M.A. Lage-Yusty

HPLC analysis of organic acids using a novel stationary phase.

In the present work, a high performance liquid chromatographic method with UV detection for the separation of six organic acids including, tartaric, malic, acetic, lactic, citric and succinic is described. The separation was performed on a novel stationary phase TEKNOKROMA, Tr-010065 Mediterranea sea(18) (15 cm x 0.4 cm, i.d. 3 microm) and using water with a 0.1% (v/v) of formic acid as mobile phase. The advantages of this packing over a conventional octadecylsilane (ODS2) column are reported. The method was validated with respect to linearity, limits of detection and repeatabilities within day and between days and satisfactory results were obtained. The proposed method was applied for the determination of these compounds in commercially available white wines. The samples were injected directly without previous treatment. LC-MS was used as a confirmatory technique.

Changes in bioactive compounds content and antioxidant activity of seaweed after cooking processing

Wakame and Kombu seaweed, both fresh and reconstituted for consumption, were analyzed by HPLC for the determination of the content of ascorbic acid, vitamin E, β-carotene, lutein, fucoxanthin, chlorophyll a and pheophytin a; total polyphenol was done by Folin–Ciocalteau method and antioxidant activity by the DPPH test. Different behaviors have been observed on the contents of the bioactive compounds analyzed. Significant changes on ascorbic acid, β-carotene, lutein, fucoxanthin, chlorophyll a, pheophytin a, vitamin E, total polyphenols and antioxidant activity have been observed after the reconstitution of Wakame, whereas Kombu showed no significative variation of fucoxanthin, Vitamin E, total polyphenols and antioxidant activity. A high correlation between antioxidant activity and the above compounds was observed.

Comparison of methods for analysis of resveratrol in dietary vegetable supplements

Resveratrol is a stilbene, which is one of a group of polyphenols in many plant foods. Interest in this substance lies in its potential health benefits. This study aimed to compare two different methods, chromatographic and constant-wavelength synchronous spectrofluorimetry, an alternative technique to determine the amount of resveratrol dietary supplements, as a model for more complex foods. High-performance liquid chromatography-photodyode array detector-mass spectrometry/mass spectrometry was used to confirm the results. The results obtained showed that both methods were valid for the determination of resveratrol in dietary supplements. HPLC with fluorescence and variable wavelength detectors offered better linearity and sensitivity, and would be more suitable for the determination of several stilbenes in complex samples. On the other hand, constant-wavelength synchronous spectrofluorimetry is a sensitive, rapid and inexpensive method that could be used for quick and precise determination when samples are expected to contain only one stilbene.

Liquid Chromatographic Determination of Malvidin-3-O-Glucoside and Malvidin 3, 5-O-Diglucoside in Wine Samples by Direct Injection~!2008-04-11~!2008-05-06~!2008-06-12~!

A method for the determination of malvidin 3-O-glucoside (Oenin), and malvidin 3, 5-O-diglucoside (Malvin) in wines by on line HPLC coupled with UV, and fluorescence detectors is described. With the proposed method the samples were analysed by direct injection without a previous treatment. For method validation, satisfactory recoveries (> 95%) and suitable repeatabilities (within day: R.S.D. (n=6=) < 3%, and between days; R.S.D. (n=6=) < 3%) were achieved. The method was applied to the analysis of commercially available red wines.

Determination of phycobiliproteins by constant-wavelength synchronous spectrofluorimetry method in red algae

Phycobiliproteins are pigment–protein complexes, brilliant-colored and water soluble, existing in cyanobacteria and red algae. They have a great interest in food technology, food supplements, and pharmaceutical applications. Therefore it is important to have a fast, easy, and reliable method to determine the content of phycoerythrin (PE), phycocyanin (PC), and allophycocyanin (APC) in red algae. The samples are ground, extracted in phosphate buffer (pH 6.8), centrifuged, and the fluorescence scan of the supernatant is recorded. Optimum excitation-emission wavelength intervals (Δλ) for synchronous spectrofluorimetric analysis of the three phycobiliproteins were 10 nm for PE (LD = 10.9 × 10−3 mg/l) and APC (LD = 0.5 mg/l) and 40 nm for PC (LD = 0.77 mg/l). Algae analyzed contain PC and PE.

Comparison of two stationary phases for the separation of five selected polyphenols.

In this study, a conventional TEKNOKROMA, Tr-015605 TRACER EXTRASIL ODS2 (25 cm x 0.4 cm, i.d. 5 microm) column and a new stationary phase TEKNOKROMA, Tr-010065 Mediterranea sea(18) (15 cm x 0.4 cm, i.d. 3 microm) were compared for the separation of five phenolic compounds. Sensitivity, performance characteristics, analysis time and method validation were reported for both columns. A better sensitivity and performance were achieved with the novel chromatographic support. In addition the total analysis time was significantly reduced. The method was applied to the determination of the selected polyphenols in commercial available white wines. LC-MS was used as a confirmatory technique.

Occurrence and exposure of 3-monochloropropanediol diesters in edible oils and oil-based foodstuffs from the Spanish market

During the industrial refining process of edible oils and the manufacture of oil-based foodstuff, contaminants such as 3-monochloropropanediol (3-MCPD) fatty acid diesters can be produced. One hundred samples of different edible oils and related fatty food purchased from local Spanish markets were analyzed to evaluate the occurrence of these contaminants. Data of seven 3-MCPD diesters together with corresponding total 3-MCPD equivalents are presented. The procedure is based on a modified QuEChERS protocol followed by LC-MS/MS analysis. Extra virgin olive oil (EVOO) and unrefined oils did not contain detectable levels of the target analytes. The highest levels of 3-MCPD diesters were found in palm oils, for 1,2-Dilinoleoyl-3-chloropropanediol (LILI) and 1-2-Bispalmitoyl-3-chloropropanediol (PAPA) with concentrations close to 10 mg kg-1 and in the lipid fraction of margarines (8.09, 3.77 and 3.72 mg kg-1 for LILI, PAPA and 1-Oleoyl-2-linoleoyl-3-chloropropanediol (OLLI), respectively).