Fatty acids analysis by capillary electrophoresis: Fundamentals, advantages and applications.

This review covers the know-how of the Grupo de Química Analítica e Quimiometria regarding the analysis of fatty acids by capillary electrophoresis acquired over its 20 years of existence. Therefore, the fundamentals, advantages, and applications of this technique for analyzing different fatty acids in samples such as food, oils, cosmetics, and biological matrices are presented and discussed. Capillary electrophoresis is, thus, shown as an interesting and valuable separation technique for the target analysis of these analytes as an alternative to the gas chromatography coupled to flame ionization detection, as it offers advantages over the latter such as low analysis times, low sample and reagent consumption, the use of a nondedicated column, and simpler sample preparation. In addition, the methods shown in this literature review can be useful for quality control, adulteration, and health-related research by regulatory agencies.

Capillary electrophoresis in association with chemometrics approach for bitterness hop (Humulus lupulus L.) classification.

The precursor compounds related to the bitterness of beer are called α-acids. These compounds are extracted from the hop, which is an important ingredient in the brewing process. These compounds were analyzed by capillary electrophoresis. The electrophoretic method used 160 mmol/L of ammonium carbonate (pH 9) as BGE (background electrolyte), a voltage of +20 kV in a capillary with 50 µm of internal diameter and with a 62.5 cm of total length (54 cm effective). The samples were injected in hydrodynamic mode applying a pressure of 25 mbar for 5 s and the analytes were detected at 230 nm. A hydromethanolic extraction during 3 h was considered as the optimum condition for the sample preparation using MeOH/H2 O 80:20 v/v as the extract solution. From the optimized conditions the electropherograms were evaluated for their use as input for chemometric modeling. Preprocessing investigation for electrophoretic data taking into account the alignment, denoising and baseline correction, and variable selection were considered before the chemometric modeling using principal component analysis (PCA). The electrophoretic data were systematically evaluated to find the optimum conditions to modeling. A PCA analysis for all tests was carried out using different preprocessing methods and, an explained variance higher than 90% was achieved in all of them. The optimized chemometric method worked with aligned and meancentered data. From this approach, a simple and efficient method to classify hop samples with high and low α-acids content without the use of analytical standards was established from a simple electrophoretic analysis.

Sub-minute determination of rifampicin and isoniazid in fixed dose combination tablets by capillary zone electrophoresis with ultraviolet absorption detection.

A validated sub minute capillary zone electrophoresis method with direct ultraviolet absorption detection for simultaneous determination of isoniazid and rifampicin in fixed-dose combination tablets was developed. Background electrolyte was defined based on the analytes effective mobility curve and it was composed by 20 mmol/L of sodium carbonate/sodium bicarbonate at pH 10.2. A careful validation procedure considering the main figures of merit was performed. Regression models were satisfactory for isoniazid and rifampicin, showing no lack of fit within 95% significance interval. Interday and intraday precision were evaluated in standard and sample and slight relative standard deviations were achieved for concentration, area, and migration time. Recovery values for accuracy in two levels were 99.97 and 90.08% for isoniazid and 95.45 and 95.12% for rifampicin. The limits of detection for isoniazid and rifampicin were 0.22 and 0.34 mg/L, respectively, and the limits of quantification were 0.74 and 1.13 mg/L, respectively. Method selectivity was verified by injecting diluent, background electrolyte, a standard mixture, and a sample, confirming no interferent peaks. The method proved to be simple, environmentally friendly, sensitive, and was successfully applied for simultaneous quantification of isoniazid and rifampicin in fixed-dose combination tablets.