Simultaneous determination of main phenolic acids and flavonoids in tomato by micellar electrokinetic capillary electrophoresis
[EN] A methodology for the determination of tomato phenolic acids and flavonoids has been developed combining MEKC and DAD detection. The influence on polyphenol separation of pH and background electrolyte, BGE (borax, acetonitrile, methanol and SDS concentrations), was studied and optimized using response surface methodology and weighted desirability function. Separation of polyphenols was achieved within 20 min at 15 degrees C using 11.3 mM borax and 11.2 mM SDS adjusted to pH 8.5 as BGE. Validation was performed using standards and tomato extracts. Recoveries ranged from 77 to 106%. Acceptable repeatabilities were obtained for peak area (% RSD <3.1% and <3.7%) and migration times (% RSD …
Fast simultaneous determination of prominent polyphenols in vegetables and fruits by reversed phase liquid chromatography using a fused-core column
A reversed-phase high-performance liquid chromatography method with photodiode array detection has been developed enabling the joint determination of 17 prominent flavonoids and phenolic acids in vegetables and fruits. A multi-segmented gradient program using a fused-core column for the separation of several phenolic classes (phenolic acids and flavonoids) has been optimised. The influence of extraction conditions (sample freeze-drying, ultrasound extraction, solvent composition and extraction time) has been also optimised using response surface methodology with tomato samples as a model. Complete recoveries (76-108%) were obtained for the phenolic compounds present in tomato. The developed…
High efficiency joint CZE determination of sugars and acids in vegetables and fruits
In this work, an improved CE method for the medium-throughput determination of main organic acids (oxalate, malate, citrate), the amino acid glutamate and the sugars fructose, glucose and sucrose in several food matrices is described. These compounds have been identified as key components in the taste intensity of fruit and vegetable crops. Using a running buffer with 20 mM 2,6-pyridine dicarboxylic acid pH 12.1 and 0.1% hexadimethrine bromide, replacing it every 5 h to avoid pH decrease, and optimizing capillary conditioning between runs with 58 mM SDS during 2 min at 20 psi, it is possible to effectively quantify these compounds while increasing medium throughput repeatability. This proce…