EPR spectra of copper(II) compounds in different pH environments. The copper (Cu2+) solutions were 5 mM in de-ionized water. The pH was adjusted with HCl or NaOH as appropriate. At pH 1, both forms of copper yield a single-line spectrum, g = 2.19, ΔHpp ≈ 140 G. At pH 7, Cu(II)AAC has a g-value of 2.12 with a copper hyperfine splitting of 63 G.
Rabovsky et al. Nutrition Journal 2010 9:61 doi:10.1186/1475-2891-9-61