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1.
Anal Bioanal Chem ; 412(17): 4127-4134, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32328692

RESUMEN

In this study, we demonstrated nano-flow injection analysis (nano-FIA) with quadrupole time-of-flight mass spectrometry (Q-TOFMS) for 17 highly polar intermediates produced during glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway (PPP). We optimized the analytical conditions for nano-flow injection/Q-TOFMS, and set the flow rate and ion source temperature to 1000 nL/min and 150 °C, respectively. Under optimal conditions, a single run was finished within 3 min, and the RSD value of 50 sequential injections was 4.2%. The method also showed quantitativity of four stable-isotope-labeled compounds (r2 > 0.99), demonstrating its robustness, high repeatability, and specificity. In addition, we compared three sample-preparation methods for rodent blood samples and found that protein precipitation with threefold methanol was the most effective. Finally, we applied the method to plasma samples from the serotonin syndrome (SS) model and control rats, the results of which were evaluated by principal component analysis (PCA). The two groups showed clearly separated PCA score plots, suggesting that the method could successfully catch the differences in metabolic profiles between SS and control rats. The results obtained from our new method were further validated by using the established gas chromatography/tandem mass spectrometry method, which demonstrated that there were good correlations between the two methods (R = 0.902 and 0.958 for lactic acid and malic acid, respectively, each at p < 0.001), thus proving the validity of our method. The method described here enables high-throughput analysis of metabolites and will be of use for the rapid analysis of metabolic profiles. Graphical abstract.


Asunto(s)
Análisis de Inyección de Flujo/instrumentación , Espectrometría de Masas/instrumentación , Metaboloma , Síndrome de la Serotonina/metabolismo , Animales , Ciclo del Ácido Cítrico , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/métodos , Glucólisis , Masculino , Espectrometría de Masas/economía , Espectrometría de Masas/métodos , Ratones Endogámicos ICR , Vía de Pentosa Fosfato , Análisis de Componente Principal , Ratas , Síndrome de la Serotonina/sangre , Factores de Tiempo
2.
J Am Soc Mass Spectrom ; 30(12): 2580-2583, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31724102

RESUMEN

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a biophysical technique well suited to the characterization of protein dynamics and protein-ligand interactions. In order to accurately define the rate of exchange, HDX experiments require the repeated measure of deuterium incorporation into the target protein across a range of time points. Accordingly, the HDX-MS experiment is well suited to automation, and a number of automated systems for HDX-MS have been developed. The most widely utilized platforms all operate an integrated design, where robotic liquid handling is interfaced directly with a mass spectrometer. With integrated designs, the exchange samples are prepared and injected into the LC-MS following a "real-time" serial workflow. Here we describe a new HDX-MS platform that is comprised of two complementary pieces of automation that disconnect the sample preparation from the LC-MS analysis. For preparation, a plate-based automation system is used to prepare samples in parallel, followed by immediate freezing and storage. A second piece of automation has been constructed to perform the thawing and LC-MS analysis of frozen samples in a serial mode and has been optimized to maximize the duty cycle of the mass spectrometer. The decoupled configuration described here reduces experiment time, significantly improves capacity, and improves the flexibility of the platform when compared with a fully integrated system.


Asunto(s)
Espectrometría de Masas de Intercambio de Hidrógeno-Deuterio/métodos , Descubrimiento de Drogas/economía , Descubrimiento de Drogas/instrumentación , Descubrimiento de Drogas/métodos , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Análisis de Inyección de Flujo/métodos , Humanos , Espectrometría de Masas de Intercambio de Hidrógeno-Deuterio/economía , Espectrometría de Masas de Intercambio de Hidrógeno-Deuterio/instrumentación , Ligandos , Proteínas/química
3.
Anal Chim Acta ; 1073: 54-61, 2019 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-31146836

RESUMEN

This work presents a cost-effective and simple flow injection analysis (FIA) system for simultaneous and direct determination of urea and creatinine in human urine. The FIA system comprises two in-house detectors, a contactless conductivity detector and a light emitting diode (LED) detector. The contactless detector was built as a flow-through detection cell with axial electrodes, commonly known as capacitively coupled contactless conductivity detector (C4D) and the diode detector was fabricated based on the concept of paired emitter detector diodes (PEDD). With appropriate dilution of urine, the sample is directly injected into a stream of glycine-NaOH buffer pH 8.8 (the gas donor stream) and is carried by the carrier through a urease minicolumn for on-line enzymatic hydrolysis. The generated NH3 diffuses from the carrier stream through a porous polytetrafluoroethylene (PTFE) membrane into a stream of deionized water (the acceptor stream) leading to an increase in the signal at the C4D due to the NH3 dissolution in the water. In this system, creatinine is determined based on the Jaffé reaction by merging a stream of alkaline picrate with the gas donor stream. The change in color is detected using the PEDD equipped with two green LEDs. Under the optimum condition, the linear range of urea and creatinine were 30-240 mg L-1 and 10-500 mg L-1, with limits of detection of 9.0 mg L-1 and 0.9 mg L-1, respectively. The proposed system provides satisfactorily good precision (RSD < 3%), with sample throughput of 31 sample h-1 for the two analytes. The FIA system tolerates potential interference commonly found in human urine. The system was successfully applied and validated with selected reference methods.


Asunto(s)
Colorimetría/economía , Creatinina/orina , Análisis de Inyección de Flujo/economía , Urea/orina , Conductividad Eléctrica , Humanos
4.
Spectrochim Acta A Mol Biomol Spectrosc ; 222: 117177, 2019 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-31176150

RESUMEN

A novel, rapid and convenient competitive immunoassay for ultrasensitive detection of chloramphenicol residues in shrimp and honey was established combined with flow injection chemiluminescence. The carboxylic resin beads were used as solid phase carriers to load with more coating antigen due to their larger specific surface area and good biocompatibility. The surface of the silica dioxide nanoparticles was modified with aldehyde group to combine with more horseradish peroxidase and the chloramphenicol antibody. There was a competitive process between the chloramphenicol in solution and the immobilized coating antigen to combine with the limited binding site of antibody to form the immunocomplex. Silica dioxide nanoparticles played an important role in enhancing chemiluminescence signal, because the horseradish peroxidase on SiO2 effectively catalyzed the system of luminol-PIP-H2O2. Under optimal conditions, the chemiluminescence intensity decreased linearly with the logarithm of the chloramphenicol concentration in the range of 0.0001 to 100 ng mL-1 and the detection limit (3σ) was 0.033 pg mL-1. This immunosensor demonstrated acceptable stability, high specificity and reproducibility. The horseradish peroxidase-silica dioxide nanoparticle-chloramphenicol antibody complex successfully prepared in this article was firstly applied to the detection of chloramphenicol, and had extremely important meanings for the application of nanoparticles and enzymatic catalysis in the field of chemiluminescence.


Asunto(s)
Antibacterianos/análisis , Cloranfenicol/análisis , Análisis de los Alimentos/instrumentación , Mediciones Luminiscentes/instrumentación , Nanopartículas/química , Dióxido de Silicio/química , Animales , Anticuerpos Monoclonales/química , Técnicas Biosensibles/economía , Técnicas Biosensibles/instrumentación , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Análisis de los Alimentos/economía , Miel/análisis , Inmunoensayo/economía , Inmunoensayo/instrumentación , Límite de Detección , Mediciones Luminiscentes/economía , Penaeidae/química , Reproducibilidad de los Resultados , Resinas Sintéticas/química , Mariscos/análisis
5.
Acta Crystallogr D Struct Biol ; 75(Pt 2): 160-177, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-30821705

RESUMEN

Highly efficient data-collection methods are required for successful macromolecular crystallography (MX) experiments at X-ray free-electron lasers (XFELs). XFEL beamtime is scarce, and the high peak brightness of each XFEL pulse destroys the exposed crystal volume. It is therefore necessary to combine diffraction images from a large number of crystals (hundreds to hundreds of thousands) to obtain a final data set, bringing about sample-refreshment challenges that have previously been unknown to the MX synchrotron community. In view of this experimental complexity, a number of sample delivery methods have emerged, each with specific requirements, drawbacks and advantages. To provide useful selection criteria for future experiments, this review summarizes the currently available sample delivery methods, emphasising the basic principles and the specific sample requirements. Two main approaches to sample delivery are first covered: (i) injector methods with liquid or viscous media and (ii) fixed-target methods using large crystals or using microcrystals inside multi-crystal holders or chips. Additionally, hybrid methods such as acoustic droplet ejection and crystal extraction are covered, which combine the advantages of both fixed-target and injector approaches.


Asunto(s)
Cristalografía por Rayos X/instrumentación , Rayos Láser , Acústica/instrumentación , Animales , Cristalización/economía , Cristalización/instrumentación , Cristalografía por Rayos X/economía , Electrones , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Humanos , Proteínas/química , Factores de Tiempo
6.
J Pharm Biomed Anal ; 149: 179-184, 2018 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-29121572

RESUMEN

A green, simple, accurate and highly sensitive sequential injection lab-at-valve procedure has been developed for the simultaneous determination of ascorbic acid (Asc) and rutin using 18-molybdo-2-phosphate Wells-Dawson heteropoly anion (18-MPA). The method is based on the dependence of the reaction rate between 18-MPA and reducing agents on the solution pH. Only Asc is capable of interacting with 18-MPA at pH 4.7, while at pH 7.4 the reaction with both Asc and rutin proceeds simultaneously. In order to improve the precision and sensitivity of the analysis, to minimize reagent consumption and to remove the Schlieren effect, the manifold for the sequential injection analysis was supplemented with external reaction chamber, and the reaction mixture was segmented. By the reduction of 18-MPA with reducing agents one- and two-electron heteropoly blues are formed. The fraction of one-electron heteropoly blue increases at low concentrations of the reducer. Measurement of the absorbance at a wavelength corresponding to the isobestic point allows strictly linear calibration graphs to be obtained. The calibration curves were linear in the concentration ranges of 0.3-24mgL-1 and 0.2-14mgL-1 with detection limits of 0.13mgL-1 and 0.09mgL-1 for rutin and Asc, respectively. The determination of rutin was possible in the presence of up to a 20-fold molar excess of Asc. The method was applied to the determination of Asc and rutin in ascorutin tablets with acceptable accuracy and precision (1-2%).


Asunto(s)
Ácido Ascórbico/análisis , Análisis de Inyección de Flujo/métodos , Indicadores y Reactivos/química , Rutina/análisis , Aniones/química , Ácido Ascórbico/química , Calibración , Química Farmacéutica/economía , Química Farmacéutica/instrumentación , Química Farmacéutica/métodos , Combinación de Medicamentos , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Concentración de Iones de Hidrógeno , Límite de Detección , Molibdeno/química , Ácidos Fosfóricos/química , Rutina/química , Sensibilidad y Especificidad , Comprimidos/análisis , Comprimidos/química
7.
Anal Bioanal Chem ; 408(22): 6201-11, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27379391

RESUMEN

A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 µg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 µg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption.


Asunto(s)
Antibacterianos/aislamiento & purificación , Suplementos Dietéticos/análisis , Huevos/análisis , Análisis de los Alimentos/métodos , Microextracción en Fase Líquida/métodos , Sonicación/métodos , Tetraciclinas/aislamiento & purificación , Antibacterianos/análisis , Cromatografía Líquida de Alta Presión/economía , Cromatografía Líquida de Alta Presión/instrumentación , Cromatografía Líquida de Alta Presión/métodos , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Análisis de Inyección de Flujo/métodos , Contaminación de Alimentos/análisis , Límite de Detección , Microextracción en Fase Líquida/economía , Microextracción en Fase Líquida/instrumentación , Sonicación/economía , Sonicación/instrumentación , Tetraciclinas/análisis
8.
Anal Bioanal Chem ; 408(7): 1871-8, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26780708

RESUMEN

The present study demonstrates the suitability of direct UV detection for saccharide analysis in HPLC. Under highly alkaline conditions, the non-UV absorbing saccharides are converted by a photo-initiated chemical reaction in the detection cell into malonenolate, which can be detected at 266 nm. A straightforward method for such direct UV detection of saccharides after their separation by anion-exchange chromatography was developed and successfully applied to several beverage samples. Investigation and optimization of the influencing factors using design of experiment resulted in a baseline separation of glucose, fructose, and sucrose within 6 min and LOD values below 0.2 mg L(-1). In addition, a fast, simple and cost-effective flow injection method was developed to estimate the total saccharide concentration. The results of this method applied to beverage samples are in good agreement with the chromatographic method as well as to the saccharide concentration stated by the manufacturer. Finally, a comparison of different commercially available UV detectors and detector cells revealed that sensitive detection requires the use of recently introduced flow cells with extended path length.


Asunto(s)
Bebidas/análisis , Carbohidratos/análisis , Cromatografía Líquida de Alta Presión/instrumentación , Cromatografía Líquida de Alta Presión/economía , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Análisis de los Alimentos/economía , Análisis de los Alimentos/instrumentación , Límite de Detección , Rayos Ultravioleta
9.
Artículo en Inglés | MEDLINE | ID: mdl-26724494

RESUMEN

A sensitive, rapid and simple flow-injection chemiluminescence (CL) system based on the light emitted from KMnO4-cadmium sulfide quantum dots (CdS QDs) reaction in the presence of cetyltrimethylammonium bromide (CTAB) in acidic medium was developed as a CL probe for the sensitive determination of atenolol. Optical and structural features of CdS QDs capped with l-cysteine, which synthesized via hydrothermal approach, were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and UV-Vis spectroscopy. The CL intensity of KMnO4-CdS QDs-CTAB was remarkably enhanced in the presence of trace level of atenolol. Under optimum experimental conditions, there is a linear relationship between the increase in CL intensity of KMnO4-CdS QDs-CTAB system and atenolol concentration in a range of 0.001 to 4.0 mg L(-1) and 4.0 to 18.0 mg L(-1), with a detection limit (3σ) of 0.0010 mg L(-1). A possible mechanism for KMnO4-CdS QDs-CTAB-atenolol CL reaction is proposed. To prove the practical application of the KMnO4-CdS QDs-CTAB CL method, the method was applied for the determination of atenolol in spiked environmental water samples and commercial pharmaceutical formulation. Furthermore, corona discharge ionization ion mobility spectrometry (CD-IMS) technique was utilized for determination of atenolol.


Asunto(s)
Antihipertensivos/análisis , Atenolol/análisis , Compuestos de Cadmio/química , Análisis de Inyección de Flujo/métodos , Mediciones Luminiscentes/métodos , Puntos Cuánticos/química , Sulfuros/química , Contaminantes Químicos del Agua/análisis , Cetrimonio , Compuestos de Cetrimonio/química , Análisis de Inyección de Flujo/economía , Límite de Detección , Luminiscencia , Mediciones Luminiscentes/economía , Preparaciones Farmacéuticas/química , Permanganato de Potasio/química , Puntos Cuánticos/ultraestructura , Agua/análisis
10.
Talanta ; 144: 868-74, 2015 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-26452902

RESUMEN

Various metal nanoparticles (NPs) decorated on carbon nanotube (CNT) was modified on the home-made screen printed carbon electrode (SPCE) in order to enhances sensitivity of hydrogen peroxide (H2O2) determination. The simple casting method was used for the electrode modification. The monometallic and bimetallic NPs modified electrodes were investigated for their electrochemical properties for H2O2 reduction. The Pd-CNT/SPCE is appropriated to measure the H2O2 reduction at a potential of -0.3 V, then this modified electrode was incorporated with a home-made flow through cell and applied in a simple flow injection amperometry (FI-Amp). Some parameters influencing the resulted modified electrode and the FI-Amp system were studied. The proposed detection system was able to detect H2O2 in the range of 0.1-1.0 mM, with detection limit of 20 µM. Relative standard deviation for 100 replicated injections of 0.6 mM H2O2 was 2.3%. The reproducibility of 6 electrodes preparing in 3 different lots was 8.2%. It was demonstrated for determination of H2O2 in disinfectant, hair colorant and milk samples. Recoveries in the range of 90-109% were observed. The developed system provided high stability, good repeatability, high sample throughput and low reagent consumption.


Asunto(s)
Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/métodos , Peróxido de Hidrógeno/análisis , Límite de Detección , Nanopartículas del Metal/química , Nanotubos de Carbono/química , Impresión , Electroquímica , Electrodos , Análisis de Inyección de Flujo/instrumentación , Peróxido de Hidrógeno/química , Reproducibilidad de los Resultados , Factores de Tiempo
11.
Biosens Bioelectron ; 64: 639-49, 2015 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-25441413

RESUMEN

Time-resolved visualization and analysis of slow dynamic processes in living cells has revolutionized many aspects of in vitro cellular studies. However, existing technology applied to time-resolved live-cell microscopy is often immobile, costly and requires a high level of skill to use and maintain. These factors limit its utility to field research and educational purposes. The recent availability of rapid prototyping technology makes it possible to quickly and easily engineer purpose-built alternatives to conventional research infrastructure which are low-cost and user-friendly. In this paper we describe the prototype of a fully automated low-cost, portable live-cell imaging system for time-resolved label-free visualization of dynamic processes in living cells. The device is light-weight (3.6 kg), small (22 × 22 × 22 cm) and extremely low-cost (<€1250). We demonstrate its potential for biomedical use by long-term imaging of recombinant HEK293 cells at varying culture conditions and validate its ability to generate time-resolved data of high quality allowing for analysis of time-dependent processes in living cells. While this work focuses on long-term imaging of mammalian cells, the presented technology could also be adapted for use with other biological specimen and provides a general example of rapidly prototyped low-cost biosensor technology for application in life sciences and education.


Asunto(s)
Técnicas de Cultivo de Célula/instrumentación , Separación Celular/instrumentación , Análisis de Inyección de Flujo/instrumentación , Micromanipulación/instrumentación , Microscopía/instrumentación , Manejo de Especímenes/instrumentación , Fracciones Subcelulares/diagnóstico por imagen , Reactores Biológicos/economía , Técnicas de Cultivo de Célula/economía , Separación Celular/economía , Diseño de Equipo , Análisis de Falla de Equipo , Análisis de Inyección de Flujo/economía , Células HEK293 , Humanos , Micromanipulación/economía , Microscopía/economía , Miniaturización , Manejo de Especímenes/economía , Ultrasonografía
12.
Talanta ; 133: 88-93, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25435232

RESUMEN

A new, fast, automated and inexpensive sample pre-treatment method for (99)Tc determination by inductively coupled plasma-mass spectrometry (ICP-MS) detection is presented. The miniaturized approach is based on a lab-on-valve (LOV) system, allowing automatic separation and preconcentration of (99)Tc. Selectivity is provided by the solid phase extraction system used (TEVA resin) which retains selectively pertechnetate ion in diluted nitric acid solution. The proposed system has some advantages such as minimization of sample handling, reduction of reagents volume, improvement of intermediate precision and sample throughput, offering a significant decrease of both time and cost per analysis in comparison to other flow techniques and batch methods. The proposed LOV system has been successfully applied to different samples of environmental interest (water and soil) with satisfactory recoveries, between 94% and 98%. The detection limit (LOD) of the developed method is 0.005 ng. The high durability of the resin and its low amount (32 mg), its good intermediate precision (RSD 3.8%) and repeatability (RSD 2%) and its high extraction frequency (up to 5 h(-1)) makes this method an inexpensive, high precision and fast tool for monitoring (99)Tc in environmental samples.


Asunto(s)
Monitoreo del Ambiente/instrumentación , Contaminantes Radiactivos/aislamiento & purificación , Suelo/química , Extracción en Fase Sólida/instrumentación , Tecnecio/aislamiento & purificación , Agua/análisis , Monitoreo del Ambiente/economía , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Límite de Detección , Espectrometría de Masas/economía , Espectrometría de Masas/instrumentación , Contaminantes Radiactivos/análisis , Extracción en Fase Sólida/economía , Tecnecio/análisis
13.
Crit Rev Anal Chem ; 44(3): 220-32, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25391562

RESUMEN

Sequential injection chromatography was proposed in 2003 to perform a simple, rapid, reagent-saving, environmentally benign, on-site, and instrumentally inexpensive separation procedure. Sequential injection chromatography is a version of sequential injection analysis, which is the second generation in the family of flow injection techniques. Despite its advantages over high-performance liquid chromatography, sequential injection chromatography has confronted some challenges. Furthermore, the applications of sequential injection chromatography in its first five years are almost all limited to pharmaceutical analysis. Interestingly, in its second five years, various developments in sequential injection chromatography technology were achieved. The developments have enhanced the efficiency of sequential injection chromatography and hence its applications have extended to biological, food, and environmental analyses. The main objectives of this review are to examine recent developments (2008-2013) in sequential injection chromatography and to describe how these developments improve the efficiency of the technology. The sequential injection chromatography methodologies reported during that period are also discussed along with controlling conditions and analytical results. The review also describes the principles, instrumentation, and procedure behind sequential injection chromatography.


Asunto(s)
Cromatografía Liquida/instrumentación , Análisis de Inyección de Flujo/instrumentación , Cromatografía Liquida/economía , Cromatografía Liquida/métodos , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/métodos , Tecnología Química Verde , Factores de Tiempo
14.
Electrophoresis ; 35(16): 2361-9, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-24931388

RESUMEN

Here, we describe an improved high-speed CE (HSCE) system using a short capillary and translational spontaneous sample injection. Several important factors for consideration in system design as well as various factors influencing the performance of the HSCE system were investigated in detail. The performance of this HSCE system was demonstrated in electrophoretic separation of FITC-labeled amino acids. Under optimized conditions, baseline separation of eight amino acids and FITC were achieved in 21 s with the plate heights ranging from 0.20 to 0.31 µm, corresponding to a separation rate up to 20 700 theoretical plates per second. The separation speed and efficiency of the optimized high-speed CE system are comparable to or even better than those reported in microchip-based CE systems.


Asunto(s)
Electroforesis Capilar/instrumentación , Aminoácidos/aislamiento & purificación , Electroforesis Capilar/economía , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Fluoresceína-5-Isotiocianato/aislamiento & purificación , Tamaño de la Muestra , Factores de Tiempo
15.
Biosens Bioelectron ; 51: 143-9, 2014 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-23948245

RESUMEN

A novel, simple, rapid, selective and sensitive method for the determination of neostigmine (Ns) ion in its bulk powder, different pharmaceutical dosage forms, and biological fluids (plasma and urine) using four modified carbon paste electrodes was developed. Sensor 1 is based on ion-association Ns-TPB, sensor 2 used Ns-PT, sensor 3 comprises a mixture of (Ns-PT+Ns-TPB) and sensor 4 was constructed using (Ns-PT+ß-CD). Solvent mediator 2-NPPE exhibited a proper behavior including Nernstian slope ranging from 61.5±0.5 to 64.5±0.5 mV per decade over the pH range of 3.8-10 for the four sensors. Linear responses of Ns within the concentration range 1.0×10(-7)-1.0×10(-2) mol/L were obtained. The response time is very short (≤10s) with a detection limit 6.3×10(-8) M. In flow injection analysis (FIA), sensor 3 shows a Nernstian slope value 75.5±0.5 mV per decade within the concentration range of 1×10(-6)-1×10(-2) mol/L and with a detection limit 7.5×10(-7) mol/L. The utility of mixed or additives of ß-CD had a significant influence on increasing the sensitivity of sensors 3 and 4 compared to sensors 1 and 2. The sensors were applied for the determination of neostigmine (Ns) ion in its bulk powder, different pharmaceutical dosage forms, and biological fluids (plasma and urine). The results obtained were satisfactory with excellent percentage recovery comparable with official method for the assay based on non-aqueous titration using perchloric acid as a titrant.


Asunto(s)
Técnicas Biosensibles/instrumentación , Carbono/química , Inhibidores de la Colinesterasa/sangre , Inhibidores de la Colinesterasa/orina , Neostigmina/sangre , Neostigmina/orina , Técnicas Biosensibles/economía , Inhibidores de la Colinesterasa/análisis , Electrodos , Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/instrumentación , Humanos , Límite de Detección , Neostigmina/análisis , Preparaciones Farmacéuticas/química , Potenciometría/economía , Potenciometría/instrumentación
16.
Analyst ; 138(6): 1772-8, 2013 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-23364279

RESUMEN

The response of many previously low-detectable or undetectable compounds in electrospray ionization mass spectrometry (ESI-MS) has been enhanced by the addition of a simple, homemade needle into the traditional ESI interface. The needle located between the ESI emitter and the ion sweep cone (inlet of the detector) would ionize those neutral gaseous compounds, formed during electrospray, by a corona discharge process. The mobile phases, ESI parameters and positions of the needle were investigated and optimized. Several groups of compounds and herbal extracts were tested using the homemade set-up. Both the results of the flow injection and the hyphenated MS analyses showed significant enhancement effects of our homemade needle. The advantages of the proposed method include low cost, simplicity and practicality.


Asunto(s)
Análisis de Inyección de Flujo/instrumentación , Espectrometría de Masa por Ionización de Electrospray/instrumentación , Diseño de Equipo , Análisis de Inyección de Flujo/economía , Agujas , Extractos Vegetales/química , Plantas Medicinales/química , Espectrometría de Masa por Ionización de Electrospray/economía
17.
J Biotechnol ; 163(4): 371-6, 2013 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-22465601

RESUMEN

A microfluidic chip integrating amperometric enzyme sensors for the detection of glucose, glutamate and glutamine in cell-culture fermentation processes has been developed. The enzymes glucose oxidase, glutamate oxidase and glutaminase were immobilized by means of cross-linking with glutaraldehyde on platinum thin-film electrodes integrated within a microfluidic channel. The biosensor chip was coupled to a flow-injection analysis system for electrochemical characterization of the sensors. The sensors have been characterized in terms of sensitivity, linear working range and detection limit. The sensitivity evaluated from the respective peak areas was 1.47, 3.68 and 0.28 µAs/mM for the glucose, glutamate and glutamine sensor, respectively. The calibration curves were linear up to a concentration of 20 mM glucose and glutamine and up to 10 mM for glutamate. The lower detection limit amounted to be 0.05 mM for the glucose and glutamate sensor, respectively, and 0.1 mM for the glutamine sensor. Experiments in cell-culture medium have demonstrated a good correlation between the glutamate, glutamine and glucose concentrations measured with the chip-based biosensors in a differential-mode and the commercially available instrumentation. The obtained results demonstrate the feasibility of the realized microfluidic biosensor chip for monitoring of bioprocesses.


Asunto(s)
Técnicas Biosensibles , Catalasa/metabolismo , Análisis de Inyección de Flujo/métodos , Glucosa Oxidasa/metabolismo , Glutaminasa/metabolismo , Técnicas Biosensibles/economía , Técnicas Biosensibles/instrumentación , Técnicas Biosensibles/métodos , Calibración , Técnicas Electroquímicas/economía , Técnicas Electroquímicas/instrumentación , Electrodos , Fermentación , Análisis de Inyección de Flujo/economía , Glucosa/análisis , Ácido Glutámico/análisis , Glutamina/análisis
18.
Talanta ; 99: 883-9, 2012 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-22967638

RESUMEN

A single-line flow injection system and multiple pulse amperometric detection using a boron-doped diamond electrode were employed to develop and optimize a simple, low-cost, and rapid method for the simultaneous determination of two pairs of food colorants: tartrazine and sunset yellow (TT-SY) or brilliant blue and SY (BB-SY). A dual-potential waveform was used: E(det.1)=-150 mV (400 ms duration) and E(det.2)=-450 mV (100 ms duration) vs. Ag/AgCl (3.0 mol L(-1) KCl). Polarization at E(det.1) or E(det.2) causes reduction of SY or the respective pair of colorants, TT-SY or BB-SY; hence, with proper current correction, both colorants in each pair can be determined. The obtained linear response ranges (detection limits) were 5.0-60.0 (2.5) and 1.0-50.0 (0.80) µmol L(-1), for TT and SY, or 5.0-60.0 (3.5) and 1.0-50.0 (0.85) µmol L(-1), for BB and SY, respectively. Investigation of possible interferents (other food colorants or additives) showed no significant interference with the methods here proposed, which were then used to simultaneously determine the pairs of colorants in industrialized food samples, with results that showed good agreement with those obtained using a comparative HPLC method.


Asunto(s)
Boro/química , Diamante/química , Electroquímica/instrumentación , Análisis de Inyección de Flujo/métodos , Colorantes de Alimentos/análisis , Contaminación de Alimentos/análisis , Electroquímica/economía , Electrodos , Análisis de Inyección de Flujo/economía , Colorantes de Alimentos/química , Factores de Tiempo
19.
Anal Sci ; 28(7): 651-6, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22790365

RESUMEN

A simple and inexpensive method for fabricating a microfluidic platform was developed. A printed circuit board (PCB) was used to make a master mold for replicating a polydimethylsiloxane (PDMS) microchannel. The master mold was fabricated by a simple photolithographic method, employing a photoresist dry film. The process did not use hazardous chemicals, a clean room or any expensive instrument. The PDMS microchannel was clamped with polymethylmethacrylate (PMMA) plates, where a light emitting diode (LED) as a light source and a light dependent resistor (LDR) as a light sensor were attached to form a simple optical sensor. The system was successfully employed as a micro flow injection analysis for the determination of glutathione in dietary supplement samples. A linear calibration graph in the range of 5.0 - 60.0 mg L(-1) glutathione was obtained with a detection limit of 0.01 mg L(-1). The system provided a sample throughput of 48 h(-1), with microliter consumption of the reagent.


Asunto(s)
Colorimetría/instrumentación , Análisis de Inyección de Flujo/instrumentación , Glutatión/análisis , Técnicas Analíticas Microfluídicas/métodos , Fenómenos Ópticos , Integración de Sistemas , Colorimetría/economía , Cobre/química , Análisis Costo-Beneficio , Suplementos Dietéticos/análisis , Equipos y Suministros Eléctricos , Análisis de Inyección de Flujo/economía , Técnicas Analíticas Microfluídicas/instrumentación
20.
Talanta ; 96: 121-6, 2012 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-22817938

RESUMEN

Two miniature, fibreless, compact and highly integrated flow-through optoelectronic detectors dedicated for photometric and fluorimetric determination of proteins have been developed. Both detectors operating according to paired-emitter-detector-diode methodology are constructed only of light emitting diodes and therefore their total cost is extremely low. The photometric detector is dedicated for protein determination according to Bradford method based on detection of protein adduct with Coomassie Brilliant Blue. The fluorimetric detector allows determination of proteins after reaction with fluorescamine. Both developed detectors have been incorporated into economic flow systems constructed of microsolenoid valves and pumps. The resulting multicommutated/multipumping flow analysis systems enable detection of albumins and globulins at ppm levels, thus they are useful for protein determination in diluted samples of physiological fluids.


Asunto(s)
Análisis de Inyección de Flujo/economía , Análisis de Inyección de Flujo/métodos , Fluorometría/economía , Fluorometría/métodos , Fenómenos Ópticos , Proteínas/análisis , Animales , Bovinos , Humanos , Proteínas/química
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