Abstract

CATARINO, S.; TRANCOSO, I.M.; SOUSA, R. Bruno de  and  CURVELO-GARCIA, A.S.. Grape must mineralization by high pressure microwave digestion for trace element analysis: development of a procedure. Ciência Téc. Vitiv. [online]. 2010, vol.25, n.2, pp.87-93. ISSN 0254-0223.

The present work describes the development and validation of a high pressure microwave-assisted mineralization procedure for the determination of metals in grape must by spectrometric techniques. Metals of special oenological and food safety importance (Al, Co, Cu, Cd, Pb) were used as model elements to achieve the optimum working conditions. The study was conducted by monitoring their concentration in experimental samples by ETAAS. Different combinations of HNO₃ and H₂O₂ were tested and an optimal volume of 1 mL of each reagent, added to 2 mL of sample, was selected for further studies.  In comparison with experimental conditions described in literature for the mineralization of grape must and wine by HPMW, the proposed procedure requires very low reagent consumption. Time and temperature were regarded as factors in the optimization study of microwave oven program, resulting in 72 minutes of extension including ventilation. The procedure trueness and precision were evaluated using grape must and wine samples. For each element three different levels of addition were performed. The recovery range was from 94% (Co) to 113% (Pb) in grape must and from 96% (Cu) to 128% (Al) in wine. Relative standard deviations ranged from 1% (Cd) to 11% (Al) in grape must and from 2% (Cd, Pb) to 9% (Co) in wine (n = 10). The proposed procedure is suitable for grape must and wine mineralization with a view to trace element analysis.

Keywords : grape must; wine; mineralization; high pressure microwave digestion (HPMW); trace element analysis.

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