Determination of the total content of calcium and magnesium and their bioavailability in ripened bee honeys

An analytical scheme for the fractionation and the determination of Ca and Mg in different bee honeys is presented. Using tandem column solid phase extraction based on a nonionic macroreticular adsorbing resin Amberlite XAD-16 and a gel-type strong cation exchange resin Dowex 50Wx8-200, three different groups of the Ca and Mg species were separated, including the hydrophobic, the cationic, and the residual species fractions. The concentrations of Ca and Mg were measured by means of flame atomic absorption spectrometry without any special chemical preparation of the analyzed samples. When regarding the total concentrations of Ca and Mg in the analyzed ripened floral and honeydew honeys, it was assessed that the most abundant group of the metal species was the cationic fraction, contributing for some honeys up to 96.3 and 97.0% of Ca and Mg, respectively. A relatively significant contribution of the hydrophobic fraction was also found, i.e., up to 20.1% for Ca and 23.0% for Mg.

Evaluation of the total content and the operationally defined species of copper in beers and wines

A two-column solid phase extraction was used to determine the operationally defined speciation of Cu in lager beers and red wines. Applying a nonionic macroreticular adsorbing resin Amberlite XAD-16 and a gel type strong cation exchange resin Dowex 50Wx8-200, three different groupings of the chemical forms of Cu, including the hydrophobic, the cationic, and the residual species fractions, were separated and determined. The total content of Cu in the analyzed samples and its concentrations in the distinguished fractions were measured using flame atomic absorption spectrometry without any special preparation of the sample solutions. It was found that the residual species (72-82% of the total content), being polar and noncationic forms of Cu, are the most abundant fraction of Cu in the analyzed beers. In the case of wines, the fraction of the hydrophobic species was established to have the highest share in the total Cu content, that is, 27-77%. This fraction was presumed to contain relatively strong complexes of Cu with various flavonoids and other polyphenols.