共查询到20条相似文献,搜索用时 218 毫秒
1.
Pérez Pavón JL García Pinto C Guerrero Peña A Moreno Cordero B 《Analytical and bioanalytical chemistry》2008,391(2):599-607
In the present work we report the results obtained with a methodology based on direct coupling of a headspace generator to
a mass spectrometer for the identification of different types of petroleum crudes in polluted soils. With no prior treatment,
the samples are subjected to the headspace generation process and the volatiles generated are introduced directly into the
mass spectrometer, thereby obtaining a fingerprint of volatiles in the sample analysed. The mass spectrum corresponding to
the mass/charge ratios (m/z) contains the information related to the composition of the headspace and is used as the analytical signal for the characterization
of the samples. The signals obtained for the different samples were treated by chemometric techniques to obtain the desired
information. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation
are required. The method is rapid, simple and, in view of the results, highly promising for the implementation of a new approach
for oil spill identification in soils.
Figure PCA score plots illustrate clear discrimination of types of crude oil in polluted soil samples (e.g. results are shown for
vertisol) 相似文献
2.
Patricia W. Stege Lorena L. Sombra Germán A. Messina Luis D. Martinez María F. Silva 《Analytical and bioanalytical chemistry》2009,394(2):567-573
Many aromatic compounds can be found in the environment as a result of anthropogenic activities and some of them are highly
toxic. The need to determine low concentrations of pollutants requires analytical methods with high sensitivity, selectivity,
and resolution for application to soil, sediment, water, and other environmental samples. Complex sample preparation involving
analyte isolation and enrichment is generally necessary before the final analysis. The present paper outlines a novel, simple,
low-cost, and environmentally friendly method for the simultaneous determination of p-nitrophenol (PNP), p-aminophenol (PAP), and hydroquinone (HQ) by micellar electrokinetic capillary chromatography after preconcentration by cloud
point extraction. Enrichment factors of 180 to 200 were achieved. The limits of detection of the analytes for the preconcentration
of 50-ml sample volume were 0.10 μg L−1 for PNP, 0.20 μg L−1 for PAP, and 0.16 μg L−1 for HQ. The optimized procedure was applied to the determination of phenolic pollutants in natural waters from San Luis,
Argentina.
Figure Schematic representation of the cloud point extraction process. 相似文献
3.
Maher F. El-Zohry Thanaa A. Mohamed Essam M. Hussein 《Monatshefte für Chemie / Chemical Monthly》2009,140(3):265-272
Abstract 2-Methylbenzimidazole 1 reacted with 3-dicyanomethylidine-1-ethyl-2-oxoindoline 2 in ethyl acetate to afford 1-amino-2-cyano-3,4-dihydro-1′-ethylspiro{benzimidazo[1,2-a]pyridine-3,3′-indolin}-2′-one 6, which was used as a key intermediate in the synthesis of fused spiropolyheterocyclic derivatives of benzimidazopyridopyrimidine
and/or benzimidazonaphthyridine nucleus incorporating an indoline moiety.
Graphical abstract
相似文献
4.
Determining sulfamonomethoxine and its acetyl/hydroxyl metabolites in chicken plasma under organic solvent-free conditions 总被引:1,自引:0,他引:1
Furusawa N 《Analytical and bioanalytical chemistry》2006,385(8):1570-1574
A quantitative technique is described for a sample preparation followed by high performance liquid chromatography method for
the simultaneous determination of sulfamonomethoxine and its metabolites, N
4-acetyl SMM and 2,6-dihydroxy SMM, in chicken plasma. The average recoveries, analytical total time, and limits of quantitation
were ≥80% (relative standard deviations (SD) ≤6%), <30 min sample-1 (12 samples in 2 h), and ≤0.09 μg ml−1, respectively. The procedure, performed under 100% aqueous conditions, uses no organic solvents and toxic reagents at all
and is, therefore, harmless to the environment and humans.
相似文献
5.
A novel on-column sequential preconcentration method based on the combination of field-amplified sample injection induced
by acetonitrile and pseudo isotachophoresis (ITP)–acid stacking is developed for simply but efficiently concentrating alkaloid
cations in a high-salt sample matrix in capillary electrophoresis. Acetonitrile (70%) added to a sample solution with a high-salt
sample matrix not only induces field-amplified sample stacking by decreasing conductivity but also acts as a termination reagent
in the succeeding pseudo ITP. After sample injection had been completed, a plug of H+ was injected electrokinetically and a neutralization reaction between H+ and tartrate from the buffer solution produced a low conductivity zone, in which the injected analyte cations were further
concentrated. With the sequential preconcentration method, a 3 orders of magnitude detection sensitivity (1,400-fold) increase
could be observed compared with the conventional electrokinetic injection method, without compromising separation efficiency
and peak shape, and detection limits of 0.1 ng/mL for myosmine and 0.3 ng/mL for anabasine with the conditions selected were
achieved. The calibration curves demonstrated good linearity in the concentration ranges 1.3–600 ng/mL for myosmine and 4.9–900 ng/mL
for anabasine, respectively. The proposed method has been used to analyze successfully trace alkaloids in cigarette samples.
Figure Sequential preconcentration processes: a sample injection; b introduction of HCl; c capillary zone electrophoresis separation. A
−
tartrate, white circles acetonitrile, black circles Na+, sample zone, myosmine, anabasine 相似文献
6.
Stratis-Cullum DN Griffin GD Mobley J Vo-Dinh T 《Analytical and bioanalytical chemistry》2008,391(5):1655-1660
This paper reports the first intensified biochip system for chemiluminescence detection and the feasibility of using this
system for the analysis of biological warfare agents is demonstrated. An enzyme-linked immunosorbent assay targeting Bacillus globigii spores, a surrogate species for Bacillus anthracis, using a chemiluminescent alkaline phosphatase substrate is combined with a compact intensified biochip detection system.
The enzymatic amplification was found to be an attractive method for detection of low spore concentrations when combined with
the intensified biochip device. This system was capable of detecting approximately 1 × 105
Bacillus globigii spores. Moreover, the chemiluminescence method, combined with the self-contained biochip design, allows for a simple, compact
system that does not require laser excitation and is readily adaptable to field use.
Figure Schematic diagram of the miniature biochip detection system 相似文献
7.
The sensitivity of Lepidium sativum L. germination to three imidazolium ionic liquids was investigated in solutions and soils artificially contaminated with
mixtures of those compounds. In case of aquatic solutions, the toxic character of analyzed compounds is connected with their
hydrophobicity. The seedling growth is increasing with the decrease in ionic liquid hydrophobicity. The novelty of those studies
is the application of high-performance liquid chromatography, which was used for the determination of ionic liquid quantity
absorbed by cress. There was almost linear relationship between decrease in root germination and amount of ionic liquid uptaken
by cress. Furthermore, the systematic studies on the influence of total organic carbon content in soil on the toxicity of
ionic liquids to cress were performed for the first time. Hazardous effects appeared to be closely connected with organic
matter: with the decrease of total organic carbon quantity, the inhibition of plant growth was more significant. Visual effects
of ionic liquid toxic activity to garden cress are similar as in the case of nutrient deficit in plants.
Figure Visual phytotoxicity effects observed during the test; leaf chromatosis: light green and yellow (up photos), violet (lower
photos) 相似文献
8.
We have developed an iterative procedure for predicting the retention times of polycyclic aromatic hydrocarbons (PAHs) and
n-alkanes during separations by temperature-programmed gas chromatography. The procedure is based on estimates of two thermodynamic
properties for each analyte (the differences in enthalpy and entropy associated with movements between the stationary and
mobile phases) derived from data acquired experimentally in separations under isothermal conditions at temperatures spanning
the range covered by the temperature programs in ten-degree increments. The columns used for this purpose were capillary columns
containing polydimethylsiloxane-based stationary phases with three degrees of phenyl substitution (0%, 5%, and 50%). Predicted
values were mostly within 1% of experimentally determined values, implying that the method is stable and precise.
Figure Predicted values were mostly within 1 % of experimentally determined values, thus implying that the method is stable and precise 相似文献
9.
Manas Chakrabarty Sulakshana Karmakar Ratna Mukherjee Shiho Arima Yoshihiro Harigaya 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):375-380
Abstract 1-Alkyl/phenyl-2-arylbenzimidazoles have been synthesized in very good to excellent yields by a one-pot condensation of N-alkyl/phenyl-o-phenylenediamines with aryl aldehydes in water at room temperature using cetylpyridinium bromide as a cheap and eco-friendly
catalyst.
Graphical abstract
相似文献
10.
Sugar alcohols are widely used as food additives and drug excipients. Erythritol (INS 968) is an important four-carbon sugar
alcohol in the food industry. Erythritol occurs naturally in certain fruits, vegetables, and fermented foods. Currently, HPLC
and GC methods are in use for the quantification of erythritol in natural/processed foods. However, an immunoassay for erythritol
has not been developed so far. We have utilized affinity-purified erythritol-specific antibodies generated earlier [9] to develop an indirect competitive ELISA. With erythritol–BSA conjugate (54 mol/mol; 100 ng/well) as the coating antigen,
a calibration curve was prepared using known amounts of standard meso-erythritol (0.1–100,000 ng) in the immunoassay. Watermelon (Citrullus lanatus) and red wine were selected as the food sources containing meso-erythritol. The amount of meso-erythritol was calculated as 2.36 mg/100 g fresh weight of watermelon and 206.7 mg/L of red wine. The results obtained from
the immunoassay are in close agreement with the reported values analyzed by HPLC and GC (22–24 mg/kg in watermelon and 130–300 mg/L
in red wine). The recovery analyses showed that added amounts of meso-erythritol were recovered fairly accurately with recoveries of 86–105% (watermelon) and 85–93.3% (red wine). The method described
here for erythritol is the first report of an immunoassay for a sugar alcohol.
Figure Indirect competitive ELISA for quantitation of erythritol 相似文献
11.
Abstract One-pot, three-components synthesis of 2,4,6-triarylpyridines and 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones was performed under solvent-free conditions using molecular iodine as the catalyst in moderate to good product yields.
Graphical abstract
相似文献
12.
Ortega-Algar S Ramos-Martos N Molina-Díaz A 《Analytical and bioanalytical chemistry》2008,391(2):715-719
A single optosensing device based on lanthanide-sensitized luminescence was developed for determination of p-aminobenzoic acid (PABA). The method is based on the formation of a complex between PABA and Tb(III) immobilized on the solid
phase (QAE A-25 resin) placed inside the flow cell. NaCl (1 M) was used as carrier solution and HCl (0.05 M) as eluent. The
sample solutions of PABA (100 μL) containing Tb(III) and buffered at pH = 6.0 were injected into the carrier stream and the
luminescence was measured at λ
ex = 290 nm and λ
em = 546 nm. The method shows a linear range from 0.2 to 6.0 μg mL−1 with an RSD of 1.2% (n = 10) and a sampling frequency of 22 h−1. A remarkable characteristic of the method is its high selectivity which allows it to be satisfactorily applied to the analysis
of PABA in pharmaceutical samples without prior treatment.
Figure Typical emission bands of Tb(III) in a solid-phase PABA–Tb(III) luminescence spectrum 相似文献
13.
The metabolism of the selective estrogen receptor modulator toremifene was simulated in an on-line electrochemistry/enzyme
reactor/liquid chromatography/mass spectrometry system. To simulate the oxidative phase I metabolism, toremifene was oxidized
in an electrochemical (EC) flow-through cell at 1,500 mV vs. Pd/H2 to its phase I metabolites, some of which are reactive quinoid species. In the presence of glutathione-S-transferase (GST), these quinoid compounds react with glutathione, which is also the common detoxification mechanism in the
body. While reacting with glutathione, the chlorine atom is eliminated from the toremifene moiety. Due to higher conversion
rates, GST supplied in continuous flow proved to be more efficient than using immobilized GST on magnetic microparticles.
In the absence of GST, not all GSH adducts are formed, proving the necessity of a phase II enzyme to simulate the complete
metabolic pathway of xenobiotics in an on-line EC/LC/MS system.
Figure Mass voltammogram of toremifene 相似文献
14.
Wael A. El-Sayed Ibrahim F. Nassar Adel A.-H. Abdel-Rahman 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):365-370
Abstract New C-furyl glycosides bearing pyrazolines, isoxazolines, and dihydropyrimidine-2(1H)-thiones were synthesized in order to increase the number of tested compounds screened for antimicrobial activity. The antimicrobial
activity screening showed that the pyrazoline derivatives were the most active compounds.
Graphical abstract
相似文献
15.
Khemiri A Galland A Vaudry D Chan Tchi Song P Vaudry H Jouenne T Cosette P 《Analytical and bioanalytical chemistry》2008,390(7):1861-1871
Bacterial surface-associated proteins play crucial roles in host–pathogen interactions and pathogenesis. The identification
of these proteins represents an important goal of bacterial proteomics for vaccine development, but also for environmental
concerns such as microbial biosensing. Here, we developed such an approach for Legionella pneumophila, a bacterium that causes severe pneumonia. We propose a complementary strategy consisting of (1) a fluorescent labelling
of surface-exposed proteins in parallel with (2) a fractionation of the outer-membrane protein extract. These two distinct
protein populations were subsequently separated using two-dimensional gel electrophoresis and characterised by mass spectrometry.
Within these populations, we found proteins which were expected for the compartments studied, but also a great number of proteins
never experimentally described, and also a non-negligible fraction of proteins never described in these fractions. These data
provided new routes of inspection for transport and host recognition for Legionella pneumophila. In addition, these results on the membranome and surfaceome show that Legionella in the stationary phase of growth possesses the major determinants to infect host cells.
Figure Electron micrograph of Legionella pneumophila in stationnary phase of growth
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Presented at the Annual French National Symposium on Mass Spectrometry, Electrophoresis and Proteomics, 20–23 September 2007
in Pau, France 相似文献
16.
Zaher M Ravelet C Baussanne I Ravel A Grosset C Décout JL Peyrin E 《Analytical and bioanalytical chemistry》2009,393(2):655-660
In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new
dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl
anchor system efficiently (1.15 μmol/m2) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting
coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.
Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase 相似文献
17.
18.
Infrared absorption (IR) and vibrational and electronic circular dichroism (VCD and ECD, respectively) spectra of tert-butylcarbamoylquinine (t-BuCQN) and pseudoenantiomeric tert-butylcarbamoylquinidine (t-BuCQD), denoted as selectors (SO), complexed with chiral (S) and (R)-3,5-dinitrobenzoylleucine (DNB-Leu) and achiral 3,5-dinitrobenzoylglycine (DNB-Gly), denoted as selectands (SA), in methanol
and acetonitrile, with the spectra of pure SA and SO are reported. H–D exchange of exchangeable hydrogen atoms of SA and SO
in deuterated methanol which occurs in IR and VCD experiments is exploited to identify Amide II and Amide III vibrational
modes. The formation of preferentially bound complexes composed of sterically compatible combinations of DNB-Leu and SO are
manifested by increased intensity of VCD bands assigned to vibrations of amide, carbamate, quinoline, and dissociated carboxylate
group and also by increased ECD signals. The VCD technique revealed similarities between the strongly bound diastereomeric
complex of chiral DNB-Leu and SO and the complex of achiral DNB-Gly and SO, highlighting the leading role of SO in the formation
of SA–SO complex.
Figure Vibrational circular dichroism study: Interaction markers typical of the binding between the quinine selector and the derivatized
amino acid selectand 相似文献
19.
Nagnnath D. Kokare Devanand B. Shinde 《Monatshefte für Chemie / Chemical Monthly》2009,140(2):185-188
Abstract Aromatic aldoximes were converted to the corresponding nitriles in good to excellent yields by employing phosphoric acid diethyl
ester 2-phenylbenzimidazol-1-yl ester as reagent. The method was equally effective for oximes bearing electron-donating and
electron-withdrawing substituents.
Graphical Abstract
相似文献