NIR spectra of insulin solution monitored in the present study.

<p>(A) Raw NIR spectra data set. Two regions over 1300–1600 nm and 2050–2350 nm were focused on to evaluate changes with water and protein structures, respectively. (B) A magnified view at 1300–1600 nm. The direction of absorbance increment is indicated by an arrow. (C) Time-dependency of absorbance. Absorbance increment obtained by averaging absorbance over 1300–1600 nm (closed circles) or 2050–2350 nm (open circles) was plotted against time. The three phases, i.e., phases I (nucleation), II (elongation), and III (equilibrium), are represented.