOFMS and the role of metabolomics in characterizing bladder cancer biology using in vitro cell culture models. 相似文献