Abstract
Green vegetables contain relatively high amounts of calcium. To analyze the chemical species of calcium in spinach (Spinacia oleracea), Malabar spinach (Basella alba), and Komatsuna (Brassica rapa Var. perviridis), the calcium K-edge X-ray absorption near edge structures (XANES) were measured using the dried powder samples of these vegetables. The XANES of calcium carbonate, calcium lactate, ascorbic acid calcium, and calcium oxalate were used as reference spectra for comparison. The XANES of spinach and Malabar spinach were consistent with the shapes of calcium oxalate. Komatsuna was similar to the shapes of ascorbic acid calcium and calcium lactate. The electrochemical behavior of these vegetables was also examined. The oxidation peak current, which can be attributed to calcium extraction, was the largest in Komatsuna among them. The calcium K-edge XANES of Malabar spinach treated with different potentials was investigated to analyze the chemical state change of calcium species induced by electrochemical reactions, but it did not show electrochemical potential dependency.
