The quality parameters of the resolution with the 1
H-NMR data
show that the model contains a significant lack of fit (errors and
variance explained) and provides low spectral correlation values.
The information obtained from Fig. 2b should be interpreted with
this in mind. It is surprising that that the concentration of Acid Red
97 seems to increase during the first minutes and then decreases.
Also, the first intermediate does not appear until the 12th minute
of degradation. One explanation for this is that the resolution
confuses the different compounds, especially the spectrum of Acid
Red 97 and the spectrum of an initial intermediate. In the later
stages of the process, new species (or new situations that keep
changing) appear. A comparison of the results of the two techniques
shows that when the data are more complex it is more
difficult to obtain a good model fit. The use of 1
H-NMR enables
qualitative information to be obtained about the intermediates (up
to four can be observed) but the concentration profiles are not in
agreement with the previous results and the quality parameters
obtained are not satisfactory either.