C. Shih et al., QUANTITATIVE-ANALYSIS OF ESTER LINKAGES IN POLY(DL-LACTIDE) AND POLY(DL-LACTIDE-CO-GLYCOLIDE), Journal of controlled release, 38(1), 1996, pp. 69-73
A quantitative analytical method for determination of intact ester lin
kages in biodegradable poly(DL-lactide) (PLA) and poly(DL-lactide-co-g
lycolide) (PLGA) has been developed. The polymer backbone ester bonds
were converted to amides by a facile reaction with n-butylamine under
ambient conditions. The resulting amides were analyzed by gas chromato
graphy. The amidation of both types of ester bonds was quantitative; r
eaction of the glycolate and lactate linkages was completed within 3 a
nd 8 h, respectively. The method was free from interferences by lactic
or glycolic acids and was tolerant of extraneous water. The values de
termined by this method were within 5% of those obtained by H-1-NMR. A
pplication to the study of the hydrolysis of poly(DL-lactide-co-glycol
ide) was demonstrated where the degradation profiles of the glycolide
and lactide linkages were simultaneously determined.