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1.
Protein can greatly enhance the fluorescence of curcumin (CU) in the presence of sodium dodecyl benzene sulfonate (SDBS).
Experiments indicate that under the optimum conditions, the enhanced intensity of fluorescence is proportional to the concentration
of proteins in the range of 0.0050–20.0 μg mL−1 for bovine serum albumin (BSA), 0.080–20.0 μg mL−1 for human serum albumin (HSA), and 0.040–28.0 μg mL−1 for egg albumin (EA). Their detection limits (S/N=3) are 1.4 ng mL−1, 20 ng mL−1, and 16 ng mL−1, respectively. The method has been satisfactorily used for the determination of proteins in actual samples. In comparison
with most of fluorimetric methods, this method is quick and simple, has high sensitivity and good stability. The interaction
mechanism is also studied. 相似文献
2.
Li C Wen D Zhang J Chen Z Cong W Rao Z Liu H 《Analytical and bioanalytical chemistry》2006,386(7-8):1985-1993
Metabolism of four tobacco-specific N-nitrosamines (TSNAs), N′-nitrosonornicotine (NNN), N′-nitrosoanatabine (NAT), N′-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been studied by solid-phase extraction
(SPE) and liquid chromatography–tandem mass spectrometry (LC–MS–MS). 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL)
was used as internal standard. SPE and LC–MS–MS was found to be a rapid, simple, sensitive, and selective method for analysis
of TSNAs in rabbit serum. The relative standard deviation (R.S.D., n = 6) for analysis of 5 ng mL−1 and 0.5 ng mL−1 standards and of serum sample spiked with 5 ng mL−1 standards of five TSNAs was 2.1–11% and recovery of 5 ng mL−1 standards from serum was 100.2–112.9%. A good linear relationship was obtained between peak area ratio and concentration
in the range of 0.2–100 ng mL−1 for NNAL and 0.5–100 ng mL−1 for other four TSNAs, with correlation coefficients (R
2) >0.99 (both linear and log–log regression). Detection limits for standards in solvent were between 0.04 and 0.10 ng mL−1. Doses of TSNAs administered to rabbits via the auricular vein were 4.67 μg kg−1 and 11.67 μg kg−1, in accordance with the different levels in cigarettes. Metabolic curves were obtained for the four TSNAs and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
(NNAL), a metabolite of NNK; on the basis of these curves we modeled metabolic kinetic equations for these TSNAs by nonlinear
curve fitting. 相似文献
3.
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
4.
Summary A reliable and sensitive high-performance liquid chromatographic method for the determination of the recent antidepressant
citalopram and two metabolites in human plasma has been developed. Fluorescence detection at 300 nm was used, exciting at
238 nm. Separation was obtained using a reversed-phase column (C18, 250 × 3.0 mm i.d., 5 μm) and a mobile phase. 40% acetonitrile:
60% aqueous tetramethylammonium perchlorate (pH 1.9). Calibration curves were linear over a working range: 5–300 ng mL−1 for citalopram, 2.5–150.0 ng mL−1 for desmethylcitalopram and 2.5–50.0 ng mL−1 for didesmethylcitalopram. The limits of quantitation (LOQ) were 1.5 ng mL−1 for citalopram and desmethylcitalopram and 2.0 ng mL−1 for didesmethylcitalopram. Precision data, as well as accuracy, were satisfactory and no interference from different psychotropic
drugs was found. The method was therefore suitable for therapeutic drug monitoring of citalopram and its active metabolites
in plasma of depressed patients. 相似文献
5.
Graziele P. Ramos Paula M. B. Dias Cláudia B. Morais Pedro E. Fröehlich Miguel Dall’Agnol José A. S. Zuanazzi 《Chromatographia》2008,67(1-2):125-129
Red clover (Trifolium pratense L.) is an important forage plant that contains the isoflavones daidzein, genistein, formononetin, and biochanin A. These
compounds have been studied lately due to their human health benefits. The aim of this study was to develop and validate an
HPLC method with simplified sample preparation to quantify daidzein, genistein, formononetin and biochanin A simultaneously
in red clover leaves. The validation showed that the method is specific, accurate, precise and robust, not to mention that
the sample preparation is easier and faster than those described earlier. The response was linear over a range of 0.01–0.2 μg mL−1 for daidzein, 0.05–0.5 μg mL−1 for genistein, 4–40 μg mL−1 for formononetin and 2–20 μg mL−1 for biochanin A. The range of recoveries was 85.6–101.0%. The RSD for intra- and inter-day precision were <2.54 and <7.22%,
respectively. Five populations of red clover, from the National Plant Germplasm System-USDA were analyzed and the content
of daidzein, genistein, formononetin and biochanin A ranged from 7.87–91.31, 51.60–131.30, 6568.33–23461.82, to 2499.55–10337.33 μg g−1 of dried material, respectively. 相似文献
6.
H. M. Lee C. K. Jeong S. J. Choi B. M. Yoon D. H. Na K. C. Lee H. S. Lee 《Chromatographia》2000,51(5-6):353-356
Summary An automated microbore, liquid chromatographic method with column-switching was developed for the determination of clomipramine
from human plasma samples. After direct injection of samples (60 μL), plasma proteins and clomipramine were separated in size-exclusion
mode using 20% acetonitrile in 20 mM phosphate buffer (pH 7.0) on Capcell Pak MF Ph-1 precolumn (10×4 mm I.D.). By valve switching,
a fraction containing clomipramine was directed to an intermediate column for subsequent main separation on a microbore C18 column (250×1.5 mm I.D.) using 50% acetonitrile in 20 mM phosphate buffer (pH 2.5) at 0.1 mL min−1. The method was advantageous for rapidity (total analysis time: 15 min), reproducibility (C.V.<4.8%), and increased sensitivity
(1 ng mL−1). The linearity of response was good (r
2≥0.999) over the concentration range 1–250 ng mL−1. 相似文献
7.
A high-performance liquid chromatography–UV method for determining DCJW concentration in rat plasma was developed. The method
described was applied to a pharmacokinetics study of intramuscular injection in rats. The plasma samples were deproteinized
with acetonitrile in a one-step extraction. The HPLC assay was carried out using a VP-ODS column and the mobile phase consisting
of acetonitrile–water (80:20, v/v) was used at a flow rate of 1.0 mL min−1 for the effective eluting DCJW. The detection of the analyte peak area was achieved by setting a UV detector at 314 nm with
no interfering plasma peak. The method was fully validated with the following validation parameters: linearity range 0.06–10 μg mL−1 (r > 0.999); absolute recoveries of DCJW were 97.44–103.46% from rat plasma; limit of quantification, 0.06 μg mL−1 and limit of detection, 0.02 μg mL−1. The method was further used to determine the concentration–time profiles of DCJW in the rat plasma following intramuscular
injection of DCJW solution at a dose of 1.2 mg kg−1. Maximum plasma concentration (C
max) and area under the plasma concentration–time curve (AUC) for DCJW were 140.20 ng mL−1 and 2405.28 ng h mL−1. 相似文献
8.
Determination of trace proteins with pyronine Y and SDS by resonance light scattering 总被引:1,自引:0,他引:1
A new resonance light scattering (RLS) probe for determining proteins is presented. The weak RLS of pyronine Y–SDS can be
enhanced substantially by adding proteins in the presence of H2SO4, resulting in a strong and wide RLS band in the region 310–425 nm. The interaction of pyronine Y–SDS with proteins was studied
on the basis of this behavior and a new quantitative method was developed for determining proteins. The enhanced RLS intensity
is proportional to the concentration of proteins in the range 0.15–3.6 μg mL−1 for bovine serum albumin (BSA) and 0.06–4.8 μg mL−1 for human serum albumin (HSA), with detection limits of 21.0 and 12.0 ng mL−1, respectively. This method is characterized by high sensitivity, rapidity of reaction, and simplicity. Four synthetic samples
were determined satisfactorily and recovery was 99.5–101.5%. Results for human serum and urine samples were in agreement with
those obtained by the Bradford method, with relative standard deviations (RSD) of 1.5–3.1%. 相似文献
9.
Schettgen T Tings A Brodowsky C Müller-Lux A Musiol A Kraus T 《Analytical and bioanalytical chemistry》2007,387(8):2783-2791
Analysis of biomarkers in exhaled breath condensate (EBC) is a non-invasive method for investigating the effects of different
diseases or exposures, on the lungs and airways. N
ɛ-carboxymethyllysine (CML) is an important biomarker of advanced glycation end products (AGEs). A method has been developed
for simultaneous determination of CML and its precursor, the amino acid lysine, in exhaled breath condensate (EBC). After
addition of labelled internal standards (d-4-CML; d-4-lysine), the EBC was concentrated by freeze-drying. Separation and detection
of the analytes were performed by hydrophilic-ion liquid chromatography coupled with tandem mass-spectrometric detection (HILIC–MS–MS).
The limits of quantification were 10 pg mL−1 EBC and 0.5 ng mL−1 EBC for CML and lysine, respectively. The relative standard deviation of the within-series precision was between 2.8 and
7.8% at spiked concentrations between 40 and 200 pg mL−1 for CML and between 6 and 20 ng mL−1 for lysine. Accuracy for the analytes ranged between 89.5 and 133%. The method was used for the analysis of EBC samples from
ten healthy persons from the general population and ten persons receiving dialysis. CML and lysine were detected in all EBC
samples with median values of 19 pg mL−1 CML and 11.9 ng mL−1 lysine in EBC of healthy persons and 25 pg mL−1 CML and 9.5 ng mL−1 lysine in EBC of dialysis patients. 相似文献
10.
M. A. Raggi C. Sabbioni V. Pucci N. Ghedini N. Calonghi G. Gerra 《Chromatographia》2001,53(7-8):409-413
Summary This study deals with the development of a new HPLC method for the determination of 3-methoxy-4-hydroxyphenylglycol (MHPG),
the main noradrenaline metabolite in human plasma. A Varian reversed-phase column (C8; 250 mm×4.6 mm i.d.; 5 μm particles) was used as the stationary phase and an aqueous solution of citric acid, 1-octanesulfonic
acid, EDTA, and methanol was used as the mobile phase. Coulometric electrochemical detection (ED) was used to obtain the highest
sensitivity. Isolation of MHPG from plasma was accomplished by means of a new solid-phase extraction procedure after a protein
precipitation step. The extraction yield of MHPG from plasma was very high (>97%). Linearity was observed in the 0.5–25 ng
mL−1 concentration range; the limit of detection was 0.2 ng mL−1 and the limit of quantitation was 0.5 ng mL−1. Repeatability (RSD,%) for plasma samples was found to be <3.2% and intermediate precision was <4.3%. The method was applied to the determination
of MHPG in the plasma of healthy subjects under experimentally-induced psychological stress. 相似文献
11.
A convenient, selective and sensitive liquid chromatographic-electrospary ionization mass spectrometry (LC–ESI–MS) method
was developed and validated to determine lovastatin in human plasma. The analyte was extracted from human plasma samples by
typical liquid–liquid extraction, separated on a C18 column by using the mobile phase consisting of water–methanol (13:87, v/v). Simvastatin was used as the internal standard (IS). The method was linear within the range of 0.1–20 ng mL−1. The lower limit of quantification (LLOQ) was 0.1 ng mL−1. The intra- and inter-run precision, calculated from quality control (QC) samples was less than 10.2%. The accuracy as determined
from QC samples was in the range of 99.3–102.9% for the analyte. The mean recoveries for lovastatin and IS were 84.8 and 88.0%,
respectively. The method was successfully applied for evaluation of the pharmacokinetic of lovastatin in healthy volunteers. 相似文献
12.
Study of a toxin–alkaline phosphatase conjugate for the development of an immunosensor for tetrodotoxin determination 总被引:2,自引:0,他引:2
This paper describes a direct competitive immunoenzymatic spectrophotometric assay (ELISA) for tetrodotoxin (TTX) determination
and the adaptation of this method for use in an electrochemical assay format. The novelty of this work involves the use of
the antigen labelled with alkaline phosphatase (AP); this conjugate was prepared in our laboratory as there is no commercially
available conjugate of any kind for TTX. The new conjugate was characterized in terms of its affinity for the specific antibody
as well as the residual concentration and the residual activity of the enzyme (AP) incorporated as label. The proposed method
based on the new conjugate showed satisfactory results for TTX determination: for the spectrophotometric method the dynamic
range was 4–15 ng mL−1 with a limit of detection (LOD) of 2 ng mL−1 (R=0.9247), whereas for the electrochemical protocol the dynamic range was 2–50 ng mL−1 and the LOD was1 ng mL−1. 相似文献
13.
Neng Zhou Yi-Zeng Liang Ben-Mei Chen Ping Wang Xian Chen Feng-Ping Liu 《Chromatographia》2007,66(7-8):481-486
A rapid, simple and specific liquid chromatography-electrospray ionization mass spectrometry method has been developed and
validated for the determination of hydroxyzine hydrochloride in human plasma. Samples were separated using a Thermo Hypersil-HyPURITYC18
reversed-phase column (150 mm × 2.1 mm i.d., 5 μm). The mobile phase consisted of 50 mM ammonium acetate (pH 4.0)–methanol–acetonitrile
(45:36:19, v/v). Hydroxyzine and its internal standard were measured by electrospray ion source in positive selective ion monitoring mode.
The method was validated with a linear range of 1.56–200.0 ng mL−1 and the lowest limit of quantification was 1.56 ng mL−1 for hydroxyzine hydrochloride (r
2= 0.9991). The extraction efficiencies were about 70% and recoveries of the method were in the range of 93.5–104.4%. The intra-day
relative standard deviation (RSD) was less than 8.0% and inter-day RSD was within 7.4%. QC samples were stable when kept at
ambient temperature for 12 h at −20 °C for 30 days and after four freeze–thaw cycles. The method has been successfully applied
to the evaluation of pharmacokinetics and bioequivalence of two hydroxyzine hydrochloride formulations in 12 healthy Chinese
volunteers after an oral dose of 25 mg. 相似文献
14.
A rapid and simple high performance liquid chromatographic method coupled with tandem mass spectrometry (LC–MS–MS) via electrospray
ionization (ESI) has been developed and validated to separate and simultaneously quantify sodium ferulate (SF), salicylic
acid (SA), cinnarizine (CIN) and vitamin B1 (VB1) in human plasma. Gemfibrozil (GEM) was used as the internal standard (IS)
for SF and SA, whereas lomerizine (LOM) was used as the IS for CIN and VB1. The plasma samples were prepared by one-step protein
precipitation followed by an isocratic elution with 10 mM ammonium acetate buffer (pH = 5.0): acetonitrile (35:65, v/v,) on an Agilent Zorbax SB-CN column (150 mm × 2.0 mm ID, 5 μm). The precursor and product ions of these drugs were monitored
on a triple quadrupole mass spectrometer, operating in the selected reaction monitoring mode (SRM) with polarity switch, in
the negative-ion mode for SF, SA and GEM, in the positive-ion mode for CIN, VB1 and LOM. The method was validated over the
concentration range of 1.5–1,000 ng mL−1 for SF, 20–5,000 ng mL−1 for SA, 2–500 ng mL−1 for CIN, 1–30 ng mL−1 for VB1. The intra- and inter-batch precisions were less than 15% of the relative standard deviation. The recoveries for
analytes and IS achieved from spiked plasma samples were consistent and reproducible. The validated LC–MS–MS method has been
successfully applied to the pharmacokinetic study of sodium ferulate and aspirin capsule in healthy volunteers. 相似文献
15.
Summary A method for the determination of 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methylsuccinimide (2-HMSI) in
plasma was developed. 5-HNMP and 2-HMSI are metabolites to the widely used organic solvent N-methyl-2pyrrolidone (NMP). The
5-HNMP and 2-HMSI were purified from plasma by C8 solid phase extraction, derivatised by bistrimethylsilyl trifluoroacetamid,
and analysed by gas chromatography with mass spectrometric detection. For 5-HNMP, the precision was 2–7 % (120 and 780 ng
mL−1) and the detection limit was 6 ng mL−1 (m/z 98). For 2-HMSI, the precision was 2–9 % (160 and 1000 ng mL−1) and the detection limit was 4 ng mL−1 (m/z 144). The method is applicable for analysis of plasma samples from workers exposed to NMP. 相似文献
16.
A simple, rapid, and highly sensitive spectrofluorimetric method for the determination of acitretin was developed based on
the strong green fluorescence of acitretin. Influence of organic solvents on the fluorescence spectra of acitretin was studied.
Effects of pH, standing time, and foreign ions on the determination of acitretin were also examined. Under the optimum conditions,
linear relationship between the relative fluorescence intensity and the concentration of acitretin in the range of 30.0–1100
ng mL−1 was obtained. Detection limit of this method is 9.56 ng mL−1 for acitretin. Relative standard deviation for the determination of 480 ng mL−1 of acitretin was 1.70 %. This method was used for the determination of acitretin in pharmaceuticals and the results were
compared with those obtained by the HPLC method. 相似文献
17.
Haiyang Jiang Shuangyang Ding Fei Xu Sijun Zhao Jihong He Jinfeng Liu Xiaolin Hou Jianzhong Shen 《Chromatographia》2007,66(5-6):411-414
Eprinomectin is a novel and potent antiparasitic animal health drug. An analytical procedure for the determination of EPR
in bovine urine and feces has been developed. The urine sample was centrifuged and alkalized with ammonia following solid
phase extraction. The fecal sample was extracted with acetonitrile, defatted with hexane, cleaned-up using C18 cartridge.
All samples were analyzed by high performance liquid chromatography with fluorescence detection after derivatization with
N-methylimidazole. The limits of detection are 0.5 ng mL−1 and 0.5 ng g−1, respectively. Fortified at 2, 10, 50, and 100 ng mL−1(ng g−1), inter-assay recoveries of EPR in cattle urine and feces were in the range of 87.9–91.5% and 78.6–86.3%, with coefficients
of variation of 5.4–10.2% and 1.4–7.2%, respectively. Intra-assay mean recoveries of the analytes were 82.2–86.5% and 79.6–87.3%,
with coefficients of variation of 7.8–11.5% and 6.3–7.8%, respectively. The method was used to study the excretion of eprinomectin
in bovine urine and feces after subcutaneous administration at a dose of 0.5 mg kg−1. 相似文献
18.
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
19.
Ródenas-Torralba E Morales-Rubio A de la Guardia M 《Analytical and bioanalytical chemistry》2005,383(1):138-144
An automated and greener spectrophotometric procedure has been developed for the determination of phenol in water at 700 nm.
The method uses the reaction between phenol, sodium nitroprusside, and hydroxylamine hydrochloride in a buffered medium at
pH 12.3. The flow manifold comprises four solenoid micro-pumps employed for sample and reagent introduction into the reaction
coil and to transport the colored product formed to the detector. The linear dynamic range was 50–3,500 ng mL−1 (R = 0.99997; n = 6) and the method provided a limit of detection (3σ) of 13 ng mL−1. The sampling throughput was estimated to be 65 measurements per hour and the coefficient of variation was 0.5% (n = 10) for a 1.0 μg mL−1 phenol concentration. Recoveries of 92–105% were obtained for phenol determination in spiked water samples at concentration
levels from 50 to 5,000 ng mL−1. The use of multicommutation reduced the reagent consumption 25-fold, the sample consumption 225-fold, and the waste generation
30-fold compared with the batch procedure. The proposed method is an environmentally friendly alternative to the official
4-aminoantipyrine method since it avoids the use of chloroform. 相似文献
20.
Summary A rapid, sensitive and selective high-performance liquid chromatographic method has been developed for the determination of
sphingosine in human serum. After precipitation with methanol, the samples were extracted using Carbopack B disposable columns;
the sphingosine was eluted with 0.05 M hydrochloric acid in methanol-dichloromethane (20∶80, v/v) and the extract evaporated
to dryness at 40°C. The sample residue was then reconstituted with methanol and reacted with o-phthaldialdehyde reagent to
produce a fluorescent compound. Separation was performed using an LC-18 column with 0.05 M phosphate buffer (pH 7)-methanol-acetonitrile
(15∶80∶5, v/v) as mobile phase. Fluorescence detection was performed with excitation and emission wavelengths of 340 and 455
nm, respectively. The serum extract was re-analyzed with a cyano LC column to minimize the possibility of false positive results.
The possible interference of compounds having a structure similar to that of sphingosine was evaluated. The mean recovery
of sphingosine was >94.5%. The limit of detection of the assay was 1 ng mL−1. The between-run and within-run coefficients of variation for replicate analyses were <4.0% and <3.4%, respectively. The
levels of free sphingosine in the serum of 40 normal subjects (20 male and 20 female) was investigated; the average level
was 81.6±41.1 ng mL−1 (mean ±S.D.) for males and 85.5±33.7 ng mL−1 for females. 相似文献