Julie Le Grandois has completed her PhD in Analytical Chemistry in 2009 from University of Strasbourg (France). She is now Research Scientist in charge of the development of analytical methods at Aérial. She has published 11 papers in peer-reviewed journals.
Vitamins are essential for health but most of them are not synthesized by humans. Thus, vitamins have to be introduced through diet. Vitamins are an added value for food products. Their labeling requires identification and quantification. For that purpose, HPLC with UV or fluorimetric detections has been intensively used in the last years. These methods usually require specific chromatographic conditions for each vitamin, which is time consuming and expensive. Despite the democratization of analytical approaches such as mass spectrometry, the simultaneous determination of B-group vitamins remains challenging due to several reasons: i) their different structures and chemical properties; ii) their low stability; iii) their presence at trace levels in foods; iv) the complexity of food matrices. These features make it difficult to develop a single method for the simultaneous extraction, separation and quantification of B vitamins in foods. This work aims at combining a single enzymatic extraction step, with a single chromatographic run using ESI-MS² (MRM mode) to evaluate B vitamin content in foodstuffs. The design of experiments was used to determine the optimal pH and temperature conditions for the simultaneous extraction of B1, B2, B3 (nicotinic acid, nicotinamide), B5 (pantothenic acid), B6 (pyridoxine, pyridoxal, pyridoxamine) and B8 (biotin, biocytin) from food matrices. The efficiency of the procedure was investigated on four matrices (liver, yeast, powder milk, peas) and results were compared to the individual protocols. Results were conclusive and prefigured a good chance to develop an efficient mutivitaminic protocol.
Julie Le Grandois has completed her PhD in Analytical Chemistry in 2009 from University of Strasbourg (France). She is now Research Scientist in charge of the development of analytical methods at Aérial. She has published 11 papers in peer-review journals.
Since several years, antioxidant compounds are of great interest due to their implication in protection against radicals. Several studies have tried to understand which kinds of interactions occur in complex mixtures or extracts, since a potent regeneration of an antioxidant by another one can increase or decrease the activity of a mixture of antioxidants. In this study, individual TEAC (Trolox Equivalent Antioxidant Capacity) values of pure lipophilic compounds were first determined using a microplate assay and an online LC-AOx method, with post-column reaction. Then, TEAC values of lipophilic extracts from Solanum lycopersicum L. were also determined using both methods. Differences were observed and significant interactions were suspected. To evaluate these interactions, mixtures of lipophilic compounds were prepared in variable proportions. TEAC value (n=3) of each mixture was determined using the microplate TEAC assay. Interaction effects were calculated and additive, antagonist or synergic effects were observed. Results showed HPLC-ABTS provides individual TEAC values without interactions but helps in the identification of compounds involved in antioxidant capacity, whereas microplate assay only provides TEAC values of mixtures including interactions.