The
solvent systems used were as follows: an isocratic
elution of 20% CH3CN containing 0.05% TFA in water
for 80 min, a linear gradient elution using 20–90% of
CH3CN containing 0.05% TFA in water for 15 min, and
then an isocratic elution of 90% CH3CN containing
0.05% TFA in water for 50 min. OTPP were eluted at
between 130 and 140 min. The weight-average molecular
weight (Mw) and number-average molecular-weight
(Mn) values of OTPP were 2,017 and 903