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1.
A survey of contamination of surface and drinking waters around Lake Maggiore in Northern Italy with polar anthropogenic environmental
pollutants has been conducted. The target analytes were polar herbicides, pharmaceuticals (including antibiotics), steroid
estrogens, perfluorooctanesulfonate (PFOS), perfluoroalkyl carboxylates (including perfluorooctanoate PFOA), nonylphenol and
its carboxylates and ethoxylates (NPEO surfactants), and triclosan, a bactericide used in personal-care products. Analysis
of water samples was performed by solid-phase extraction (SPE) then liquid chromatography–triple-quadrupole (tandem) mass
spectrometry (LC–MS–MS). By extraction of 1-L water samples and concentration of the extract to 100 μL, method detection limits
(MDLs) as low as 0.05–0.1 ng L−1 were achieved for most compounds. Lake-water samples from seven different locations in the Southern part of Lake Maggiore
and eleven samples from different tributary rivers and creeks were investigated. Rain water was also analyzed to investigate
atmospheric input of the contaminants. Compounds regularly detected at very low concentrations in the lake water included:
caffeine (max. concentration 124 ng L−1), the herbicides terbutylazine (7 ng L−1), atrazine (5 ng L−1), simazine (16 ng L−1), diuron (11 ng L−1), and atrazine-desethyl (11 ng L−1), the pharmaceuticals carbamazepine (9 ng L−1), sulfamethoxazole (10 ng L−1), gemfibrozil (1.7 ng L−1), and benzafibrate (1.2 ng L−1), the surfactant metabolite nonylphenol (15 ng L−1), its carboxylates (NPE1C 120 ng L−1, NPE2C 7 ng L−1, NPE3C 15 ng L−1) and ethoxylates (NPE
n
Os, n = 3-17; 300 ng L−1), perfluorinated surfactants (PFOS 9 ng L−1, PFOA 3 ng L−1), and estrone (0.4 ng L−1). Levels of these compounds in drinking water produced from Lake Maggiore were almost identical with those found in the lake
itself, revealing the poor performance of sand filtration and chlorination applied by the local waterworks. 相似文献
2.
MSPD procedure for determining buprofezin,tetradifon, vinclozolin,and bifenthrin residues in propolis by gas chromatography–mass spectrometry 总被引:1,自引:0,他引:1
dos Santos TF Aquino A Dórea HS Navickiene S 《Analytical and bioanalytical chemistry》2008,390(5):1425-1430
A simple and effective extraction method based on matrix solid-phase dispersion (MSPD) was developed to determine bifenthrin,
buprofezin, tetradifon, and vinclozolin in propolis using gas chromatography–mass spectrometry in selected ion monitoring
mode (GC–MS, SIM). Different method conditions were evaluated, for example type of solid phase (C18, alumina, silica, and Florisil), the amount of solid phase and eluent (n-hexane, dichloromethane, dichloromethane–n-hexane (8:2 and 1:1, v/v) and dichloromethane–ethyl acetate (9:1, 8:2 and 7:3, v/v)). The best results were obtained using 0.5 g propolis, 1.0 g silica as dispersant sorbent, 1.0 g Florisil as clean-up sorbent,
and dichloromethane–ethyl acetate (9:1, v/v) as eluting solvent. The method was validated by analysis of propolis samples fortified at different concentration levels
(0.25 to 1.0 mg kg−1). Average recoveries (four replicates) ranged from 67% to 175% with relative standard deviation between 5.6% and 12.1%. Detection
and quantification limits ranged from 0.05 to 0.10 mg kg−1 and 0.15 to 0.25 mg kg−1 propolis, respectively. 相似文献
3.
R. Rahnama Kozani Y. Assadi F. Shemirani M. R. Milani Hosseini M. R. Jamali 《Chromatographia》2007,66(1-2):81-86
Dispersive liquid–liquid microextraction (DLLME) has been used for preconcentration of trihalomethanes (THMs) in drinking
water. In DLLME an appropriate mixture of an extraction solvent (20.0 μL carbon disulfide) and a disperser solvent (0.50 mL
acetone) was used to form a cloudy solution from a 5.00-mL aqueous sample containing the analytes. After phase separation
by centrifugation the enriched analytes in the settled phase (6.5 ± 0.3 μL) were determined by gas chromatography with electron-capture
detection (GC–ECD). Different experimental conditions, for example type and volume of extraction solvent, type and volume
of disperser solvent, extraction time, and use of salt, were investigated. After optimization of the conditions the enrichment
factor ranged from 116 to 355 and the limit of detection from 0.005 to 0.040 μg L−1. The linear range was 0.01–50 μg L−1 (more than three orders of magnitude). Relative standard deviations (RSDs) for 2.00 μg L−1 THMs in water, with internal standard, were in the range 1.3–5.9% (n = 5); without internal standard they were in the range 3.7–8.6% (n = 5). The method was successfully used for extraction and determination of THMs in drinking water. The results showed that
total concentrations of THMs in drinking water from two areas of Tehran, Iran, were approximately 10.9 and 14.1 μg L−1. Relative recoveries from samples of drinking water spiked at levels of 2.00 and 5.00 μg L−1 were 95.0–107.8 and 92.2–100.9%, respectively. Comparison of this method with other methods indicates DLLME is a very simple
and rapid (less than 2 min) method which requires a small volume of sample (5 mL). 相似文献
4.
Directly suspended droplet liquid–liquid–liquid microextraction (LLLME) has been used to determine residues of diclofenac
(2-[2-(2,6-dichlorophenyl) aminophenyl] ethanoic acid), in environmental water samples. In this technique a free suspended
droplet of an aqueous solvent is delivered to the top-center position of an immiscible organic solvent floating on the top
of an aqueous sample while being agitated by a stirring bar placed on the bottom of the sample cell. Recently, diclofenac
was found as an environmental contaminant in sewage, surface, ground and drinking water samples. In the present work, diclofenac
was extracted from water samples by LLLME and analysed by HPLC with UV detection at 281 nm. Factors such as organic solvent,
extraction and back extraction times, stirring rate and the pH of acceptor and donor phases were optimized. Enrichment factor
and detection limit (LOD, n = 7) were 102 and 0.1 μg L−1, respectively. The linearity ranged from 0.5 to 2,000 μg−1 with a %RSD (n = 5) of 7.2 at S/N = 3. All experiments were carried out at room temperature (22 ± 0.5 °C). 相似文献
5.
The amount of volatile dimethylselenide (DMSe) in breath has been monitored after ingestion of sub-toxic amounts of selenium
(300 μg 77Se, as selenite) by a healthy male volunteer. The breath samples were collected in Tedlar bags every hour in the first 12 h
and then at longer intervals for the next 10 days. The samples were subjected to speciation analysis for volatile selenium
compounds by use of cryotrapping–cryofocussing–GC–ICP–MS. Simultaneously, all urine was collected and subjected to total selenium
determination by use of ICP–MS. By monitoring m/z 82 and 77, background or dietary selenium and selenium from the administered selenite were simultaneously determined in the
urine and in the breath—dietary selenium only was measured by monitoring m/z 82 whereas the amount of spiked 77Se (99.1% [enriched spike]) and naturally occurring selenium (7.6% [natural abundance]) were measured by monitoring m/z 77. Quantification of DMSe was performed by using DMSe gas samples prepared in Tedlar bags (linear range 10–300 pg, R
2=0.996, detection limit of Se as DMSe was 10 pg Se, or 0.02 ng L−1, when 0.5 L gas was collected). Dimethylselenide was the only selenium species detected in breath samples before and after
the ingestion of 77Se-enriched selenite. Additional DM77Se was identified as early as 15 min after ingestion of the isotopically-labelled selenite. Although the maximum concentration
of 77Se in DMSe was recorded 90 min after ingestion, the natural isotope ratio for selenium in DMSe (77/82) was not reached after
20 days. The concentration of DMSe correlated with the total Se concentration in the urine during the experiment (R
2=0.80). Furthermore, the sub-toxic dose of 300 μg selenium led to a significant increase of DMSe and renal excretion of background
selenium, confirming that selenium ingested as selenite is homeostatically controlled by excretion. The maximum concentration
of DMSe resulting from the spiked selenite was 1.4 ng Se L−1 whereas the dietary background level was less than 0.4 ng Se L−1. Overall excretion as DMSe was calculated to be 11.2% from the ingested selenite within the first 10 days whereas urinary
excretion accounts for nearly 18.5%. 相似文献
6.
Although there is increasing concern about residues from personal care products entering the aquatic environment and their
potential to accumulate to levels that pose a health threat to humans and wildlife, we still know little about the extent
and magnitude of their presence in the aquatic environment. In this study we describe a procedure for isolation, and subsequent
determination, of compounds commonly added to personal care products. The compounds of interest include UV filters with the
commercial name Eusolex (homosalate, 4-methylbenzylidenecamphor, benzophenone-3, octocrylene, butylmethoxydibenzoylmethane,
ethylhexyl methoxycinnamate) and two common anti-microbial agents, clorophene and triclosan. Water samples were filtered,
acidified, and extracted by use of solid-phase extraction. Extracted compounds were then derivatised before analysis by gas
chromatography–mass spectroscopy. By use of our method we obtained limits of detection of 13–266 ng L−1 for UV filters, and 10–186 ng L−1 for triclosan and clorophene. Recoveries were 82–98% for deionised water and 50–98% for natural water (seawater, pool water,
lake water, and river water). Samples collected in Slovenia included seventeen recreational waters (seawater, pool water,
lake water, and river water; August 2004) and four wastewaters (January 2005). The most abundant UV filter was benzophenone-3
(11–400 ng L−1). Of the two anti-microbial agents studied, trace amounts, only, of triclosan were present in the river Kolpa (68 ng L−1) and in an hospital effluent (122 ng L−1). 相似文献
7.
Zang X Wang J Wang O Wang M Ma J Xi G Wang Z 《Analytical and bioanalytical chemistry》2008,392(4):749-754
A novel method was developed for the determination of captan, folpet, and captafol in apples by dispersive liquid–liquid microextraction
(DLLME) coupled with gas chromatography–electron capture detection (GC–ECD). Some experimental parameters that influence the
extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, and
addition of salt, were studied and optimized to obtain the best extraction results. Under the optimum conditions, high enrichment
factors for the compounds were achieved ranging from 824 to 912. The recoveries of fungicides in apples at spiking levels
of 20.0 μg kg−1 and 70.0 μg kg−1 were 93.0–109.5% and 95.4–107.7%, respectively. The relative standard deviations (RSDs) for the apple samples at 30.0 μg kg−1 of each fungicide were in the range from 3.8 to 4.9%. The limits of detection were between 3.0 and 8.0 μg kg−1. The linearity of the method ranged from 10 to 100 μg kg−1 for the three fungicides, with correlation coefficients (r
2) varying from 0.9982 to 0.9997. The obtained results show that the DLLME combined with GC–ECD can satisfy the requirements
for the determination of fungicides in apple samples.
Figure Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–electron capture detection (GC–ECD) allows
satisfactory determination of fungicides in apple samples 相似文献
8.
Arsenic-speciation analysis in marine samples was performed by high-pressure liquid chromatography (HPLC) with ICP–MS detection.
Separation of eight arsenic species—AsIII, MMA, DMA, AsV, AB, TMAO, AC and TeMAs+—was achieved on a C18 column with isocratic elution (pH 3.0), under which conditions AsIII and MMA co-eluted. The entire separation was accomplished in 15 min. The HPLC–ICP–MS detection limits for the eight arsenic
species were in the range 0.03–0.23 μg L−1 based on 3σ for the blank response (n=5). The precision was calculated to be 2.4–8.0% (RSD) for the eight species. The method was successfully applied to several
marine samples, e.g. oysters, fish, shrimps, and marine algae. Low-power microwave digestion was employed for extraction of
arsenic from seafood products; ultrasonic extraction was employed for the extraction of arsenic from seaweeds. Separation
of arsenosugars was achieved on an anion-exchange column. Concentrations of arsenosugars 2, 3, and 4 in marine algae were
in the range 0.18–9.59 μg g−1.
This paper was presented at the European Winter Conference 2005 相似文献
9.
A multi-component method focussing on thorough sample preparation has been developed for simultaneous analysis of swine manure
for three classes of antibiotic—tetracyclines, sulfonamides, and tylosin. Liquid manure was initially freeze-dried and homogenised
by pulverization before extraction by pressurised liquid extraction. The extraction was performed at 75°C and 2,500 psig in
three steps using two cycles with 0.2 mol L−1 citric acid buffer (pH 4.7) and one cycle with a mixture of 80% methanol with 0.2 mol L−1 citric acid (pH 3). After liquid–liquid extraction with heptane to remove lipids, the pH of the manure was adjusted to 3
with formic acid and the sample was vacuum-filtered through 0.6 μm glass-fibre filters. Finally the samples were pre-concentrated
by tandem SPE (SAX-HLB). Recoveries were determined for manure samples spiked at three concentrations (50–5,000 μg kg−1 dry matter); quantification was achieved by matrix-matched calibration. Recoveries were >70% except for oxytetracycline (42–54%),
sulfadiazine (59–73%), and tylosin (9–35%) and did not vary with concentration or from day-to-day. Limits of quantification
(LOQ) for all compounds, determined as a signal-to-noise ratio of 10, were in the range 10–100 μg kg−1 dry matter. The suitability of the method was assessed by analysis of swine manure samples from six different pig-production
sites, e.g. finishing pigs, sows, or mixed production. Residues of antibiotics were detected in all samples. The largest amounts
were found for tetracyclines (up to 30 mg kg−1 dry matter for the sum of CTC and ECTC). Sulfonamides were detected at concentrations up to 2 mg kg−1 dry matter (SDZ); tylosin was not detected in any samples.
相似文献
10.
Self-consistent reaction field calculation of solvent reorganization energy in electron transfer: a dipole-reaction field interaction model 总被引:1,自引:0,他引:1
Based on the continuum dielectric model, this work has established the relationship between the solvent reorganization energy
of electron transfer (ET) and the equilibrium solvation free energy. The dipole-reaction field interaction model has been
proposed to describe the electrostatic solute-solvent interaction. The self-consistent reaction field (SCRF) approach has
been applied to the calculation of the solvent reorganization energy in self-exchange reactions. A series of redox couples,
O2/O−
2, NO/NO+, O3/O−
3, N3/N−
3, NO2/NO+
2, CO2/CO−
2, SO2/SO−
2, and ClO2/ClO−
2, as well as (CH2)2C-(-CH2-)
n
-C(CH2)2 (n=1 ∼ 3) model systems have been investigated using ab initio calculation. For these ET systems, solvent reorganization energies
have been estimated. Comparisons between our single-sphere approximation and the Marcus two-sphere model have also been made.
For the inner reorganization energies of inorganic redox couples, errors are found not larger than 15% when comparing our
SCRF results with those obtained from the experimental estimation. While for the (CH2)2C–(–CH2–)
n
–C(CH2)2 (n=1 ∼ 3) systems, the results reveal that the solvent reorganization energy strongly depends on the bridge length due to the
variation of the dipole moment of the ionic solute, and that solvent reorganization energies for different systems lead to
slightly different two-sphere radii.
Received: 19 April 2000 / Accepted: 6 July 2000 / Published online: 27 September 2000 相似文献
11.
Fentanyl is a very potent synthetic narcotic analgesic. Because of its strong sedative properties, it has become an analogue
of illicit drugs such as heroin. Its unambiguous detection and identification in environmental samples can be regarded as
strong evidence of its illicit preparation. In this paper we report application of single-drop microextraction (SDME) for
analysis of water samples spiked with fentanyl. Experimental conditions which affect the performance of SDME, for example
the nature of the extracting solvent, sample stirring speed, extraction time, ionic strength, and solution pH, were optimized.
The method was found to be linear in the concentration range 0.10–10 ng mL−1. The limits of quantitation and detection of the method were 100 pg mL−1 and <75 pg mL−1, respectively. This technique is superior to other sample-preparation techniques because of the simple experimental set-up,
short analysis time, high sensitivity, and minimum use of organic solvent. 相似文献
12.
Amereih S Meisel T Kahr E Wegscheider W 《Analytical and bioanalytical chemistry》2005,383(7-8):1052-1059
Speciation analysis of Sb(III) and Sb(V) in a soil sample was performed through extraction and on-line isotope dilution concentration
determination after a chromatographic separation. The total Sb concentration found in a through traffic contaminated soil
sample was (4.17 μg g−1, 0.3 μg g−1 SD, n=6). It was determined using ICP-MS after soil digestion using the sodium peroxide sintering method. The optimized extraction
procedure for speciation analysis was carried out using 100 mmol L−1 citric acid at pH 2.08 by applying an ultrasonic bath for 45 min at room temperature. The effects of citric acid concentration
(0–500 mmol L−1), pH (1–6), and temperature (30–60°C) on inorganic antimony species distribution in the examined sample were studied and
optimized. The separation of Sb(III) and Sb(V) was achieved using an anion exchange column (PRP-X100) and 10 mmol L−1 EDTA and 1 mmol L−1 phthalic acid at pH 4.5 as a mobile phase. The eluent from the HPLC was mixed with an enriched (94.2%) 123Sb spike solution that was pumped by a peristaltic pump with a constant flow rate (0.5 mL min−1) in a three-way valve. The blend passed directly to the Conikal nebulizer of the ICP-MS. By using the above extraction procedure
and methodology, 43.2% Sb(V) (2.9% RSD, n=3) and 6.0% Sb(III) (1.3% RSD, n=3) of total Sb found in the sample could be detected. The detection limits achieved by the proposed method were 20 ng L−1 and 65 ng L−1 for Sb(V) and Sb(III), respectively. The precision, evaluated by using RSD with 100 ng L−1 calibration solutions, was 2.7% and 3.2% (n=6) for Sb(V) and Sb(III), respectively, in aqueous solutions. 相似文献
13.
The present work describes a headspace single-drop microextraction (HS-SDME) method in conjunction with gas chromatography
electron capture detection (GC–ECD) for the determination of an organophosphate insecticide, chlorpyrifos-ethyl (CPF), in
rat liver. Sample preparation included tissue homogenization with methanol in the presence of anhydrous sodium sulfate in
order to isolate CPF from the matrix, followed by dilution with 10 mL of 0.1 M H2SO4 and headspace microextraction to a 2-μL drop of 1-octanol. The main factors affecting extraction efficiency were optimized
[temperature 90 °C, preheating and extraction times of eight and six minutes, respectively, 2 g of (NH4)2SO4, stirring rate of 1000 rpm, 200 μL of methanolic extract]. The method allows for the separation and quantitation of residue
levels of CPF in the livers of rats exposed orally to that insecticide. Using internal standardization (with chlorpyrifos-methyl
used as an internal standard), the linearity of the method was demonstrated in the range 10–2500 ng g−1 with a correlation coefficient R > 0.996 and a satisfactory level of precision (RSD 3.85%, n = 6). Moreover, the results obtained with the new method do not differ from those obtained with the conventional residue
method used in our laboratory. The feasibility of this HS-SDME approach as an equivalent analytical method for the determination
of CPF in rat liver that possessess advantages such as low cost, low solvent consumption and high throughput was confirmed.
Figure Headspace single-drop microextraction 相似文献
14.
A rapid and simple procedure for the determination of antioxidants and preservatives in cosmetics has been developed utilizing
solid-phase microextraction combined with GC–MS. A silica fiber coated with polyacrylate provided the highest extraction efficiency.
Detection limits in the range from 0.4 to 8.5 ng mL−1 were obtained. Linearity is over a wide range from 1 to 2,000 ng mL−1 with a relative standard deviation under 16%. Cosmetic from a local supermarket were analysed for antioxidants and preservatives
to demonstrate the effectiveness of the proposed method. The concentration of antioxidants and preservatives determined was
20–1,218 μg g−1 for methylparaben and 5–3,779 μg g−1 for propylparaben. 相似文献
15.
Bravo M Lespes G De Gregori I Pinochet H Gautier MP 《Analytical and bioanalytical chemistry》2005,383(7-8):1082-1089
A method based on Headspace solid-phase microextraction (HS-SPME, with a 100 μm PDMS-fiber) in combination with gas-chromatography
and pulsed flame-photometric detection (GC-PFPD) has been investigated for simultaneous determination of eight organotin compounds.
Monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPhT), and the semi-volatile diphenyltin (DPhT), triphenyltin
(TPhT), monooctyltin (MOcT), and dioctyltin (DOcT) were determined after derivatization with sodium tetraethylborate. The
conditions used for the extraction and preconcentration step were optimised by experimental design methodology. Tripropyltin
(TPrT) and diheptyltin (DHepT) were used as internal standards for quantification of volatile and semi-volatile organotin
compounds, respectively. The analytical precision (RSD) for ten successive injections of a standard mixture containing all
the organic tin compounds ranged between 2 and 11%. The limits of detection for all the organotin compounds were sub ng (Sn)
L−1 in water and close to ng (Sn) kg−1 in sediments. The accuracy of the method was evaluated by analysis of two certified reference material (CRM) sediment samples.
The HS-SPME–GC–PFPD was then applied to the analysis of three harbour sediment samples. The results showed that headspace
SPME is an attractive tool for analysis of organotin compounds in solid environmental matrices. 相似文献
16.
Bonnefoy C Menudier A Moesch C Lachâtre G Mermet JM 《Analytical and bioanalytical chemistry》2005,383(2):167-173
Quantification of chromium in whole blood has been performed by ICP–quadrupole MS. The spectrometer was equipped with a dynamic
reaction cell (DRC) with ammonia as reaction gas. The rejection parameter q (RPq) of the DRC and the flow rate of ammonia (NH3) were optimized and set at 0.7 and 0.6 mL min−1, respectively. Blood was diluted 1:51 (v/v) with an aqueous solution containing 0.1 mg L−1 NH4OH, 0.1 g L−1 EDTA, 5 mg L−1
n-butanol, and 0.1‰ Triton X100. Non-spectral matrix effects observed when using the DRC were confirmed by use of vanadium.
External calibration with blank and standard solutions prepared in purified water led to biased results for quality control
samples. Standard addition calibration was therefore used and its validity verified. By comparing the slopes and calculating
residues, it was proved that the plot obtained with standard additions and the plot obtained from blood samples of different
concentrations were aligned down to 0.05 μg L−1 after dilution. 相似文献
17.
Derivative of 8-hydroxyquinoline i.e. Clioquinol is well known for its antibiotic properties, drug design and coordinating
ability towards metal ion such as Copper(II). The structure of mixed ligand complexes has been investigated using spectral,
elemental and thermal analysis. In vitro anti microbial activity against four bacterial species were performed i.e. Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Bacillus substilis and found that synthesized complexes (15–37 mm) were found to be significant potent compared to standard drugs (clioquinol
i.e. 10–26 mm), parental ligands and metal salts employed for complexation. The kinetic parameters such as order of reaction
(n = 0.96–1.49), and the energy of activation (E
a = 3.065–142.9 kJ mol−1), have been calculated using Freeman–Carroll method. The range found for the pre-exponential factor (A), the activation entropy (S* = −91.03 to−102.6 JK−1 mol−1), the activation enthalpy (H* = 0.380–135.15 kJ mol−1), and the free energy (G* = 33.52–222.4 kJ mol−1) of activation reveals that the complexes are more stable. Order of stability of complexes were found to be [Cu(A4)(CQ)OH] · 4H2O > [Cu(A3)(CQ)OH] · 5H2O > [Cu(A1)(CQ)OH] · H2O > [Cu(A2)(CQ)OH] · 3H2O 相似文献
18.
A novel method combining matrix solid phase dispersion (MSPD) with Soxhlet simultaneous extraction clean-up (SSEC) was developed.
Being a single-step extraction and clean-up procedure, it could be used instead of multistep solvent extraction and Florisol
column clean-up. It not only reduces sample contamination during the procedure, but it also decreases the amount of organic
solvent needed. The retention times of standards were used to qualitatively assess the method, and the external standard method
was used to quantitatively assess it. Residues of organochlorine pesticides (OCP) in tobaccos were determined by gas chromatography–electron
capture detection (GC–ECD), and their identities were confirmed by the standard addition method (SAM). The performance of
the method was evaluated and validated: the detection limit was 0.01–0.02 μg g−1, relative standard deviations were 5–26%, and recoveries were 72–99% at fortification levels of 0.10, 1.00 and 10.0 μg g−1. The analytical characteristics of MSPD–SSEC compared very favorably with the results from the classical multistep solvent
extraction and Florisol column clean-up method. 相似文献
19.
Dian-Lei Wang Yan Liang Lin Xie Tong Xie X. T. Wang Sen Yu Guang-Ji Wang Xiao-Dong Liu 《Chromatographia》2008,67(3-4):219-224
To evaluate the pharmacokinetics of a novel analogue of ginkgolide B, 10-O-dimethylaminoethylginkgolide B (XQ-1) in rat plasma in pre-clinical studies, a sensitive and specific liquid chromatographic
method with electrospray ionization mass spectrometry detection (LC–ESI–MS) was developed and validated. After a simple extraction
with ethyl acetate, XQ-1 was analyzed on a Shim-pack C18 column with a mobile phase of a mixture of 1 μmol L−1 ammonium acetate containing 0.02% formic acid and methanol (55:45, v/v) at a flowrate of 0.3 mL min−1. Detection was performed in selected ion monitoring (SIM) mode using target ions at [M + H]+
m/z 496.05 for XQ-1 and m/z 432.10 for the internal standard (lafutidine). Linearity was established for the concentration range from 2 to 1,000 ng mL−1 . The extraction recoveries ranged from 86.0 to 89.9% in plasma at concentrations of 5, 50, and 500 ng mL−1. The lower limit of quantification was 2 ng mL−1 with 100 μL plasma. The validated method was successfully applied to a pharmacokinetic study after intragastic administration
of XQ-1 mesylate in rats at a dose of 20 mg kg−1. 相似文献
20.
Jing-Jing Deng Jian-Cheng Deng Zi-Ling Liu Hui-Ren Deng Bo Liu 《Journal of Solid State Electrochemistry》2009,13(9):1387-1394
Ni–Co oxide nanocomposite was prepared by thermal decomposition of the precursor obtained via a new method—coordination homogeneous
coprecipitation method. The synthesized sample was characterized physically by X-ray diffraction, scanning electron microcopy,
energy dispersive spectrum, transmission electron microscope, and Brunauer–Emmett–Teller surface area measurement, respectively.
Electrochemical characterization of Ni–Co oxide electrode was examined by cyclic voltammetry, galvanostatic charge–discharge,
and electrochemical impedance measurements in 6-mol L−1 KOH aqueous solution electrolyte. The results indicated that the addition of cobalt oxide not only changed the morphology
of NiO but also enhance its electrochemical capacitance value. A specific capacitance value of 306 F g−1 of Ni–Co oxide nanocomposite with n
Co = 0.5 (n
Co is the mole fraction of Co with respect to the sum of Co and Ni) was measured at the current density of 0.2 A g−1, nearly 1.5 times greater than that of pure NiO electrode. Lower resistance and better rate capability can also be observed. 相似文献