Figure 1. Effect on the solvent of hepcidin-25⁺⁴⁰ on hepcidin-25 linearity and value assignment.

Hepcidin-25⁺⁴⁰ was dissolved in 20% acetonitril (acn), 5% phosphoric acid or water and used as internal standards in blank serum samples containing end concentrations of 0, 0.5,1, 2, 3, 5, 7.5, 10, 15, 20 and 40 nM synthetic hepcidin-25 purchased from Peptides International. Linearity of measured hepcidin-25 was determined by the formulas: Y = 1.822X+0.097 (5% phosphoric acid); Y = 1.119X+0.494 (water); Y = 0.964X+0.069 (20% acn).