Javier Domínguez-Alvarez

• University of Salamanca

In recent years the nutritional and bioactive properties of foods are being intensively investigated with a view to control, in addition to food quality, their possible influence on human health. Because of this, there is a growing demand for rapid, selective, sensitive, and validated methods for analysis and quantification. Bioactive plant compoun...

Benzimidazole derivatives are anthelmintic drugs that are widely used in the treatment of parasitic infections in animals destined for food production. In general, anthelmintic residues in foods do not pose any risk for human health, as long as the drugs are administered appropriately and at the recommended dose using the specified withdrawal times...

The present work describes a method for the simultaneous determination of unmodified nucleosides and nucleotide mono-, di- and tri-phosphates by capillary electrophoresis coupled to mass spectrometry (CE-MS). The use of hexafluoro-2-propanol (HFIP) in the separation medium, and as an additive to the sheath liquid of the electrospray interface (ESI)...

Nucleosides and nucleotides are intracellular compounds that are precursors of nucleic acids and which take part in various regulatory and metabolic functions. Although they can be synthesised endogenously, a dietary supplement is beneficial to the organism under certain conditions when the demand for these semi-essential nutrients is high. The ana...

In this work capillary electrophoresis-electrospray mass spectrometry (CE-ESI-MS) is proposed for the identification and simultaneous quantification of several ribonucleotide 5'-monophosphates in infant formula samples. The target compounds were adenosine 5'-monophosphate, cytidine 5'-monophosphate, guanosine 5'-monophosphate, uridine 5'-monophosph...

The application of programed nebulizing-gas pressure (PNP) has been previously described to be a simple strategy for the separation of anions by capillary electrophoresis-electrospray-mass spectrometry (CE-ESI-MS). The PNP mode provided high resolution and stable analyses and also had the advantage of allowing the use of capillaries wider than the...

Capillary zone electrophoresis coupled with electrospray ionization mass spectrometry (CZE-ESI-MS) has been applied for the first time for the separation and quantification of isoflavones in soy products. The proposed method was successfully applied to the determination of seven isoflavones, including aglycones and glucosides, in soy drink. The tar...

Here we have developed a method for the analysis of anionic compounds by capillary electrophoresis coupled to electrospray ionization-mass spectrometry (CE-ESI-MS). The strategy proposed is based on the application of programmed nebulizing gas pressure (PNP), which is applied during the different steps of analysis: sample injection, electrophoretic...

An analytical method based on CZE coupled to ESI-MS is proposed for the identification and simultaneous quantification of several endocrine-disrupting chemicals in honey. The target compounds were the chlorophenols: 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol, and bisphenol-A, 4-tert-butylphenol, and 4-tert-butylbenzoic acid. A...

In the present work we report a non-aqueous electrophoresis method (NACE) for the separation and determination of eight tricyclic antidepressants (TCAs) in human serum. Separation is carried out in 1 M acetic acid, 50 mM ammonium acetate and 10 mM SDS in ACN. Standards and samples were prepared in 0.8 M acetic acid in ACN and introduced by electrok...

In the present work we address the development of a simple and effective method for the determination of triazine herbicide residues in horticultural products by CE in nonaqueous media (NACE). Potato samples were selected as a representative matrix of such foods with a nonfatty content. Isolation of the analytes from the sample matrix was accomplis...

CZE was assayed for the separation of carbamate pesticides susceptible to protonation (Pirimicarb, Carbendazim). Different electrophoretic media with high organic contents were explored, adequate separation and resolution being achieved when a BGE based on ACN with acetic acid in the presence of SDS as an ionic additive was used. With a view to inc...

We have developed a method involving extraction with mixtures of solvents under pressure (pressurized liquid extraction (PLE)) for the determination of triazine herbicides in a series of samples from the food industry. The organic extracts obtained were subjected to a clean-up step with SPE, using Oasis MCX sorbents, after which they were analyzed...

We propose a procedure for estimating acid-base constants in organic solvents or mixture of solvents from the corresponding pK(a) values in aqueous medium and from certain properties of the organic solvents that characterize them. To accomplish this, we developed and validated a chemometric correlation for the calculation of the acid-base constants...

A method of capillary electrophoresis (CE) for the determination of triazine herbicides and some of their main metabolites in water samples has been developed. The proposed CE method includes an off-line solid-phase extraction (SPE) procedure with LiChrolut EN sorbent coupled to a non-aqueous capillary electrophoresis (NACE) separation with UV dete...

CE in nonaqueous media was used to study the migrating behavior of two weakly basic s-triazine pesticides and one of their metabolites. The target pesticides were selected to be representative for each of the two main groups: propazine and deethylatrazine for the chloro-s-triazines group and ametryn for the methylthio-s-triazines group. To elucidat...

A preconcentration study based on the cloud point phenomenon was carried out for a set of triazine herbicides, three of them chloro-substituted and three of them methylthio-substituted. Concentration factors and recoveries were calculated as function of the percentage of the non-ionic surfactant Triton X-114 employed. From these values, obtained fr...

Micellar electrokinetic capillary chromatography (MEKC) with diode array detection was used for the separation of 13 compounds (eight herbicides widely used in agriculture: metribuzin, lenacil, ethofumesate, atrazine, terbutryn, isoproturon, chlorotoluron and linuron, and five of their principal degradation products; namely, deethylatrazine, 2-hydr...

The separation and determination of a mixture of chloro- and methylthiotriazines in water samples by both micellar electrokinetic capillary chromatography (MEKC) and nonaqueous capillary zone electrophoresis (NA-CZE) were compared. The characteristics of both methods proved to be very similar in terms of separation efficiency and analysis times, bu...

Capillary zone electrophoresis (CZE) in an organic medium was used to analyse triazines at sub-ppb concentration levels in natural waters after a preconcentration step using conventional C18 cartridges and new Oasis HLB devices. With both sorbents, satisfactory results were obtained on analysing deionized water. However, on analysing natural waters...

Cloud point extraction was applied as a preconcentration step prior to capillary electrophoresis. The behavior of a surfactant-rich micellar phase injected into a capillary electrophoresis system was studied using different separation modes:  micellar electrokinetic capillary chromatography and capillary zone electrophoresis (CZE). A problem that a...

Capillary zone electrophoresis (CZE) in nonaqueous media and in the presence of ionic additives has been successfully applied to the determination of compounds that differ only slightly in their electrophoretic mobilities. Triazine herbicides of environmental interest were chosen as test compounds because they behave as very weak bases. CZE separat...