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1.
Anal Chim Acta ; 1105: 224-230, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32138922

RESUMO

An on-line cyclodextrin assisted sweeping-micellar electrokinetic chromatography (CD assisted sweeping-MEKC) was developed for the simultaneous separation and concentration of four neutral analytes (erianin, dendrophenol, naringenin and scoparone) in Dendrobium officinale Kimura et Migo (D. officinale). The D. officinale was directly determined by this on-line stacking method after simple extraction and dilution. The optimized background solution (BGS) was 50 mM phosphoric acid (PA) containing 100 mM SDS and 30% (v/v) methanol. The best separation and concentration performance of analytes dissolved in 90 mM CD and 100 mM PA was achieved in a short analysis time when injected at 50 mbar for 100 s. Compared with conventional sweeping-MEKC and MEKC method, significant improvement in enrichment efficiency was achieved by using this proposed method. A series of validation studies of the present method was performed under the optimal conditions. Good linearities were obtained with the correlation coefficients in the range of 0.994-0.999, the detection limits were ranged from 13 to 40 ng/mL. Sensitivity enhancement factors (SEFs) were in the range of 28.5-46.8 compared with traditional injection (injection time 3 s). Therefore, the proposed method was successfully applied for the separation and concentration of neutral analytes in real samples.

2.
Food Chem ; 303: 125394, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31473455

RESUMO

A simple and effective vesicle based ultrasonic-assisted extraction (UAE) method was developed for extraction of active compounds in functional food. The target analytes were determined by ultra-high performance liquid chromatography with ultraviolet detector. Surfactant vesicle was adopted as extraction solvent. Different operating conditions including the type and concentration of vesicle, extraction time and solid to liquid ratio were investigated by single-factor experiments and response surface methodology. Optimized experimental conditions were 1% (w/v) of DTAB/SDS vesicle, 20 min of extraction time and 160 mg/mL of solid to liquid ratio. The proposed method provided good linearity in the linear range of 10-1000 µg/mL with regression coefficients larger than 0.999, low limits of detection of 27.64-55.67 ng/mL, good precision with relative standard deviations below 0.35%, and satisfactory recoveries of 83.84-90.92% for tested saponins. Consequently, the proposed vesicle based UAE method was well suited for the extraction of saponins in Panax notoginseng.


Assuntos
Fracionamento Químico/métodos , Panax notoginseng/química , Saponinas/isolamento & purificação , Ultrassom , Cromatografia Líquida de Alta Pressão , Saponinas/análise
3.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 50(3): 357-361, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31631603

RESUMO

Objectives: To assess morphological changes of distal aorta and the risk factors for adverse aortic remodeling inpost-TEVAR(thoracic endovascular aortic repair) patients with acute Stanford B aortic dissection. Methods: We retrospectively investigated the patients who underwent TEVAR for a type B dissection between October 2005 and December 2015. CT angiogram (CTA) was obtained for each patients preoperatively, postoperatively and during the post-operational follow-up. Based on Criadol partition principle, we divided the aorta into descending thoracic aorta area, suprarenal abdominal aorta area, infrarenal abdominal aorta area and iliac artery area, and evaluated the distribution of aortic tears and the form of true and false lumen in different aortic partition. Univariate and multivariate logistic regression analyses were used to analyze the risk factors affecting distal aortic remodeling. Results: Of 216 patients (mean follow-up (3.9±2.1) years) who were regularly followed up in our center, 47 patients (21.8%) occurred adverse remodeling in distal aorta. Univariate logistic regression indicated that abnormal aortic wall structure (Marfan's syndrome) and patent false lumen (existence of distal tears, decreased complete false lumen thrombosis) were associated with distal aortic adverse remodeling. Multivariate logistic regression showed that more tears in descending thoracic aorta area ( OR=1.36, 95% CI=1.12-1.58, P=0.005) and less tears in infrarenal abdominal aorta area ( OR=0.49, 95% CI=0.22-0.71, P<0.001) were independent risk factors affecting remodeling in distal aorta after TEVAR. Conclusions: Aortic wall structure abnormalities, a patent false lumen, more tears in descending thoracic aorta area, less tears in infrarenal abdominal aorta area are independent risk factors for adverse aortic remodeling in post-TEVAR patients with acute Stanford B aortic dissection.


Assuntos
Aneurisma Dissecante/patologia , Aneurisma da Aorta Torácica/patologia , Procedimentos Endovasculares , Remodelação Vascular , Aneurisma Dissecante/cirurgia , Aneurisma da Aorta Torácica/cirurgia , Humanos , Estudos Retrospectivos , Fatores de Risco , Resultado do Tratamento
4.
Phytochem Anal ; 30(6): 710-719, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31264752

RESUMO

INTRODUCTION: The main active components in hawthorn leaves possess various biological activities such as anti-inflammatory, antioxidant, and hypolipidemic effects. Therefore, it is necessary to develop an effective and reliable extraction method to extract these active compounds from hawthorn leaves. OBJECTIVE: To establish a simple, rapid, and sensitive method for extraction and determination of polyphenolic compounds from hawthorn leaves. METHODS: In this study, a microwave-assisted reaction and extraction (MARE) combined with ultra-high-performance liquid chromatography with ultraviolet detector method was established to extract and determine the polyphenolic compounds in hawthorn leaves. The solid reagent aqueous solutions were applied as extraction solvents, preventing the use of organic solvents. The target analytes were identified by quadrupole time-of-flight tandem mass spectrometry. Several experimental parameters that can significantly affect the extraction efficiency were evaluated and optimised. RESULTS: The optimal conditions were as follows: 0.1 g of sodium carbonate was used as solid reagent, the amount of sodium borate was set at 0.01 g, extraction time was 10 min, extraction temperature was set at 50°C, pH value was adjusted to 7. The validation experiments demonstrated that the method had high sensitivity with the limits of detection in the range 26.5-37.7 ng/mL. The average recoveries ranged from 80.22% to 93.27%. CONCLUSION: In this work, the proposed MARE method was successfully applied to extract and determine polyphenolic compounds in hawthorn leaf samples. Compared with other reported methods, the present method was faster, greener, and more sensitive.


Assuntos
Crataegus/química , Micro-Ondas , Folhas de Planta/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Polifenóis/análise , Reprodutibilidade dos Testes
5.
Electrophoresis ; 39(17): 2218-2227, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29869395

RESUMO

A rapid, simple, and efficient sample extraction method based on micro-matrix-solid-phase dispersion (micro-MSPD) was applied to the extraction of polyphenols from pomegranate peel. Five target analytes were determined by ultra-HPLC coupled with Q-TOF/MS. Carbon molecular sieve (CMS) was firstly used as dispersant to improve extraction efficiency in micro-MSPD. The major micro-MSPD parameters, such as type of dispersant, amount of dispersant, grinding time, and the type and the volume of elution solvents, were studied and optimized. Under optimized conditions, 26 mg of pomegranate peel was dispersed with 32.5 mg of CMS, the grinding time was selected as 90 s, the dispersed sample was eluted with 100 µL of methanol. Results showed that the proposed method was of good linearity for concentrations of analytes against their peak areas (coefficient of determination r2 > 0.990), the LOD was as low as 3.2 ng/mL, and the spiking recoveries were between 88.1 and 106%. Satisfactory results were obtained for the extraction of gallic acid, punicalagin A, punicalagin B, catechin, and ellagic acid from pomegranate peel sample, which demonstrated nice reliability and high sensitivity of this approach.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Lythraceae/química , Espectrometria de Massas/métodos , Polifenóis/isolamento & purificação , Extração em Fase Sólida/métodos , Carbono/química , Limite de Detecção , Modelos Lineares , Extratos Vegetais/química , Polifenóis/análise , Polifenóis/química , Reprodutibilidade dos Testes
6.
Food Chem ; 262: 118-128, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29751898

RESUMO

In this study, dispersive micro solid phase extraction (DMSPE) combined with ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry method was established to extract and determine sudan dyes and their metabolites in real samples. The crown ether microfunctionalized multi-walled carbon nanotubes (MWCNTs) was applied as the sorbent in DMSPE procedure. Several experimental parameters that can effect the extraction performance of the DMSPE method were investigated separately by a univariate method. The validation data showed that the limits of detection were in the range of 0.084-13.13 µg/kg, the mean recoveries were ranged from 80.15 to 103.58% for six samples. Compared with other published methods, the proposed method was more effective, more time-saving and more eco-friendly. Finally, the developed method was successfully applied to enrich and detect sudan dyes and their metabolites in real samples.


Assuntos
Compostos Azo/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Corantes/isolamento & purificação , Análise de Alimentos/métodos , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Compostos Azo/análise , Corantes/análise , Éteres de Coroa/química , Limite de Detecção , Nanotubos de Carbono/química
7.
J Chromatogr A ; 1561: 1-12, 2018 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-29807708

RESUMO

Mycotoxins are a group of secondary fungi metabolites present in foods that cause adverse effects in humans and animals. The objective of this study was to develop and validate a reliable and sensitive method to determine the presence of fumonisin B1, aflatoxin B1, ochratoxin B, T-2 toxin, ochratoxin A and zearalenone. A rapid, effective process, which involves microwave-assisted dispersive micro-solid phase extraction (MA-d-µ-SPE), has been proposed for the extraction and detection of 6 mycotoxins in peach seed, milk powder, corn flour and beer sample matrixes, for subsequent analysis by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS). Several experimental parameters (type of dispersant, concentration of dispersant, vortex time, type of desorption solvent and pH) affecting the extraction efficiency were systematically studied and optimized. The optimum extraction conditions involved immersing 2.5 µg/mL of nano zirconia (as dispersant) in a 5 mL sample solution. After 2 min of extraction by vigorous shaking, the target analytes were desorbed by 100 µL of chloroform at pH 4.5. The results indicated good linearity in the range of 0.0074-3.6 µg/mL (r ≥ 0.9982), low limits of detection (0.0036-0.033 µg/kg for solid samples and 0.0022-0.017 ng/mL for beer), acceptable reproducibility (relative standard deviation (RSD%) 2.08-2.76% for retention time and 3.51-4.59% for peak area, n = 3), and satisfactory spiked recoveries (84.27-104.96%) for studied mycotoxins in sample matrixes, which demonstrated that MA-d-µ-SPE coupled with UHPLC-Q-TOF/MS is a useful tool for analysis of multi-mycotoxin.


Assuntos
Análise de Alimentos/métodos , Nanopartículas Metálicas/química , Micro-Ondas , Micotoxinas/análise , Micotoxinas/isolamento & purificação , Microextração em Fase Sólida/métodos , Zircônio/química , Cerveja/análise , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Limite de Detecção , Espectrometria de Massas em Tandem/métodos
8.
J Chromatogr A ; 1537: 10-20, 2018 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-29336808

RESUMO

A simple and effective method of miniaturized solid-phase extraction (mini-SPE) was developed for the simultaneous purification and enrichment of macrolide antibiotics (MACs) (i.e. azithromycin, clarithromycin, erythromycin, lincomycin and roxithromycin) from honey and skim milk. Mesoporous MCM-41 silica was synthesized and used as sorbent in mini-SPE. Several key parameters affecting the performance of mini-SPE procedure were thoroughly investigated, including sorbent materials, amount of sorbent and elution solvents. Under the optimized condition, satisfactory linearity (r2 > 0.99), acceptable precision (RSDs, 0.3-7.1%), high sensitivity (limit of detection in the range of 0.01-0.76 µg/kg), and good recoveries (83.21-105.34%) were obtained. With distinct advantages of simplicity, reliability and minimal sample requirement, the proposed mini-SPE procedure coupled with ultrahigh performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry could become an alternative tool to analyze the residues of MACs in complex food matrixes.


Assuntos
Análise de Alimentos/métodos , Mel/análise , Macrolídeos/isolamento & purificação , Leite/química , Dióxido de Silício/química , Extração em Fase Sólida/métodos , Animais , Antibacterianos/análise , Antibacterianos/isolamento & purificação , Bovinos , Cromatografia Líquida de Alta Pressão , Limite de Detecção , Macrolídeos/análise , Reprodutibilidade dos Testes , Solventes/análise , Espectrometria de Massas em Tandem
9.
Food Chem ; 239: 1075-1084, 2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-28873524

RESUMO

A simple, green and effective extraction method, namely, pyridinium ionic liquid- (IL) based liquid-solid extraction (LSE), was first designed to extract the main inorganic and organic iodine compounds (I-, monoiodo-tyrosine (MIT) and diiodo-tyrosine (DIT)). The optimal extraction conditions were as follows: ultrasonic intensity 100W, IL ([EPy]Br) concentration 200mM, extraction time 30min, liquid/solid ratio 10mL/g, and pH value 6.5. The morphologies of Laminaria were studied by scanning electron microscopy and transmission electron microscopy. The recovery values of I-, MIT and DIT from Laminaria were in the range of 88% to 94%, and limits of detection were in the range of 59.40 to 283.6ng/g. The proposed method was applied to the extraction and determination of iodine compounds in three Laminaria. The results showed that IL-based LSE could be a promising method for rapid extraction of bioactive iodine from complex food matrices.


Assuntos
Iodo/isolamento & purificação , Laminaria , Cromatografia Líquida de Alta Pressão , Líquidos Iônicos , Extração Líquido-Líquido
10.
Sci Rep ; 7(1): 7496, 2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28790408

RESUMO

A simple, rapid and eco-friendly approach based on matrix solid-phase dispersion microextraction (MSPDM) followed by ultrahigh performance liquid chromatography coupled with electrochemical detection (UHPLC-ECD) was presented for the microextraction and determination of six phenolic acids in a plant preparation (Danshen tablets). The parameters that influenced the extraction performance of phenolic acids were investigated and optimized. The optimal MSPDM conditions were determined as follows: sorbent, using graphene nanoplatelets with sample/sorbent ratio of 1:1, grinding time set at 60 s, and 0.2 mL of water as elution solvent. Under the optimum conditions, the validation experiments indicated that the proposed method exhibited good linearity (r2 ≥ 0.9991), excellent precision (RSD ≤ 4.57%), and satisfactory recoveries (82.34-98.34%). The limits of detection were from 1.19 to 4.62 ng/mL for six phenolic acids. Compared with other reported methods, this proposal required less sample, solvent and extraction time. Consequently, the proposed method was successfully used to the extraction and determination of phenolic acids in Danshen tablets.

11.
J Chromatogr A ; 1515: 37-44, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28789800

RESUMO

Two kinds of extraction methods ultrasonic-assisted micellar extraction (UAME) and microwave-assisted micellar extraction (MAME) coupled with ultra-high performance liquid chromatography with ultraviolet detector (UHPLC-UV) were developed and evaluated for extraction and determination of zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol in Rhizoma Zingiberis and Rhizoma Zingiberis Preparata. A biosurfactant, hyodeoxycholic acid sodium salt, was used in micellar extraction. Several experimental parameters were studied separately by a univariate method. The result indicated that the MAME was more efficient than UAME. The optimal conditions of MAME were as follows: 100mM of hyodeoxycholic acid sodium salt was used as surfactant, the irradiation time was set at 10s and the extraction temperature was set at 60°C. The validation results indicated that the limits of detection were in the range of 3.80-8.11ng/mL. The average recoveries were in the range of 87.32-103.12% for the two samples at two spiking levels. Compared with other reported methods, the proposed MAME-UHPLC-UV method was more effective, quicker (10s) and more eco-friendly.


Assuntos
Catecóis/isolamento & purificação , Técnicas de Química Analítica/métodos , Cromatografia Líquida de Alta Pressão , Álcoois Graxos/isolamento & purificação , Gengibre/química , Limite de Detecção , Micelas , Micro-Ondas , Rizoma/química , Tensoativos/química , Temperatura Ambiente , Ultrassom
12.
J Chromatogr A ; 1509: 50-59, 2017 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-28645755

RESUMO

Zwitterionic surfactant, used as extractant in microwave-assisted extraction (MAE) was investigated for the first time to extract organic and inorganic iodines from kelp samples. Optimized conditions for the MAE were 200W of microwave irradiation power, 100°C of extraction temperature, 10min of microwave irradiation time, 1g of sample, and 20mL of solvent volume. Ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) was used for the quantitative and qualitative analyses of the iodines. Under the optimum experimental conditions, KI, MIT and DIT were identified in kelp samples, the limits of detection of these analytes were ranged between 3.39 and 6.31ng/mL. The recoveries for spiked samples obtained from different areas were all higher than 92.48%. Compared with the ultrasound-assisted extraction, the proposed method is faster and more effective. Thus, the combination of zwitterionic surfactant-MAE and UHPLC-Q-TOF/MS made up a simple, rapid and effective approach for extraction and determination of iodine compounds in complex seaweed materials.


Assuntos
Fracionamento Químico/métodos , Iodo/isolamento & purificação , Extratos Vegetais/isolamento & purificação , Alga Marinha/química , Tensoativos/química , Verduras/química , Fracionamento Químico/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Iodo/química , Espectrometria de Massas/métodos , Micelas , Micro-Ondas , Extratos Vegetais/química
13.
J Chromatogr A ; 1499: 132-139, 2017 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-28390669

RESUMO

An environmentally friendly ionic liquid-in-water (IL/W) microemulsion was established and applied as mobile phase in microemulsion liquid chromatography (MELC) with ultraviolet (UV) detection or electrochemical detector (ECD) for analysis of phenolic compounds in real samples. The optimal condition of the method was using the best composition of microemulsion (0.2% w/v [HMIM]PF6, 1.0% w/v SDS, 3.0% w/v n-butanol, 95.8% v/v water, pH 2.5) with UV detection. The validation results indicated that the method provided high degree of sensitivity, precision and accuracy with the low limit of detections ranged from 17.9-238ng/mL, satisfactory mean recovery values in the range of 80.1-105% and good linearity (r2>0.9994). Additionally, this method exhibited high selectivity and resolution for the analytes and was more eco-friendly compared with traditional MELC method. Consequently, the established IL/W MELC method was successfully applied to simultaneously separate and determine target compounds in Danshen sample and its preparation.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Medicamentos de Ervas Chinesas/análise , Hidroxibenzoatos/análise , Líquidos Iônicos/química , Salvia miltiorrhiza/química , Cromatografia Líquida de Alta Pressão/instrumentação , Eletroquímica/instrumentação , Eletroquímica/métodos , Emulsões/química , Fenantrolinas/análise , Espectrofotometria Ultravioleta/instrumentação , Espectrofotometria Ultravioleta/métodos , Água/química
14.
Anal Chim Acta ; 963: 24-32, 2017 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-28335972

RESUMO

An ionic liquid-(IL) based micellar extraction combined with microcrystalline cellulose- (MCC) assisted dispersive micro solid-phase extraction method was developed to extract phenolic compounds from propolis. A total of 20 target compounds were identified by ultra-high- performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. The main extraction parameters were optimized and included the ultrasonic power, ultrasonic time, sample pH, type of IL, the concentration of [C12mim]Br, extraction time, concentration of MCC, type of sorbent and type of elution solvents. Under the optimum conditions, the proposed method exhibited good linearities (r2 ≥ 0.999) for all plant phenolic compounds with the lower limits of detection in the range of 0.21-0.41 ng/mL. The recoveries ranged from 82.74% to 97.88% for pinocembrin, chrysin and galangin. Compared with conventional solvent extraction, the present method was simpler and more efficient and required less organic solvent and a shorter extraction time. Finally, the methodology was successfully used for the extraction and enrichment of phenolic compounds in propolis.


Assuntos
Celulose/química , Líquidos Iônicos/química , Microextração em Fase Líquida/métodos , Micelas , Fenóis/isolamento & purificação , Própole/química , Ondas Ultrassônicas , Adsorção , Fenóis/química
15.
Food Chem ; 226: 141-148, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28254005

RESUMO

A cyclodextrin-based miniaturized solid-phase extraction was developed to extract biopesticides from water and vegetable juices. The analytes were detected by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. In the solid-phase extraction (SPE) procedure, the liquid sample solution is passed through a packed column filled with 40mg of HP-ß-CD, and then the target analytes are absorbed and finally eluted with methanol-acetic acid (90:10, v/v) into a collection tube. The limits of quantification ranged from 3.73 to 16.51ng/mL for a water matrix, from 2.62 to 13.23ng/mL for an orange juice matrix and from 1.76 to 10.35ng/mL for a tomato juice matrix, respectively. The average recovery values were in the range of 88.3-95.9% for the spiked samples. The established methodology was successfully applied to analyze sanguinarine, berberine, rotenone and osthole in water, orange juice and tomato juice.


Assuntos
Agentes de Controle Biológico/química , Cromatografia Líquida de Alta Pressão/métodos , Ciclodextrinas/metabolismo , Sucos de Frutas e Vegetais/microbiologia , Espectrometria de Massas/métodos , Extração em Fase Sólida/métodos , Microbiologia da Água , Agentes de Controle Biológico/análise
16.
J Chromatogr A ; 1477: 1-10, 2016 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-27908494

RESUMO

This study presents an effective method of using miniaturized matrix solid phase dispersion (MSPD) for the microextraction of inorganic iodine and iodinated amino acids from seaweed samples. Quantification of the target analytes was performed by ultrahigh performance liquid chromatography with UV detection. Molecular sieve (SBA-15) was chosen as the dispersing adsorbent with an ionic liquid (1-dodecyl-3-methylimidazolium bromide) as the elution solvent. The experimental conditions for the MSPD, such as the type of sorbent, ratio of sorbent to sample, type and concentration of the elution solvent, and grinding time were evaluated and optimized. Under the final working conditions, good recoveries were obtained in the range of 86.5-95.4%, with relative standard deviation values below 6.0% in all cases. The limits of detection and limits of quantitation were in the ranges of 3.7-16.7ng/mL and 12.4ng/mL, respectively. Compared with common ultrasound assisted extraction, the advantages of this green approach are low consumption of the sorbent and solvent, short extraction time and good selectivity, even in complicated matrices. The proposed SBA-15-based MSPD method was successfully applied to the microextraction of potassium iodide, 3-iodo-l-tyrosine, and 3,5-diiodo-l-tyrosine from kelp, nori and undaria pinnatifida, respectively.


Assuntos
Aminoácidos/isolamento & purificação , Iodo/isolamento & purificação , Líquidos Iônicos/química , Extração em Fase Sólida/métodos , Adsorção , Calibragem , Cromatografia Líquida de Alta Pressão , Imidazóis/química , Limite de Detecção , Porosidade , Reprodutibilidade dos Testes , Alga Marinha/química , Alga Marinha/ultraestrutura , Dióxido de Silício/química , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo
17.
J Chromatogr A ; 1472: 16-26, 2016 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-27776775

RESUMO

An analytical procedure based on matrix solid phase dispersion (MSPD) microextration and ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was developed for the determination of isomeric triterpenoid acids (maslinic acid, corosolic acid, oleanolic acid and ursolic acid) in loquat leaves. Microcrystalline cellulose was used for the first time as a solid sorbent in MSPD microextration. Compared with the traditional extraction methods, the proposed method possessed the advantages of shorter extraction time, and lower consumption of sample, sorbent and organic solvent. The MSPD parameters that influenced the extraction efficiency of isomeric analytes were investigated and optimized in detail. Under the optimized conditions, good linearity was obtained with correlation coefficients higher than 0.9990. The limits of detection and quantification were 19.6-51.6µg/kg and 65.3-171.8µg/kg, respectively. Meanwhile, the recoveries obtained for all the analytes were ranging from 90.1% to 107.5%. Finally, the optimized method was successfully applied for analyzing these isomeric acids in loquat leaves samples obtained from different cultivated areas.


Assuntos
Celulose/química , Eriobotrya/química , Ácido Oleanólico/isolamento & purificação , Folhas de Planta/química , Extração em Fase Sólida/métodos , Triterpenos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Isomerismo , Limite de Detecção , Ácido Oleanólico/química , Solventes/química , Espectrometria de Massas em Tandem , Triterpenos/química
18.
Electrophoresis ; 37(23-24): 3118-3125, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27699822

RESUMO

A simple, efficient, and green chitosan-assisted liquid-solid extraction method was developed for the sample preparation of isoquinoline derivative alkaloids followed by microemulsion LC. The optimized mobile phase consisted of 0.8% w/v of ethyl acetate, 1.0% w/v of SDS, 8.0% w/v of n-butanol, 0.1% v/v acetic acid, and 10% v/v ACN. Compared to pharmacopoeia method and organic solvent extraction, this new approach avoided the use of volatile organic solvents, replacing them with relatively small amounts of chitosan. Under the optimum conditions, good linearity (r2 > 0.9980) for all calibration curves and low detection limits between 0.05 and 0.10 µg/mL were achieved. The presented procedure was successfully applied to determine alkaloids in Rhizoma coptidis with satisfactory recoveries (81.3-106.4%).


Assuntos
Alcaloides/análise , Quitosana/química , Cromatografia Líquida/métodos , Isoquinolinas/análise , Microextração em Fase Líquida/métodos , Alcaloides/isolamento & purificação , Medicamentos de Ervas Chinesas/química , Isoquinolinas/isolamento & purificação , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes
19.
J Chromatogr A ; 1468: 86-94, 2016 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-27646060

RESUMO

Thrombin was immobilized on dynabeads®M-270 epoxy by direct covalent binding method for the first time. The enzyme coated magnetic beads were combined with ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry technique to establish a simple, rapid and reliable approach for screening thrombin inhibitors from Danshen preparation. The conjugation of thrombin to the magnetic beads was characterized using scanning electron microscope, transmission electron microscope and infrared spectroscopy, and the enzyme activity was determined by the analysis of enzyme-bead ratio and peak areas of target compounds. Several factors including amount of magnetic beads, type of elution solvent, incubation temperature and time were optimized. Additionally, two thrombin-bound compounds (protocatechuic aldehyde and salvianolic acid C) in Danshen injection were validated by conventional inhibitory assay and the IC50 values were 286.11 and 66.09µg/mL, respectively. Our findings suggested that the proposed method was efficient in screening active compounds from medicinal plants.


Assuntos
Antitrombinas/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Medicamentos de Ervas Chinesas/química , Hidroxibenzoatos/química , Espectrometria de Massas em Tandem , Trombina/antagonistas & inibidores , Antitrombinas/química , Solventes/química
20.
J Chromatogr A ; 1463: 32-41, 2016 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-27515553

RESUMO

A green and economical method for the extraction and preconcentration of natural pigments (curcumin, demethoxycurcumin and bisdemethoxycurcumin) was developed using ultrasound-assisted extraction combined with dispersive micro solid-phase extraction. In this work, Ionic liquids (ILs) were used for the pre-extraction of natural pigments. The pure chitosan nanoparticles (CS NPs) were then used as a sorbent for the microextraction mode. The method involves the use of ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Operating parameters influencing the performance of extraction steps such as type and concentration of ILs, concentration of CS NPs, type of elution solvent, agitation time and pH of sample-extracting solution were investigated. Under the optimum conditions, the proposed method exhibited a low detection limit in the range of 0.11-0.36ng/mL at S/N=3, and good linearities with coefficients of determination (R(2)) higher than 0.9990. The recoveries of turmeric samples were ranging from 90.45% to 105.04% for the three studied curcuminoids with SD of 3.27-6.58. The experimental results indicated that the ILs and CS NPs were the promising materials for the extraction and enrichment of target curcuminoids from complex solid samples.


Assuntos
Quitosana/química , Líquidos Iônicos/química , Nanopartículas/química , Pigmentos Biológicos/isolamento & purificação , Extração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão , Curcuma/química , Limite de Detecção , Rheum/química , Soluções , Solventes/química , Espectrometria de Massas em Tandem , Ultrassom , Raios Ultravioleta
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