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1.
Food Chem ; 308: 125647, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31648088

RESUMO

An analyser was constructed on the basis of on-line connection of capillary electrophoresis over a short separation path with continuous mini-dialysis sample collection. The developed instrument was employed for simultaneous determination of the majority minerals K+, Ca2+, Na+ and Mg2+ (and possibly NH4+ ions) in commercially available unflavoured yoghurts. The cations are released from the organic structures by digestion with boiling 6 mol/L HCl. They were separated from residues of the organic matrix by a dialysis probe and were transferred to a stream of water. From the continuous stream, the dialysate was injected into the separation capillary through a flow-gating interface. Within the reliability interval, the determined total mineral content was equal to their contents stated on the yoghurt labels and the content determined by flame atomic absorption spectrometry and complexometric titration. The relative standard deviation of the electrophoretic determination is mostly about 5%.


Assuntos
Iogurte/análise , Cátions/química , Diálise , Eletroforese Capilar/métodos , Reprodutibilidade dos Testes , Espectrofotometria Atômica , Fatores de Tempo , Água/análise
2.
J Sci Food Agric ; 100(2): 811-816, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31617212

RESUMO

BACKGROUND: Natamycin is often added to pastries, cheeses, and beverages. The residual amount of natamycin should be less than 10 mg kg-1 . The current method for its determination in various foodstuffs is high-performance liquid chromatography (HPLC). Capillary electrophoresis (CE) is a simple, fast, and environmentally friendly method with low reagent consumption and comparable separation performance. However, no reports were found on the determination of natamycin in foods by CE. A CE method to determine natamycin is therefore sought. RESULTS: Natamycin in foods was determined by the capillary zone electrophoresis (CZE) method with ultraviolet-visible (UV) detection. Separation conditions were optimized as 20 mM Na2 HPO4 , pH 9.2, with 25 kV applied voltage, and UV detection at 306 nm. Under optimal conditions, electrophoretic analysis was completed in less than 4 min, with a limit of detection (LOD) of 0.065 µg mL-1 and limit of quantitation (LOQ) of 0.22 µg mL-1 . A good linear relationship (r2 = 0.999) was obtained at the range of 0.1-25 µg mL-1 . A comparison with the HPLC-UV method was also carried out according to the National Standards of the People's Republic of China. CONCLUSION: The results obtained by the CZE and HPLC methods are comparable but the proposed CZE method can help us obtain a shorter detection time at low cost. © 2019 Society of Chemical Industry.


Assuntos
Bebidas/análise , Queijo/análise , Cromatografia Líquida de Alta Pressão/métodos , Eletroforese Capilar/métodos , Conservantes de Alimentos/análise , Natamicina/análise , China , Limite de Detecção
3.
Artigo em Inglês | MEDLINE | ID: mdl-31756622

RESUMO

Alkaloids of Sophora flavescens (ASF) has various pharmacological effects, and it is widely used in clinical practice. The aim of this research was to develop an environmentally friendly methodology that enables not only identification but also the quality consistency assessment of Alkaloids of Sophora flavescens. A background electrolyte composed of 50 mmol/L sodium tetraborate solution, 500 mmol/L boric acid and 1.2 mmol/L citric acid was used to conduct the fingerprint analysis coupled with quantitative determination of three components. Linear quantitative profiling method was used for comprehensive quality discrimination of the test samples from both qualitative and quantitative perspectives, and the 27 batches of samples were well differentiated. In addition, the fingerprint-efficacy relationship between chemical components and antioxidant activity in vitro was established using partial least squares regression model, which provided important medicinal efficacy information for quality control.


Assuntos
Alcaloides/análise , Antioxidantes/análise , Eletroforese Capilar/métodos , Sophora/química , Alcaloides/química , Antioxidantes/química , Análise dos Mínimos Quadrados , Limite de Detecção , Extratos Vegetais/química , Análise de Componente Principal , Reprodutibilidade dos Testes
4.
Anal Bioanal Chem ; 411(27): 7261-7272, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31494688

RESUMO

In the recent decade, metal pyrithione complexes have become important biocides for antifouling purposes in shipping. The analysis of metal pyrithione complexes and their degradation products/species in environmental samples is challenging because they exhibit fast UV degradation, transmetalation, and ligand substitution and are known to be prone to spontaneous species transformation within a chromatographic system. The environmental properties of the pyrithione species, e.g., toxicity to target and non-target organisms, are differing strongly, and it is therefore inevitable to identify as well as quantify all species separately. To cope with the separation of metal pyrithione species with minimum species transformation during analysis, a capillary electrophoresis (CE)-based method was developed. The hyphenation of CE with selective electrospray ionization- and inductively coupled plasma-mass spectrometry (ESI-, ICP-MS) provided complementary molecular and elemental information for the identification and quantification of pyrithione species. To study speciation of pyrithiones, a leaching experiment of several commercial antifouling paints containing zinc pyrithione in ultrapure and river water was conducted. Only the two species pyrithione (HPT) and dipyrithione ((PT)2) were found in the leaching media, in concentrations between 0.086 and 2.4 µM (HPT) and between 0.062 and 0.59 µM ((PT)2), depending on the paint and leaching medium. The limits of detection were 20 nM (HPT) and 10 nM ((PT)2). The results show that complementary CE-MS is a suitable tool for mechanistical studies concerning species transformation (e.g., degradation) and the identification of target species of metal pyrithione complexes in real surface water matrices, laying the ground for future environmental studies. Graphical abstract Hyphenation of CE with ESI- and ICP-MS provided complementary molecular and elemental information. Metal pyrithione species released from commercial antifouling paints could be identified and quantified in ultrapure and river water matrices.


Assuntos
Eletroforese Capilar/métodos , Espectrometria de Massas/métodos , Piridinas/análise , Tionas/análise , Limite de Detecção , Pintura , Padrões de Referência , Poluentes Químicos da Água/análise
5.
J Pharm Biomed Anal ; 175: 112769, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31398628

RESUMO

A sensitive detection electrode based on the composite of carbon nanotubes (CNTs) and polylactic acid (PLA) was fabricated for measuring the bioactive constituents in Belamcandae Rhizoma by capillary electrophoresis (CE). The composite was facilely fabricated by packing a blend of CNTs and melted PLA into a fused silica capillary under heat. The prepared CNT-PLA composite was characterized by scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and cyclic voltammetry. The results indicated that PLA bound electrically conductive CNTs to form a well-dispersed composite network for electrochemical sensing. The electrode was employed to the off-line detection of tectoridin and irigenin in Belamcandae Rhizoma to demonstrate its performance in capillary electrophoresis. At a separation voltage of 12 kV, the two isoflavones were well separated and detected within 8 min in a 40-cm fused silica capillary in a borate buffer at pH 9.8. The detection limits for tectoridin and irigenin were measured to be 0.24 and 0.21 µM, respectively.


Assuntos
Medicamentos de Ervas Chinesas/química , Isoflavonas/química , Nanotubos de Carbono/química , Poliésteres/química , Rizoma/química , Eletrodos , Eletroforese Capilar/métodos , Limite de Detecção , Microscopia Eletrônica de Varredura/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
6.
Anal Chim Acta ; 1080: 146-152, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31409464

RESUMO

Field-amplified stacking (FAS) is a commonly used method for enhancing the sensitivity of charged species from low conductive media in capillary electrophoresis. FAS also showed significant sensitivity enhancement effect on a uniform paper fluidic channel by proper design of the electrolyte. In this paper, a novel method of introducing electric field gradient is proposed by geometry design of a 2D paper fluidic channel, and field amplification effect was successfully demonstrated with reduced requirement on the sample's conductivity. Sensitive colorimetric detection of microalbuminuria (MAU) from urine samples was demonstrated by mobile phone camera. Experimental results showed that, with active electric field motivation, up to 93.5% of the loaded protein probe could be effectively transferred and stacked into a narrow band on the newly designed paper fluidic channel. A limit of detection (LOD) of 6.5 mg‧L-1 HSA was achieved with a dynamic range of 10-300 mg‧L-1 (linear in the range of 10-100 mg‧L-1, R2 = 0.991). Combined with selective staining of albumin with bromophenol blue (BPB), the established method was applied to the detection of MAU from clinical urine samples, and consistent results with that of the clinical method were obtained. With this paper-based analytical device (PAD), MAU from highly conductive urine samples can be directly loaded and detected without any pretreatment. This method provides a way to develop highly sensitive point-of-care test (POCT) for rapid screening of some diseases.


Assuntos
Albuminúria/diagnóstico , Colorimetria/métodos , Eletroforese Capilar/métodos , Papel , Albumina Sérica Humana/urina , Azul de Bromofenol/química , Colorimetria/instrumentação , Corantes/química , Eletroforese Capilar/instrumentação , Humanos , Limite de Detecção
7.
Talanta ; 205: 120108, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31450387

RESUMO

In this study, a capillary electrophoresis-tandem mass spectrometry method combining efficient separation and sensitive detection has been developed and validated, for the first time, to quantify acetaminophen and five of its metabolites in urine samples. Optimization of the method has led us to perform detection in positive ESI mode using MeOH-ammonium hydroxide (0.1%) (50:50, v/v) as sheath liquid. Moreover, optimal separation has been obtained in less than 9 min after anodic injection, using an ammonium acetate solution (40 mM, pH 10) as BGE. It was shown that the dilution solvent and the dilution factor to use for sample preparation are critical parameters to avoid peak splitting, to gain in sensitivity and then to obtain an effective analysis method. While a 200-fold factor dilution was shown to be suitable for quantitation of acetaminophen, acetaminophen mercapturate, acetaminophen sulfate and acetaminophen glucuronide, a 20-fold dilution was finally selected for methoxy-acetaminophen and 3-methylthioacetaminophen analysis, thus requiring two successive analyses to be carried out in order to quantify all metabolites. Hyphenation of CE with MS/MS versus UV permits to improve LOQ (10-20-fold factor with respect to previous works for acetaminophen, acetaminophen sulfate and acetaminophen glucuronide). Moreover, use of CE versus HPLC, permits to quantify two additional metabolites, i.e. 3-methylthio-acetaminophen and methoxy-acetaminophen. The method has been validated using the accuracy profile approach with a total error (accuracy) included in the ± 20% range. Thereby, the method allows the quantitation of acetaminophen and acetaminophen mercapturate in the range (0.1-1 mg mL-1), and of acetaminophen sulfate, methoxy-acetaminophen, acetaminophen glutathione and 3-methylthio-acetaminophen in the ranges (0.5-5 mg mL-1), (0.025-0.4 mg mL-1), (9.22-30 mg mL-1) and (0.073-0.4 mg mL-1), respectively. The method was finally applied to the analysis of urine samples of eighteen patients belonging to three different inclusion groups of the ongoing clinical trial, demonstrating that the method is suitable to highlight different metabolic profiles. This work will be subsequently extended to the analysis two hundred and seventy urine samples from patients included in a clinical trial dedicated to the study of acetaminophen metabolism changes after hepatic resection.


Assuntos
Acetaminofen/análogos & derivados , Acetaminofen/urina , Acetaminofen/metabolismo , Eletroforese Capilar/métodos , Humanos , Espectrometria de Massas em Tandem/métodos
8.
Anal Chim Acta ; 1079: 230-236, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387716

RESUMO

The use of immobilized pH gradient (IPG) capillary isoelectric focusing (CIEF) was confirmed to be possible with packed capillaries. The success of this experiment was due to two key factors: first, the use of surface-confined atom transfer radical polymerization method led to an increase in active reaction sites on the surface of silica particles; second, the subsequent free radical reaction caused carrier ampholytes (CAs) to bond faster and firmer. Based on this scheme, both CIEF with free pH gradient and CIEF with IPG were performed in capillaries packed with 3 µm modified silica particles. In our online CIEF-UV platform, both reversible and irreversible adsorption of proteins was shown to be negligible. Four proteins were focused: cytochrome c (pI 10.2), myoglobin (pI 7.3), carbonic anhydrase (pI 5.9) and trypsin inhibitor (pI 4.5). The comparison of the two CIEF columns showed that the time required for focusing in the packed capillary with IPG is only increased by a factor of 1.5 compared to the packed capillary, giving complete focusing in less than 12 min at 400 V/cm. With the increment of the electric field (the maximum at 600 V/cm), the run time was continually decreasing in these packed capillaries while the peak shape was improving. The four proteins (pH 4.5-10.2) could be successfully separated in our online CIEF platform. Moreover, for the newly online CIEF platform, pressure-driven mobilization without an applied electric field was achieved in the packed capillary with immobilized pH gradient.


Assuntos
Eletroforese Capilar/instrumentação , Focalização Isoelétrica/instrumentação , Dióxido de Silício/química , Proteínas Sanguíneas/análise , Eletroforese Capilar/métodos , Humanos , Concentração de Íons de Hidrogênio , Focalização Isoelétrica/métodos
9.
J Chromatogr A ; 1607: 460375, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31353071

RESUMO

Four amino acid chiral ionic liquids were evaluated in dual systems with hydroxypropyl-ß-cyclodextrin to investigate the enantioseparation by CE of a group of seven drugs as model compounds (duloxetine, verapamil, terbutaline, econazole, sulconazole, metoprolol, and nadolol). The use of two of these chiral ionic liquids (tetramethylammonium L-Lysine ([TMA][L-Lys]) and tetramethylammonium L-glutamic acid ([TMA][L-Glu])) as modifiers in CE is reported for the first time in this work whereas tetrabutylammonium L-lysine ([TBA][L-Lys]) and tetrabutylammonium L-glutamic acid ([TBA][L-Glu]) were employed previously in CE although very scarcely. The effect of the nature and the concentration of each ionic liquid added to the separation buffer containing the neutral cyclodextrin on the enantiomeric resolution and the migration time obtained for each drug, was investigated. A synergistic effect was observed when combining each chiral ionic liquid with hydroxypropyl-ß-cyclodextrin in the case of the five compounds for which the cyclodextrin showed enantiomeric discrimination power when used as sole chiral selector (duloxetine, verapamil, terbutaline, econazole, sulconazole). Buffer concentration and pH, temperature and separation voltage were varied in order to optimize the enantiomeric separation of these five compounds using dual systems giving rise to resolutions ranging from 1.1 to 6.6.


Assuntos
2-Hidroxipropil-beta-Ciclodextrina/química , Aminoácidos/química , Eletroforese Capilar/métodos , Líquidos Iônicos/química , Preparações Farmacêuticas/isolamento & purificação , Tampões (Química) , Ácido Glutâmico/química , Concentração de Íons de Hidrogênio , Estereoisomerismo , Temperatura Ambiente
10.
J Chromatogr A ; 1605: 360356, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31327480

RESUMO

A simple and inexpensive approach for determination of various antimicrobial drugs using a purpose-made compact capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C4D) is reported. The objective of the work is to propose an affordable and easily-implemented tool for quality control and detection of counterfeiting of antibiotic formulations in resource constrained developing countries. The design of the purpose-made CE-C4D system was improved according to the feedback from over 10 years of use of our previous instrument. CE-C4D methods were for the first time developed to analyze ß-lactam-based antibiotics commonly used in Vietnam, including single- ß-lactam antibiotics (i.e. Cephalexin, Cefotaxime Sodium, Cefixime and Sulbactam) as well as ß-lactams co-formulated with Sulbactam (i.e. Amoxicillin, Ampicillin, Cefoperazone and Sulbactam). Single ß-lactam antibiotics were analyzed using a background electrolyte (BGE) composed of Tris/Ace (10 mM, pH 7.8) whereas ß-lactam - Sulbactam combinations were simultaneously separated using a BGE containing Tris/Ace (10 mM, pH 7.5). The best achieved detection limits were 2.0 mg/L and 1.0 mg/L for these two groups, respectively. Good agreement between results obtained from CE-C4D and standard confirmation methods (LCMS) was achieved, with a coefficient of determination, r2, of 0.9991. The applicability of the developed CE-C4D method was demonstrated for quality control of 24 ß-lactam-based antimicrobial drugs available in Vietnam.


Assuntos
Antibacterianos/análise , Análise Custo-Benefício , Condutividade Elétrica , Eletroforese Capilar/economia , Eletroforese Capilar/métodos , beta-Lactamas/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Controle de Qualidade
11.
J Agric Food Chem ; 67(31): 8425-8430, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31322874

RESUMO

In recent years, non-targeted methods have been a popular "buzz" phrase in food fraud detection. Using analytical instrumentation techniques, non-targeted methods have been developed and applied in many food and agricultural situations. However, confusion and misstatements remain regarding how the methods are used. This perspective will discuss the definitions related to non-targeted testing, the procedure of developing and validating methods, the techniques and data analysis, and opportunities and challenges regarding the use of this class of analytical methods. The perspective seeks to provide readers with the latest information regarding recent advances in the use of non-targeted methods.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Cromatografia Líquida/métodos , Eletroforese Capilar/métodos , Análise de Alimentos/instrumentação , Humanos , Espectroscopia de Ressonância Magnética/métodos , Espectrometria de Massas/métodos
12.
J Pharm Biomed Anal ; 175: 112763, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31330278

RESUMO

Herbal medicine has been used worldwide as an alternative treatment. Salvia genus is one of the most remarked herbs which is traditionally used in the treatment of many diseases. Therefore, it is a crucial issue to reveal the chemical and biological profiles of different Salvia species. Rosmarinic and carnosic acid are the most well-known bioactive components generally accepted as the main antioxidant compounds in Salvia. This study firstly aims the determination of rosmarinic and carnosic acid contents of 14 Anatolian Salvia species by a simple and rapid capillary electrophoresis method. Moreover, the antioxidant activities and total phenolic contents of the Salvia samples were investigated. α-Glucosidase enzyme inhibitory effects of the samples were tested concerning their antidiabetic activities. The rosmarinic acid contents in the samples were well-correlated with the bioactivities.


Assuntos
Antioxidantes/química , Cinamatos/química , Depsídeos/química , Hipoglicemiantes/química , Salvia/química , Eletroforese Capilar/métodos , Fenóis/química , Extratos Vegetais/química , alfa-Glucosidases/química
13.
J Chromatogr A ; 1605: 360353, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31307792

RESUMO

The aim of this work was to develop a capillary electrophoresis-mass spectrometry (CE-ESI-QToF-MS) method to carry out the metabolic fingerprinting of green and roasted coffee samples (Arabica variety). To evaluate changes in the metabolic profiles of coffee occurring along the roasting process, green coffee beans were submitted to different roasting degrees. The effect of different parameters concerning the electrophoretic separation (background electrolyte, temperature, voltage, and injection time), the MS detection (temperature and flow of drying gas, sheath gas of jet stream temperature, and capillary, fragmentator, nozzle, skimmer, and octapole voltages) and the sheath liquid (composition and flow rate) was studied to achieve an adequate separation and to obtain the largest number of molecular features. The analyses were carried out in positive ESI mode allowing to detect highly polar cationic metabolites present in coffee beans. Non-supervised and supervised multivariate analyses were performed showing a good discrimination among the different coffee groups. Those features having a high variable importance in the projection values on supervised analyses were selected as significant metabolites for their identification. Thus, 13 compounds were proposed as potential markers of the coffee roasting process, being 7 of them tentatively identified and 2 of them unequivocally identified. Different families of compounds such as pyridines, pyrroles, betaines, or indoles could be pointed out as markers of the coffee roasting process.


Assuntos
Café/química , Café/metabolismo , Eletroforese Capilar/métodos , Metabolômica/métodos , Espectrometria de Massas em Tandem/métodos , Coffea/química , Análise Discriminante , Análise dos Mínimos Quadrados , Metaboloma , Análise de Componente Principal
14.
Biomed Chromatogr ; 33(11): e4646, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31291685

RESUMO

A simple, comprehensive and efficient capillary electrophoresis method using a dual cyclodextrin system was developed for the simultaneous determination of seven isoflavones (3'-methoxypuerarin, puerarin, 3'-hydroxypuerarin, ononin, daidzin, daidzein and genistin). Baseline separations of the seven isoflavones were achieved within 11 min with the running buffer consisting of 35 mm sodium tetraborate, 9.0 mm sulfobutylether-ß-cyclodextrin and 30 mm α-cyclodextrin at pH 9.34, and peaks were detected at 254 nm. Other separation parameters included the separation voltage for 15 kV and the working temperature for 25°C. Under the optimum conditions, good linearities were obtained with linear correlation coefficients of seven isoflavones of 0.9978-0.9992. The limits of detection and the limits of quantification were 0.7-2.9 and 2.5-9.5 µg/mL, respectively. Excellent precision and accuracy were obtained. The intraday and interday precision ranged from 0.7 to 2.0% and from 0.8 to 1.9%, respectively. The recoveries of seven analytes were from 97.7 to 103.1%. This method was successfully applied to determine the seven analytes in Radix Puerariae and its preparations.


Assuntos
Medicamentos de Ervas Chinesas/química , Eletroforese Capilar/métodos , Isoflavonas/análise , Isoflavonas/isolamento & purificação , Ciclodextrinas/química , Isoflavonas/química , Limite de Detecção , Modelos Lineares , Pueraria , Reprodutibilidade dos Testes
15.
J Agric Food Chem ; 67(28): 8053-8060, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31276393

RESUMO

The development of analytical methods for acrylamide formed during food processing is of great significance for food safety, but limited by its inherent characteristics, the analysis of acrylamide is a continuing challenge. In this study, an efficient derivatization strategy for acrylamide based on thiol-ene click reaction with cysteine as derivatization reagent was proposed, and the resulting derivative was then analyzed by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D). After systematic investigation including catalyst dosage (0-20 mM), reaction temperature (30-90 °C) and time (1-60 min), and cysteine concentration (0.2-3.6 mM), acrylamide could be efficiently labeled by 2.0 mM cysteine at 70 °C for 10 min using 4 mM n-butylamine as catalyst. Application of 10 mM triethylamine as separation buffer, the labeled acrylamide was analyzed within 2.0 min, and the relative standard deviations of migration time and peak area were less than 0.84% and 5.6%, indicating good precision. The C4D signal of acrylamide derivative showed a good linear relationship with acrylamide concentration in the range of 7-200 µM with the correlation coefficient of 0.9991. The limit of detection and limit of quantification were calculated to be 0.16 µM and 0.52 µM, respectively. Assisted further by the QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample pretreatment, the developed derivatization strategy and subsequent CE-C4D method were successfully applied for the determination of acrylamide in potato products.


Assuntos
Acrilamida/análise , Química Click/métodos , Eletroforese Capilar/métodos , Solanum tuberosum/química , Culinária , Cisteína/química , Temperatura Alta , Limite de Detecção , Tubérculos/química
16.
J Chromatogr A ; 1603: 361-370, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31257038

RESUMO

Separation efficiency is ideally controlled by molecular diffusion in capillary electrophoresis (CE). However, other adverse phenomena, such as solute adsorption on capillary surface, tend to increase the peak dispersion. An interesting alternative to limit the solute adsorption is to avoid as much as possible the contact of the solute with the capillary surface by elaborating superhydrophobic (SH) coatings on fused silica capillary surfaces. This work describes an optimized protocol to get non-wettable SH coating using hydrophobically modified silica nanoparticle suspensions (Glaco™), based on simple capillary flushes and thermal stabilization. In this protocol, the control of the air flushing after the introduction of the Glaco™ suspension in the capillary was found crucial to get optimized coating coverage and reproducibility. The SH coating was characterized by ellipsometry, atomic force microscopy, scanning electron microscopy, contact angle (about 159°) and the observation of the meniscus of water in the coated capillary. The hydrodynamic behavior of the SH coated capillary was investigated by plotting the Poiseuille law. Finally, electrophoretic separations of a peptide mixture in acidic conditions demonstrated the interest of this approach with an increase by a factor 2 of the separation efficiency compared to fused silica capillary.


Assuntos
Eletroforese Capilar/métodos , Interações Hidrofóbicas e Hidrofílicas , Adsorção , Vidro/química , Hidrodinâmica , Microscopia de Força Atômica , Peptídeos/análise , Reprodutibilidade dos Testes
17.
J Chromatogr A ; 1606: 360332, 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31262513

RESUMO

Electromigration techniques have recently emerged as an alternative analytical tool for nanoparticles characterization. Due to the high throughput capability and separation efficiency their application for detection/quantification of nanomaterials in samples of various origin has attracted much attention. While the electromigration techniques are known to suffer from insufficient detection sensitivity, a number of papers investigating on-line preconcentration of nanoparticles in capillary electrophoresis was addressed to the issue. In this work the available literature on nanoparticles stacking in electrodriven separation techniques was reviewed. The discussion was supported by theoretical background. A special emphasis was put on the stability of nanoparticles dispersion during electrophoretic process. The considerations on future perspectives were included in final remarks.


Assuntos
Eletroquímica/métodos , Nanopartículas/química , Sistemas On-Line , Eletrodos , Eletroforese Capilar/métodos , Micelas
18.
Anal Bioanal Chem ; 411(22): 5855-5866, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31286176

RESUMO

Recently, increasing attention has been given to the research on chiral ionic liquids (CILs) in chiral separation field; however, only a few literatures focus on the exploration of CILs as the sole chiral selector. In this study, an ionic liquid chiral selector based on antibiotic, namely tetramethylammonium clindamycin phosphate (TMA-CP), was originally synthesized and subsequently utilized for enantioseparation in capillary electrophoresis (CE). Remarkably improved separations of eight racemic analytes were achieved in TMA-CP system in contrast to the clindamycin phosphate (CP) system. The optimal separation conditions were determinated by systematic experiments on several crucial parameters including the type and proportion of organic modifier, CIL concentration, buffer pH, and applied voltage. Additionally, molecular modeling with AutoDock was applied to probe into the chiral recognition mechanism of the ionic liquid chiral selectors, which well corresponded with the experimental results. It is the first time that antibiotic-based ionic liquid was exploited as favorable sole chiral selector in CE, and this strategy has paved a new way for development of novel ionic liquids chiral selectors based on antibiotics. Graphical abstract.


Assuntos
Antibacterianos/química , Clindamicina/análogos & derivados , Eletroforese Capilar/métodos , Líquidos Iônicos/química , Tampões (Química) , Clindamicina/química , Concentração de Íons de Hidrogênio , Simulação de Acoplamento Molecular , Reprodutibilidade dos Testes , Estereoisomerismo
19.
Clin Biochem ; 71: 69-71, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31299317

RESUMO

We report two cases of hemoglobin Sendagi in a Romanian family residing in Spain: a four-year-old boy and his mother, who had been previously diagnosed with another type of congenital hemolytic anemia and had undergone splenectomy in her country during childhood. The unstable hemoglobin variant, hemoglobin Sendagi, is characterized by decreased oxygen affinity caused by replacement of one of the critical amino acid residues, phenylalanine beta 42 (CD1) of the beta-chain, with valine in the heme pocket, resulting in methemoglobin formation. As a result of migratory movements in Europe, new disease-causing hemoglobin variants are emerging in our country. Here, capillary electrophoresis enabled the identification of the variant and a molecular study was used to establish an accurate diagnosis.


Assuntos
Eletroforese Capilar/métodos , Hemoglobinas Anormais/metabolismo , Mutação , Adulto , Pré-Escolar , Feminino , Humanos , Masculino
20.
Talanta ; 204: 182-188, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357280

RESUMO

We described an aptamer based and Mg2+ mediated free zone capillary electrophoresis-laser induced fluorescence (CE-LIF) assay for aflatoxin B1 (AFB1) detection. This CE-LIF assay applied an anti-AFB1 aptamer with a single fluorescein (FAM) label at 5' end and a short complementary DNA (cDNA). In the absence of AFB1, the cDNA hybridized with the aptamer probe and formed a duplex DNA. The use of running buffer containing MgCl2 allowed good isolation of the duplex DNA from the single stranded DNA in CE. We found introducing a biotin label on the cDNA further improved the isolation. When AFB1 existed in sample solution, the aptamer probe bound with AFB1, dissociating from the duplex DNA. Thus, the duplex DNA peak decreased, while the aptamer probe peak increased during CE-LIF analysis. We achieved detection of AFB1 by measuring the aptamer probe peak. The length of cDNA, the ratio of aptamer to cDNA, and the concentration of MgCl2 in sample buffer and separation buffer had great effect on the aptamer based CE-LIF assay. Under optimized conditions, the detection limit of AFB1 was 0.2 nM, and the dynamic range was from 0.2 nM to 500 nM. Limit of quantitation was 0.5 nM. This CE-LIF assay enabled detection of AFB1 spiked in diluted human serum, diluted human urine, and corn flour samples. This assay exhibits potential for wide application as it integrates the rapidity, high sensitivity, low sample consumption of CE-LIF analysis and the strengths of aptamer.


Assuntos
Aflatoxina B1/sangue , Aflatoxina B1/urina , Eletroforese Capilar/métodos , Contaminação de Alimentos/análise , Magnésio/química , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/genética , Biotina/química , DNA Complementar/química , DNA Complementar/genética , Farinha/microbiologia , Fluoresceínas/química , Fluorescência , Corantes Fluorescentes/química , Humanos , Limite de Detecção , Hibridização de Ácido Nucleico , Zea mays/microbiologia
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