Fig. 2.

(a) Spectra of fermentation broth without POX (Broth, dotted line), fermentation broth spiked to a final POX concentration of 1 g L⁻¹ (Spiked 1, dash-dot line) and spiked to a final concentration of POX of 2 g L⁻¹ (Spiked 2, solid line). The spectral range in which POX-specific bands can be seen is indicted by the black box. (b) Difference spectrum of Spiked 1 (1 g L⁻¹ POX) and the Broth spectrum (solid line) and spectrum of 1 g L⁻¹ POX in 20 mM phosphate buffer (dashed line). The correlation between the spectra is very good, especially in the region between 1200 and 1400 cm⁻¹ (spectra are offset for clarity).