For this purpose the absorbance corresponding to
next bonds were measured: n(C-C) of backbone
corresponding to 970 cm1 (A970), n(C–O)d corresponding
to 1013 cm1 (A1013), ns(PO2) corresponding
to 1088 cm1 (A1088), and n as(PO2)
corresponding to 1230 cm1 (A1230). The ratio
A1088=A1230 was used as a separate variable
because of the sensitivity of this ratio to the changes
of the molecular structure.