Antonio Sanchez-Perez

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A rapid analytical method including pressurized liquid extraction (PLE) and liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) has been developed for the determination of tocopherols and tocotrienols in cereals. The pressurized liquid extraction parameters were optimized in order to maximize the extraction efficiency. The use of(More)
A rapid and automated method for the analysis of alpha-, gamma- and delta-tocopherols in vegetable oils is reported. Continuous extraction of vitamin E isomers from oil samples dissolved in Triton X-114 in the presence of methanol-hexane is achieved and coupled on-line with the chromatographic system. Using an acetic acid/sodium acetate buffer in a(More)
A method is described for the determination of vitamin E isomers [alpha-, (beta+gamma)- and delta-tocopherols] in seeds and nuts by reversed-phase HPLC with coulometric detection. Three methods of sample treatment were compared. The first method included alkaline hydrolysis, extraction of analytes from unsaponifiable and injection into the chromatographic(More)
A comparative study of different surfactants, such as sodium dodecyl sulfate and bis(2-ethylhexyl) sodium sulfosuccinate (AOT), as pseudostationary phases was conducted in order to find the best conditions for the separation of the water- and fat-soluble vitamins by electrokinetic capillary chromatography. Separation was accomplished with AOT in a(More)
A method is described which uses the direct current (dc) polarographic behavior of cimetidine in a strong acid solution to determine this compound. The diffusional characteristics of the reduction wave of cimetidine in 1M HCl (about -0.8 V vs SCE) are shown, and their analytical usefulness was studied. This polarographic method was used to determine(More)
Pressurized liquid extraction (PLE) was used to isolate tocopherols from seeds and nuts. Very clean extracts were obtained, which were injected directly into the chromatographic system. This enables rapid and simple control in food analysis. The PLE extraction temperature was set at 50 degrees C, with two cycles of extraction, a static time of 5 min, and(More)
Capillary electrokinetic chromatography is suitable for the separation of mixtures of uncharged and charged solutes. In the present work the behavior of six synthetic food antioxidants--2[3]-tert.-butyl-4-hydroxyanisole, 2,6-di-tert.-butyl-p-cresol, tercbutylhydroquinone, 3,4,5-trihydroxybenzoic acid propyl ester, 3,4,5-trihydroxybenzoic acid octyl ester(More)
We developed an on-line system for the determination of liposoluble vitamins A, D3 and E in milk, both liquid and in powder form, using an automated sample treatment system coupled to chromatographic determination. For this, C18 cartridges were used because of the strong capacity of this material for the extraction and preconcentration of such vitamins, its(More)
A microemulsion electrokinetic chromatographic method was used to separate fat-soluble vitamins. The separation of retinol, cholecalciferol, and delta- and alpha-tocopherol was performed using a microemulsion containing 0.75% (v/v) n-heptane, 30 mM bis(2-ethylhexyl)sodium sulfosuccinate (AOT), 5% (v/v) 1-butanol, 15% (v/v) 1-propanol and 15% (v/v) methanol(More)
PURPOSE To evaluate the ability of Swept-source optical coherence tomography (SS-OCT) in detecting early endothelial graft detachment after Descemet membrane endothelial keratoplasty (DMEK) and to determine the possible causes of graft detachment using 2 different protocols for anterior segment (AS) imaging. METHODS Eight eyes from 8 consecutive DMEK(More)