Binding of the Trace Elements: Cu(II) and Fe(III) to the Native and Modified Nutritive Potato Starches Studied by EPR

H. Śmigielskaa, G. Lewandowiczb, J. Goslarc and S.K. Hoffmannc aPoznań University of Economics, Faculty of Commodity Science, Al. Niepodległości 10, 60-967 Poznań, Poland bA. Cieszkowski Agricultural University, Dept. of Biotechnology and Food Microbiology, Wojska Polskiego 48, 60-627 Poznań, Poland cInstitute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland

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Received: 24 04 2005;

The Cu(II) and Fe(III) ions have been adsorbed by four potato starches of different degrees of oxidation (different numbers of COOH groups replacing host CH2OH groups): native (no oxidized), white (pudding) with oxidation degree of 0.04%, gelating (0.1%), and LUBOX starch (0.5%). Concentration of the ions in starches was determined from atomic absorption and EPR spectrum intensity. For small concentration of the adsorbed ions (below 4 mg/g) nearly all ions are adsorbed from the solution. EPR shows that adsorbed copper(II) ions are chemically bonded to the starch molecules (preferably) at COOH sites and uniformly dispersed in the starch structure. The complexes are typical of octahedral or square-quadratic coordination with spin-Hamiltonian parameters gǁ=2.373, g⊥= 2.080, Aǁ=12.1 mT, A⊥=1.0 mT. For higher concentrations the Cu(II) displays a tendency to clustering. Iron(III) ions are introduced into starch in a form of clusters mainly, even for the smallest concentration. The highest concentrations of both Cu(II) and Fe(III) were observed in LUBOX starch having the highest degree of oxidation.

DOI: 10.12693/APhysPolA.108.303 PACS numbers:76.30.-v, 87.15.-v