María de los Ángeles Fernández

Olive Oil by Capillary Electrophoresis: Characterization and Genuineness

Olive oil, obtained from Olea europaea L. (Oleaceae) fruits, is an important ingredient in the Mediterranean diet. The purpose of this paper is to review and evaluate olive oil analysis using capillary electrophoresis (CE). This review covers a selection of the literature published on this topic over the past decade. The current state of the art of the topic is evaluated, with special emphasis on separation conditions, analysis purpose, and analytes investigated. CE has been used to characterize or to carry out authenticity studies. Particular attention has been focused on the botanical origin because high-quality monovarietal olive oils have been recently introduced on the markets and their quality control requires the development of new and powerful analytical tools as well as new regulations to avoid fraud. CE represents a good compromise between sample throughput, sample volume, satisfactory characterization, and sustainability for the analysis of target compounds present in olive oils.

High-throughput determination of phenolic compounds in virgin olive oil using dispersive liquid-liquid microextraction-CZE microextraction-capillary zone electrophoresis

This article reports a simple methodology using dispersive liquid–liquid microextraction combined with CZE. It has been applied for the simultaneous determination of phenolic compounds such as caffeic, gallic, vanillic, syringic, cinnamic, p‐coumaric acids and oleuropein, apigenin, luteolin, 3‐hydroxytyrosol, and tyrosol, in virgin olive oil (VOO). The optimized extraction conditions for 20 g of VOO were: extractant solvent: 400 μL boric acid 30 mM at pH 9.5; dispersive solvent: 300 μL carbon tetrachloride; vortex: 8 min; centrifugation: 3 min. The composition of the BGE was optimized resulting in the selection of a solution made of 30 mM boric acid at pH 9.5. As a strategy for on‐line preconcentration a stacking step was applied, injecting a plug of water before sample injection. The short extraction time, centrifugation and electrophoretic steps allow the selective determination of phenolic compounds in VOO with satisfactory LODs (0.004–0.251 mg/kg), recoveries (89.4–101.0%), and RSD (less than 7.44% in peak area and less than 0.69% in migration time), compatible with the concentration levels present in the samples.

High-throughput determination of phenolic compounds in virgin olive oil using dispersive liquid-liquid microextraction- capillary zone electrophoresis.

This article reports a simple methodology using dispersive liquid–liquid microextraction combined with CZE. It has been applied for the simultaneous determination of phenolic compounds such as caffeic, gallic, vanillic, syringic, cinnamic, p‐coumaric acids and oleuropein, apigenin, luteolin, 3‐hydroxytyrosol, and tyrosol, in virgin olive oil (VOO). The optimized extraction conditions for 20 g of VOO were: extractant solvent: 400 μL boric acid 30 mM at pH 9.5; dispersive solvent: 300 μL carbon tetrachloride; vortex: 8 min; centrifugation: 3 min. The composition of the BGE was optimized resulting in the selection of a solution made of 30 mM boric acid at pH 9.5. As a strategy for on‐line preconcentration a stacking step was applied, injecting a plug of water before sample injection. The short extraction time, centrifugation and electrophoretic steps allow the selective determination of phenolic compounds in VOO with satisfactory LODs (0.004–0.251 mg/kg), recoveries (89.4–101.0%), and RSD (less than 7.44% in peak area and less than 0.69% in migration time), compatible with the concentration levels present in the samples.

Novel approaches mediated by tailor-made green solvents for the extraction of phenolic compounds from agro-food industrial by-products

An environmentally friendly method for the phenolic compound extraction from agro-food industrial by-products was developed in order to contribute with their sustainable valorization. A Natural Deep Eutectic Solvent was chemometrically-designed for the first time and compared with traditional solvents in terms of analyte stabilization. The combination of lactic acid, glucose and 15% water (LGH-15) was selected as optimal. A high-efficiency ultrasound-assisted extraction mediated by LGH-15 prior to HPLC-DAD allows the determination of 14 phenols in onion, olive, tomato and pear industrial by-products. NADES synthesis as well as the extraction procedures were optimized by Response Surface Methodology. Thus, phenolic determination in these complex samples was achieved by a simple, non-expensive, eco-friendly and robust system. The application to different matrices demonstrated the versatility of the proposed method. NADES opens interesting perspectives for their potential use as vehicles of bioactive compounds as food additives or pharmaceuticals.

Natural deep eutectic solvents-mediated extractions: The way forward for sustainable analytical developments

The concept of sustainable development has impacted in analytical chemistry changing the way of thinking processes and methods. It is important for analytical chemists to consider how sample preparation can integrate the basic concepts of Green Chemistry. In this sense, the replacement of traditional organic solvents is of utmost importance. Natural Deep Eutectic Solvents (NADES) have come to light as a green alternative. In the last few years, a growing number of contributions have applied these natural solvents proving their efficiency in terms of extraction ability, analyte stabilization capacity and detection compatibility. However, the arising question that has to be answered is: the use of NADES is enough to green an extraction process? This review presents an overview of knowledge regarding sustainability of NADES-based extraction procedures, focused on reported literature within the timeframe spanning from 2011 up to date. The contributions were analyzed from a green perspective in terms of energy, time, sample and solvent consumption. Moreover, we include a critical analysis to clarify whether the use of NADES as extraction media is enough for greening an analytical methodology; strategies to make them even greener are also presented. Finally, recent trends and future perspectives on how NADES-based extraction approaches in combination with computational methodologies can contribute are discussed.