The equilibrium release values (Rmax) for tryptophan, riboflavin,
dipeptide and pentapeptide for the range of volume ratios studied
(0.13–0.6) are shown in Fig. 3. Partition theory can be used to
relate the affinity of compounds to the microbead or the release
medium. This theory (as described in Section 2.5) was applied to
the Rmax values of each of the compounds from the microbeads.
Tryptophan had the highest Rmax values of the four compounds
with 89 ± 1.5% released at a volume ratio of 0.13. However, this
value decreased with increasing volume ratio, with 57 ± 3%
released at a volume ratio of 0.6. A similar trend occurred for
riboflavin and the dipeptide with Rmax values decreasing with
increasing volume ratio, resulting in Rmax values of 41 ± 2.8% and
45 ± 3.6%, respectively at a volume ratio of 0.6. The pentapeptide
had significantly lower levels of release at equilibrium with Rmax
values ranging from 7.1 ± 0.3% to 3.1 ± 0.2% at volume ratios of
0.13 and 0.6, respectively.