Simultaneous analysis of saturated and unsaturated fatty acids present in pequi fruits by capillary electrophoresis

In the current study, an alternative method has been proposed for simultaneous analysis of palmitic, stearic, oleic, linoleic, and linolenic acids by capillary zone electrophoresis (CZE) using indirect detection. The background electrolyte (BGE) used for the analysis of these fatty acids (FAs) consisted of 15.0 mmol L−1 NaH2PO4/Na2HPO4 at pH 6.86, 4.0 mmol L−1 SDBS, 8.3 mmol L−1 Brij 35, 45% v/v acetonitrile (can), and 2.1% n-octanol. The FAs quantification of FAs was performed using a response factor approach, which provided a high analytical throughput for the real sample. The CZE method, which was applied successfully for the analysis of pequi pulp, has advantages such as short analysis time, absence of lipid fraction extraction and derivatization steps, and no significant difference in the 95% confidence intervals for FA quantification results, compared to the gas chromatography official method (AOCS Ce 1h-05).

Allelopathic potential and systematic evaluation of secondary compounds in extracts from roots of Canavalia ensiformis by capillary electrophoresis

Organic extracts were obtained from roots of Canavalia ensiformis and evaluated for allelopathic potential on the germination of the weed seeds: Mimosa pudica, Cassia tora and Cassia occidentalis showing a strong allelopathic potential. After that, a systematic study of these crude extracts was made using specific protocols developed in capillary electrophoresis (CE) in order to determine some classes of secondary metabolites. Capillary electrophoresis protocols were highly specific, which makes it possible to identify 5 classes of compounds using the same crude extract samples and analyze them fartly. Some of the compounds identified show activity in the inhibition of seeds germination.

Comparison of Potassium and Sodium Content in Diet and Non-Diet Soft Drinks by Using Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection

Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C4D) was used for determination of sodium and potassium concentrations in diet and non-diet soft drinks. Higher sodium concentrations were found in the diet samples due to the utilization of sodium salts of cyclamate and saccharine as sweeteners. The CE-C4D method can be used by food industries and health regulatory agencies for monitoring sodium and potassium content, not only in soft drink but in many others food products.

Comparison of capillary electrophoresis and high performance liquid chromatography methods for caffeine determination in decaffeinated coffee

Decaffeinated coffee accounts for 10 percent of coffee sales in the world; it is preferred by consumers that do not wish or are sensitive to caffeine effects. This article presents an analytical comparison of capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) methods for residual caffeine quantification in decaffeinated coffee in terms of validation parameters, costs, analysis time, composition and treatment of the residues generated, and caffeine quantification in 20 commercial samples. Both methods showed suitable validation parameters. Caffeine content did not differ statistically in the two different methods of analysis. The main advantage of the high performance liquid chromatography (HPLC) method was the 42-fold lower detection limit. Nevertheless, the capillary electrophoresis (CE) detection limit was 115-fold lower than the allowable limit by the Brazilian law. The capillary electrophoresis (CE) analyses were 30% faster, the reagent costs were 76.5-fold, and the volume of the residues generated was 33-fold lower. Therefore, the capillary electrophoresis (CE) method proved to be a valuable analytical tool for this type of analysis.

Molecular characterization of grapevine from Santa Catarina, Brazil, using microsatellite markers

The objective of this work was to characterize the grape germplasm in Santa Catarina, Brazil, using microsatellite DNA markers (simple sequence repeats - SSR). The DNA samples were collected from leaves and shoots of accessions of public and private collections from the counties Urussanga, Nova Trento, Rodeio, São Joaquim, Campos Novos, Videira, and Água Doce. Ten SSR loci (VVS2, VVMD5, VVMD7, VVMD27, VrZAG62, VrZAG79, VVMD25, VVMD28, VVMD31, and VVMD32) were analysed by capillary electrophoresis. Molecular profiling was conducted for 190 grapevines (European, American, and hybrids), and 67 genotypes were obtained. The data were compared with each other and with those from the literature and from online databases, in order to identify varieties and discover cases of synonymy and homonymy. Forty molecular profiles corresponded to known varieties, while 27 genotypes were described for the first time. The existence of typical germplasm composed mainly of American and hybrid varieties is an important finding for local viticulture. Applications of the results rely on quality control and certification at the nursery level. Increasing precision in the characterization of grapevine genotypes may help breeding programs.

Mecanismos de Separação em Eletroforese Capilar

Since its inception in the 80's, capillary electrophoresis has matured into a well established technique for the separation and analysis of complex samples. One of its strongest aspects is the ability to handle materials from a diversity of chemical classes, ranging from few to millions of Daltons. This is only possible because several modes of electrophoresis can be performed in a single capillary format. In this work, relevant aspects of capillary zone electrophoresis in its three modes (free solution, micellar and gel), capillary isoelectric focusing and capillary isotachophoresis are discussed and many representative applications are presented.

Determinação simultânea de ânions por eletroforese capilar: características e aplicações

Capillary electrophoresis (CE) encompasses a number of characteristics quite suitable for the simultaneous analysis of small ions such as high efficiency and resolving power, directly associated to its impressively high peak capacity, and short analysis time. In appropriate conditions, it is possible to perform the separation of approximately 36 anions in less than 3 minutes. In this work, the mechanisms by which anion analysis is performed was criteriously discussed, and a thorough review of the literature in the past 5 years, focusing mostly in applications of CE to anion analysis in real matrices, was presented.

Implementação de um sistema de eletroforese capilar com detecção de fluorescência induzida por laser

A capillary electrophoresis system using laser induced fluorescence detection is described. A Raman system equipped with a microscope has been used to focus the laser beam on the capillary giving a lateral resolution of 1.5 mm. The fluorescence signal of the analyte (ZnPcTS - tetrasulfonated zinc-phthalocyanine) was collected by the microscope objectives and analysed by a monochromator with confocal characteristics equipped with a CCD detector. Electropherograms obtained with this system were compared to those obtained on a commercial instrument, showing that the described system presents a lower detection limit and better resolution.

Determinação simultânea de cátions por eletroforese capilar: fundamentos e aplicações

In this work, the analysis of cations by capillary electrophoresis is reviewed from the theoretical and practical point of view. Separation mechanisms and detection modes are discussed and illustrated. A thorough compilation of the literature over the last ten years, regarding applications of the technique to the analysis of cations in real matrices, is presented.

Sistemas interfaceados de análise por injeção em fluxo e eletroforese capilar (FIA - CE): desafios, aplicações e perspectivas

A review about the state-of-the-art of flow injection analysis (FIA) -- capillary electrophoresis (CE) systems is presented. The basic principles of flow injection and capillary electrophoresis are briefly revised. The main aspects of the FIA-CE hybridization, including advantages and shortcomings, are discussed. Some applications involving all different designs are also presented. This review covers the literature from 1997 up to 2000.

Detecção eletroquímica em eletroforese capilar

This review focuses the development of electrochemical detection systems coupled to capillary electrophoresis. Conductometric, amperometric, voltametric, and potentiometric modes of detection are reviewed. The positioning of the electrodes, interferences of high electric field, and the materials employed in the fabrication and modification of the electrodes are discussed. The advantages of the use of electrochemical detection with capillary electrophoresis, regarding to the sensitivity and selectivity, is exemplified with a large number of applications. Also, the use of electrochemical detection systems in microchip technology is addressed.

Eletroforese capilar acoplada à espectrometria com plasma: uma ferramenta eficiente para a especiação

The most important features of the CE-ICP hyphenation, as well as its advantages and drawbacks as a tool for speciation are discussed. The fundamental principles of capillary electrophoresis and inductively coupled plasma mass spectrometry are also presented. Some applications involving different designs proposed in the literature to couple CE and ICP system for elemental speciation are reviewed.

Análise de ácidos graxos por eletroforese capilar utilizando detecção condutométrica sem contato

This article describes a novel approach to the separation of fatty acids ranging from 8 to 20 carbons using capillary electrophoresis with contactless conductivity detection. Complete separation of nine linear chain fatty acids (from C8:0 to C20:0) was achieved in 15 min under normal polarity operation. Limits of detection ranged from 35 to 319 µmol L-1 for C20:0 to C8:0, respectively. The optimized running electrolyte composition was 5.0 mmol L-1 phosphate buffer at pH 7, 4.0 mmol L-1 dimethyl-b-cyclodextrin, 2.0 mmol L-1 trimethyl-b-cyclodextrin, acetonitrile 50% (v/v), and methanol 20% (v/v). The applicability of the separation system was demonstrated by the analysis of coconut vegetable oil.

Multímetro interfaceado de baixo custo para aquisição de dados

A digital multimeter (~U$ 240.00 on the national market) connected to a microcomputer by a RS-232 serial interface is proposed for data acquisition in equipment with analog output. Data are measured at the rate of 2 points per second and stored in text files by the software that accompanies the device, running in a Windows environment. The performance of the multimeter was verified by monitoring the transient signals generated in flow injection systems associated with fluorimetric, spectrophotometric and flame photometric detection. In addition, the performance of the proposed device was similar to that attained by employing an interface card with a 12-bit analog-to-digital converter for acquisition of the signals generated by a capillary electrophoresis equipment with oscillometric detection.

Métodos para análise de ácido clorogênico

This paper describes the analytical methods for determination of total chlorogenic acid (CGA) and their individual isomers. Spectrofotometric methods are adequate for total CGA analysis in green coffee but they can provide inflated results for coffee products. High pressure liquid chromatography (HPLC) with gel permeation column and ultraviolet (UV) monitoring is adequate for the simultaneous analysis of total CGA, alkaloids and sugars in coffee products. HPLC-UV-reversed phase is a simple, rapid and precise method for the determination of the individual isomers of CGA. Gas chromatography (GC) also is applied to the analysis of the individual isomers but phenolic acids need to be derivatized before analysis. Both HPLC- and GC-mass spectrometry provide an unequivocal identification of the individual isomers. The capillary electrophoresis method is simple, rapid and adequate to the simultaneous analysis of polyphenols and xanthines. Advantages and limitations of each method are discussed throughout the text.