Fig. 4.

UV/visible spectra from the peaks at approximately 65 ml (a) and 37.5–40 ml (b) in Fig. 3(a). Based on the data presented by Chambers et al. (1996), the peak at 65 ml is the apo form of Ybt while the peak at 37.5–40 ml is ferrated Ybt. The identifying characteristics of the apo form are the presence of three distinct maxima at 210, 251 and 309 nm (a), while the ferrated form has four distinct maxima at 226, 256, 306 and 388 nm (b).