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1.
Spin‐labeled nitroxide derivatives of podophyllotoxin had better antitumor activity and less toxicity than that of the parent compounds. However, the 2‐H configurations of these spin‐labeled derivatives cannot be determined by nuclear magnetic resonance (NMR) methods. In the present paper, a high‐performance liquid chromatography‐diode array detection (HPLC‐DAD) and a high‐performance liquid chromatography‐electrospray ionization tandem mass spectrometry (HPLC‐ESI/MS/MS) method were developed and validated for the separation, identification of four pairs of diastereoisomers of spin‐labeled derivatives of podophyllotoxin at C‐2 position. In the HPLC‐ESI/MS spectra, each pair of diastereoisomers of the spin‐labeled derivatives in the mixture was directly confirmed and identified by [M+H]+ ions and ion ratios of relative abundance of [M‐ROH+H]+ (ion 397) to [M+H]+. When the [M‐ROH+H]+ ions (at m/z 397) were selected as the precursor ions to perform the MS/MS product ion scan. The product ions at m/z 313, 282, and 229 were the common diagnostic ions. The ion ratios of relative abundance of the [M‐ROH+H]+ (ion 397) to [M+H]+, [A+H]+ (ion 313) to [M‐ROH+H]+, [A+H‐OCH3]+ (ion 282) to [M‐ROH+H]+ and [M‐ROH‐ArH+H]+ (ion 229) to [M‐ROH+H]+ of each pair of diastereoisomers of the derivatives specifically exhibited a stereochemical effect. Thus, by using identical chromatographic conditions, the combination of DAD and MS/MS data permitted the separation and identification of the four pairs of diastereoisomers of spin‐labeled derivatives of podophyllotoxin at C‐2 in the mixture.  相似文献   

2.
Monoamines, acting as hormones and neurotransmitters, play a critical role in multiple physiological processes ranging from cognitive function and mood to sympathetic nervous system activity, fight‐or‐flight response and glucose homeostasis. In addition to brain and blood, monoamines are abundant in several tissues, and dysfunction in their synthesis or signaling is associated with various pathological conditions. It was our goal to develop a method to detect these compounds in peripheral murine tissues. In this study, we employed a high‐performance liquid chromatography method using electrochemical detection that allows not only detection of catecholamines but also a detailed analysis of nine monoamines and metabolites in murine tissues. Simple tissue extraction procedures were optimized for muscle (gastrocnemius, extensor digitorum longus and soleus), liver, pancreas and white adipose tissue in the range of weight 10–200 mg. The system allowed a limit of detection between 0.625 and 2.5 pg μL−1 for monoamine analytes and their metabolites, including dopamine, 3,4‐dihydroxyphenylacetic acid, 3‐methoxytyramine, homovanillic acid, norepinephrine, epinephrine, 3‐methoxy‐4‐hydroxyphenylglycol, serotonin and 5‐hydroxyindoleacetic acid. Typical concentrations for different monoamines and their metabolization products in these tissues are presented for C57Bl/6 J mice fed a high‐fat diet.  相似文献   

3.
Detecting pesticide residues in human serum is a challenging process. In this study we developed and validated a method for the extraction and recovery of residues of multiple classes of pesticides from serum using one reagent. Salt‐assisted acetonitrile extraction and high‐performance liquid chromatography with quadrupole time of flight tandem mass spectrometry were used to quantitate 34 pesticides classified in nine groups of chemicals in human serum samples, which are frequently detected in food. The recoveries for 33 of analyzed pesticides ranged from 86 to 112% with relative standard deviations below 15%. The limits of quantitation and linearity of 31 of the pesticides were 1 µg/L and >0.990, respectively. The lower limit of quantitation has been reported in the literature particularly for multi‐classes pesticide mixtures in human serum. The salt–acetonitrile reagent was allowed to achieve good recoveries and detection limits, which could be attributed to salt altering the solvent polarity, preferentially collecting the organic phase in the solution, and promoting the extraction. The developed method was applied for two organophosphate pesticide metabolites, diethylphosphate and 3,5,6‐trichloro‐2‐pyridinol, in serum from rats that were fed a nonlethal quantity of chlorpyrifos. The concentrations of these two were 252.18 ± 15.47 and 0.63 ± 0.23 µg/L, respectively.  相似文献   

4.
A residual determination method as a regulatory residue method was developed using HPLC‐UVD for prohexadione residues in Chinese cabbage (Brassica pekinensis) and apple (Malus domestica). The developed method consisted of solid–liquid extraction with acidic acetonitrile and ion‐suppression liquid–liquid partitioning, followed by anion exchange cartridge cleanup. The limits of detection and quantitation for the method were 0.005 and 0.02 mg/kg, respectively. The method gave good linearity in the range of 0.02–2.5 mg/kg. Accuracy and precision ranged from 84.1 to 94.1% and from 2.4 to 6.9%, respectively. Additionally, the confirmative conditions of LC‐MS/MS for prohexadione were set in negative electrospray ionization mode with transitions of m/z 211.4 → 167.5 and m/z 211.4 → 123.5 in the selected reaction monitoring mode. The applicability of the method was demonstrated by analyzing real samples collected from local markets in Seoul, Republic of Korea. This developed method fully deserves consideration in accordance with its sensitivity, accuracy and precision required for residue analysis of prohexadione in Chinese cabbages and apples. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

5.
Psoralea Corylifolia L. is a traditional Chinese medicine with many beneficial effects in medical therapies. Bakuchiol was the main active ingredient of Psoralea Corylifolia L., used for the treatment of various diseases and also as a natural food additive. A specific and reliable ultra‐high performance liquid chromatography–tandem mass spectrometry has been developed and fully validated for the quantification of bakuchiol in rat plasma. Chromatographic separation of bakuchiol and an internal standard, daidzein, was achieved on a Hypersil Gold C18 column with gradient elution that consisted of methanol and water at a flow rate of 0.2 mL/min. The compounds were detected at negative ionization mode using mass transition m/z 255.2 → 172.0 and 252.9 → 132.0 for bakuchiol and daidzein, respectively. Good linearity was obtained over the range of 2–1000 ng/mL and the lower limit of quantification was 2 ng/mL. The intra‐ and inter‐day accuracies ranged from 91.1 to 105.7% and precisions (relative standard deviations) were within 9.3%. Bakuchiol was found to be stable under three freeze–thaw cycles, short‐term temperature, post‐preparative and long‐term temperature conditions. The method was applied to a pharmacokinetic study of bakuchiol intravenously administered to rats at a dose of 5 mg/kg. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

6.
A simple and sensitive method based on the combination of solid‐phase microextraction (SPME) and high‐performance liquid chromatography with ultroviolet detection was developed for the simultaneous determination of clenbuterol, salbutamol and ractopamine in pig samples. Parameters of the SPME procedure affecting extraction efficiency, such as the type of fiber, extraction time, extraction temperature, ion strength, pH of sample and stirring rate, were optimized. The developed method was validated according to the International Conference on Harmonization guidelines. The calibration curves were linear over a range of 0.5–50 µg/L for clenbuterol and ractopamine, and 0.2–20 µg/L for salbutamol. The limits of detection were 0.1 µg/L for clenbuterol, 0.05 µg/L for salbutamol and 0.1μg/L for ractopamine, respectively. The averages of intra‐ and inter‐day accuracy ranged from 79.8 to 92.4%. The intra‐day and inter‐day precision were below 9.6% for the three analytes. This method exhibited the advantages of simplicity, rapidity and low solvent consumption, and was suitable for the monitoring of β2‐agonists residue in pig samples. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

7.
A sensitive and specific method was developed and validated for the quantitation of one major metabolite of genipin in rats plasma. The major metabolite was isolated from rat bile via semi‐preparative HPLC technology and its chemical structure was identified as genipin‐1‐o‐glucuronic acid (GNP‐GLU), which was for the first time used as a standard compound for quantitative analysis in rat plasma after administration of genipin. The application of high‐performance liquid chromatography–tandem mass spectrometry in negative mode in multiple reaction monitoring mode was investigated. Chromatographic separation was achieved on an Eclipse XDB‐C18 column using a mobile phase consisting of water with 0.1% formic acid (A)–acetonitrile (B). The limit of detecation was 0.214 ng/mL and the lower limit of quantification was 0.706 ng/mL. The calibration curve was linear from 1.27 to 3810 ng/mL for plasma samples, with a correlation coefficient of 0.9924. The intra‐ and inter‐day precisions and accuracy were all within 15%. The recoveries of GNP‐GLU and puerarin were above 90.0 and 76.2%, respectively. The highly sensitive method was successfully applied to estimate pharmacokinetic parameters of GNP‐GLU following oral and intravenous administration of genipin to rats. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

8.
Tricaine methanesulfonate is one of most commonly used anesthetics in fish during blood sampling, artificial propagation and long‐distance transportation. In this study, an accurate method for the quantitative determination of tricaine in fish samples by a stable isotope dilution assay coupled with high‐performance liquid chromatography–triple quadrupole mass spectrometry was developed. Tricaine‐D5 was synthesized and used as an isotopically labeled internal standard for the determination of tricaine. The analytical performance of the method was validated for tricaine determination in marine fish and freshwater fish. The determination of tricaine was linear in the range of 2.0–200.0 μg L?1. The limit of detection and limit of quantitation for fish muscle tissues were 1.0 and 4.0 μg kg?1, respectively. Good recoveries were obtained in the range of 92.08–97.50%. The inter‐ and intra‐assay relative standard deviations (RSD values) were investigated, and the values were 0.39–3.01 and 0.85–2.77%, respectively. The values of CCα and CCβ were 10.21–10.43 and 10.42–10.87 μg kg?1, respectively. The clearance of MS‐222 from grass carp was further studied using our method. The results demonstrate that MS‐222 could be well absorbed and rapidly eliminated after bath administration.  相似文献   

9.
The purine metabolic pathway has been implicated in neurodegeneration and neuroprotection. High‐performance liquid chromatography (HPLC) is widely used to determine purines and metabolites. However, methods for analysis of multiple purines in a single analysis have not been standardized, especially in brain tissue. We report the development and validation of a reversed‐phase HPLC method combining electrochemical and UV detection after a short gradient run to measure seven purine metabolites (adenosine, guanosine, inosine, guanine, hypoxanthine, xanthine and urate) from the entire purine metabolic pathway. The limit of detection (LoD) for each analyte was determined. The LoD using UV absorption was 0.001 mg/dL for hypoxanthine (Hyp), inosine (Ino), guanosine (Guo) and adenosine (Ado), and those using coulometric electrodes were 0.001 mg/dL for guanine (Gua), 0.0001 mg/dL for urate (UA) and 0.0005 mg/dL for xanthine (Xan). The intra‐ and inter‐day coefficient of variance was generally <8%. Using this method, we determined basal levels of these metabolites in mouse brain and serum, as well as in post‐mortem human brain. Peak identities were confirmed by enzyme degradation. Spike recovery was performed to assess accuracy. All recoveries fell within 80–120%. Our HPLC method provides a sensitive, rapid, reproducible and low‐cost method for determining multiple purine metabolites in a single analysis in serum and brain specimens. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

10.
In the present study, dispersive liquid–liquid microextraction followed by high performance liquid chromatography‐diode array detection has been developed as simple, rapid, accurate, and efficient sample preparation method for simultaneous determination of seven organic UV filters in urine samples. The influence of the main effects as well as their interactions was studied through a 2(6–2) fractional factorial design. The candidate parameters were: type and volume of dispersant and extraction solvents, sample pH, and salt concentration. Under final optimal conditions, the analytes were extracted from 5 mL of samples by addition of 0.5 mL of acetonitrile (dispersing solvent) containing 70 μL of carbon tetrachloride (extraction solvent), without modifying the pH of the solution and applying the (+1) level of salt concentration (10% w/v NaCl). The assay was linear (R2 > 0.997), relative recoveries ranged from 86.9 up to 97.3% and the LOQs between 3 and 45 ng mL?1 were obtained. The intra‐ and interday RSDs were lower than 5 and 8% at the middle point of the linear range, respectively. The proposed method was successfully applied to different volunteer urine samples and it was shown that the extraction efficiency was not affected by the type of urine samples.  相似文献   

11.
The speciation of chromium(VI) and chromium(III) was investigated by using hollow fiber liquid‐phase microextraction based on two immiscible organic solvents followed by high performance liquid chromatography with ultraviolet detection. In this method, chromium(VI) and chromium(III) reacted with ammonium pyrrolidine dithiocarbamate to produce hydrophobic complexes. Subsequently, the complexes were first extracted into a thin layer of organic solvent (n‐dodecane) present in the pores of a porous hollow fiber, and then into a μL volume of an organic acceptor (methanol) located inside the lumen of the hollow fiber. Then, the extracting organic phase was injected into the separation column of the high‐performance liquid chromatograph for the analysis of both chromium species. Effective parameters on extraction were optimized using one‐variable‐at‐a‐time method and central composite design. Under optimized conditions, a linear range of 0.25–100 and 0.5–100 μg/L (R 2 > 0.998), the limits of detection of (S/N = 3) 0.08 and 0.1 μg/L and a preconcentration factor of 625 and 556 were achieved for chromium(VI) and chromium(III), respectively. The method was successfully applied to the speciation and determination of chromium species in different water samples and satisfactory results were obtained.  相似文献   

12.
Febuxostat is a novel nonpurine type of highly selective xanthine oxidoreductase inhibitor. A rapid and sensitive ultra‐high‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry method for simultaneous separation and determination of febuxostat and its metabolites in rat serum and urine was developed at various time points after oral administration to the rats. The febuxostat metabolites were predicted by biotransformation software and transformed to a personal compound database to quickly determine the possible metabolites from the MS1 data. The possibility of the MS/MS fragmentation was calculated by the Molecular Structure Correlator software. As a result, five phase I and two phase II metabolites in rat serum, and seven phase I and three phase II metabolites in rat urine were identified, of which four metabolites (M2, M5, M6, M7) have not been reported before. The metabolite toxicities are predicted, and the results are helpful for the design of new xanthine oxidoreductase inhibitors.  相似文献   

13.
Glucocorticoids are a mainstay for the treatment of immune‐mediated conditions and inflammatory diseases. However, their chronic use causes numerous side‐effects including delays in corneal and cutaneous wound healing. This is attributed to off‐target agonism of the mineralocorticoid receptor, which can be reduced by co‐administration of a mineralocorticoid receptor antagonist such as spironolactone. The aim of this study was to develop a fast, selective and sensitive UHPLC‐ESI‐MS method for the simultaneous quantification of spironolactone, its active metabolites (7α‐thiomethylspironolactone and canrenone), the latter's water‐soluble prodrug potassium canrenoate and the synthetic glucocorticoid, dexamethasone, in corneal samples (17α‐methyltestosterone served as an internal standard). A one‐step extraction procedure using MeOH–H2O (1:1) was validated and employed to recover the analytes from the corneal tissue. Extracts were centrifuged and the supernatant analyzed under isocratic conditions. Compounds were detected using selected ion recording mode. The method satisfied US Food and Drug Administration guidelines with respect to selectivity, precision and accuracy and displayed linearity from 5 to 1000 ng/mL for all of the analytes. The lower limit of quantitation of the method was 5 ng/mL, making it sufficiently sensitive for quantification of the analytes in samples from in vivo studies.  相似文献   

14.
Curcumin, derived from turmeric, has been extensively investigated for its broad spectrum of biological activities. Previously reported HPLC‐UV methods have focussed on analysis of the parent compound. Here, a sensitive HPLC‐UV method was developed and partially validated, then used for the simultaneous determination of curcumin and its glucuronide and sulfate metabolites in plasma and lung tissue from mice. The assay was applied to an in vivo pharmacokinetic study comparing formulated curcumin (Meriva™) with standard curcumin. Plasma levels of glucuronide and sulfate metabolites were 5‐ and 2‐fold higher after Meriva™ administration compared with standard curcumin. In lung tissue, free curcumin was 4‐fold higher following Meriva™ administration vs standard curcumin. This assay represents a rapid, cheap method for simultaneous detection of curcumin and its major metabolites that has applicability in pre‐clinical settings.  相似文献   

15.
A sensitive and specific ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC‐MS‐MS) method for quantification of a newly developed anticancer agent NPD‐103 has been established. An aliquot of human plasma sample (200 µL) was spiked with 13C‐labeled paclitaxel (internal standard) and extracted with 1.3 mL of tert‐butyl methyl ether. NPD‐103 was quantitated on a C18 column with methanol–0.1% formic acid (75:25, v/v) as mobile phase using UPLC‐MS‐MS operating in positive electrospray ionization mode with a total run time of 3.0 min. For NPD‐103 at the concentrations of 1.0, 5.0 and 10.0 µg/mL in human plasma, the absolute extraction recoveries were 95.58, 102.43 and 97.77%, respectively. The linear quantification range of the method was 0.1–20.0 µg/mL in human plasma with linear correlation coefficients greater than 0.999. The intra‐ and inter‐day accuracy for NPD‐103 at 1.0, 5.0 and 10.0 µg/mL levels in human plasma fell into the ranges of 95.29–100.00% and 91.04–94.21%, and the intra‐ and inter‐day precisions were in the ranges of 8.96–11.79% and 7.25–10.63%, respectively. This assay is applied to determination of half‐life of NPD‐103 in human plasma. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

16.
Determination of amino acids in biofluids is a challenging task because of difficulties deriving from their high polarity and matrix interference. A simple, reliable and high‐throughput hydrophilic interaction UHPLC–MS/MS method was developed and validated for the rapid simultaneous determination of 19 free amino acids in rat plasma and urine samples in this paper. Hydrophilic method with a Waters Acquity UPLC BEH Amide column (100 × 2.1 mm,1.7 μm) was used with a gradient mobile phase system of acetonitrile and water both containing 0.2% formic acid. The analysis was performed on a positive electrospray ionization mass spectrometer via multiple reaction monitoring. Samples of 10 μL plasma and 50 μL urine were spiked with three deuterated internal standards, pretreated with 250 μL acetonitrile for one‐step protein precipitation and a final dilution of urine samples. Good linearities (r > 0.99) were obtained for all of the analytes with the lower limit of quantification from 0.1 to 1.2 μg/mL. The relative standard deviation of the intra‐day and inter‐day precisions were within 15.0% and the accuracy ranged from ?12.8 to 12.7%. The hydrophilic interaction UHPLC–MS/MS method was rapid, accurate and high‐throughput and exhibited better chromatography behaviors than the regular RPLC methods. It was further successfully applied to detect 19 free amino acids in biological matrix.  相似文献   

17.
Herein, a new dispersive solid‐phase extraction method using a nano magnetic titanium dioxide graphene‐based sorbent in conjunction with high‐performance liquid chromatography and ultraviolet detection was successfully developed. The method was proved to be simple, sensitive, and highly efficient for the trace quantification of sulfacetamide, sulfathiazole, sulfamethoxazole, and sulfadiazine in relatively large volume of aqueous media. Initially, the nano magnetic titanium dioxide graphene‐based sorbent was successfully synthesized and subsequently characterized by scanning electron microscopy and X‐ray diffraction. Then, the sorbent was used for the sorption and extraction of the selected sulfonamides mainly through π–π stacking hydrophobic interactions. Under the established conditions, the calibration curves were linear over the concentration range of 1–200 μg/L. The limit of quantification (precision of 20%, and accuracy of 80–120%) for the detection of each sulfonamide by the proposed method was 1.0 μg/L. To test the extraction efficiency, the method was applied to various fortified real water samples. The average relative recoveries obtained from the fortified samples varied between 90 and 108% with the relative standard deviations of 5.3–10.7%.  相似文献   

18.
Flavonoids in Calligonum polygonoides Linnaeus extract were separated, detected, and identified by reverse‐phase high‐performance liquid chromatography (RP‐HPLC) with electrochemical detection (EC) in combined isocratic and gradient elution using a glassy carbon or a boron doped diamond electrode. Ultrasonication coupled with a microwave‐assisted technique was developed to optimize the extraction of the phenolic compounds. The total antioxidant capacity was quantified using the DPPH. method and voltammetry. The RP‐HPLC‐EC led to the detection of nine different flavonoids: catechin, delphinidin, fisetin, myricetin, epicatechin, kuromanin, rutin, callistephin and procyanidin A2, in a single run by direct injection of the sample extract solution.  相似文献   

19.
A vortex‐assisted liquid–liquid micro‐extraction coupled with high‐performance liquid chromatography, with UV–vis, is proposed to pre‐concentrate methyl methacrylate and to improve separation in biological matrices. The use of 1‐octanol as extracting phase, its volume, the need for a dispersant agent, the agitation conditions and the cooling time before phase separation were evaluated. In optimum conditions, enrichment factors of 20 (±0.5) and enrichment recovery of 99% were obtained. The straightforward association of this extraction process with the HPLC method, previously regulated by the International Organization for Standardization, afforded a detection limit of 122 ng/mL and a quantification limit of 370 ng/mL. The within‐batch precision, relative standard deviation, was 3% for a sample with 1.49 µg/mL and 4% for a sample with 13.4 µg/mL. The results showed a between batch‐precision of 21% for experiments performed on five different days, for a sample with a concentration of 1.10 µg/mL in methyl methacrylate. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

20.
A method based on direct immersion solid‐phase microextraction (DI‐SPME) coupled with high performance liquid chromatography combined with post‐column photochemically induced fluorimetry derivatization and fluorescence detection (HPLC‐PIF‐FD) was developed to extract three pyrethroid insecticides, i.e. cyfluthrin, cypermethrin, and flumethrin from water samples. A sol‐gel based coating fiber using 3‐(trimethoxysilyl propyl) amine as precursor was prepared and used for the extraction of the pyrethroids from groundwater samples. A post‐column photochemical reactor was designed and constructed for the derivatization of these environmentally important pollutants to increase their fluorescence sensitivity and determination in HPLC. The parameters affecting extraction process (extraction time and temperature, pH, salt addition, and co‐solvent) and desorption step (solvent, desorption time, and temperature) of the analytes from the sol‐gel‐based fiber, along with photochemical reaction conditions were investigated. The developed method proved to be relatively rapid, simple, and easy and offers high sensitivity and reproducibility. Linear dynamic ranges (LDR) for these insecticides were ranged between 0.25 to 50 μg/L. The regression coefficients were satisfactory (R2 > 0.984) for these pyrethroids. The limits of detection and limits of quantification varied between 0.09 and 0.35 μg/L and 0.25 and 1.00 μg/L, respectively. Relative standard deviation RSDs values varied between 4.41% and 6.20%. Relative recoveries obtained from analysis of Jajroud river water sample ranged between 94% and 104%.  相似文献   

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