Fig. 3. Spectra are shown for two identically prepared samples before and after (a) T₁ data acquisition in the NMR magnet (14 h at 32°C) and (b) incubation in an oven (17 h at 30°C). The difference spectra are the result of subtracting the respective before and after spectra from each other. Significant changes in the phosphonate region can be clearly seen (dotted lines). Apparent differences in the orthophosphate monoester region (*) are likely due to subtraction artifacts. Both samples are litter extracted with NaOH-EDTA.