Partitioning refers to the distribution of a compound between
two immiscible phases and can explain the affinity of a compound
for an organic phase over its original aqueous phase (Palleros,
1995). The uptake of riboflavin into blank microbeads from an
external aqueous solution was examined as a process of partition
(Fig. 3). Fig. 3 shows a plot of the mass ratio ðMbead=MaqÞ versus
the volume ratio ðVbead=VaqÞ for riboflavin in microbeads, where
the mass ratio is the ratio of riboflavin in the microbead ðMbeadÞ
to the ratio of riboflavin in solution ðMaqÞ at equilibrium. The volume
ratio is the ratio of microbead volume ðVbeadÞ to the volume
of the riboflavin solution ðVaqÞ. Plotting the mass ratio against
the volume ratio relates the mass of riboflavin in the microbeads
to the volume of surrounding solution. The good fit of the data to
the linear model (R2 = 0.97) is consistent with the encapsulation
mechanism being governed by partition theory, in that there is a
proportional relationship between the volume of the microbead
phase and the mass of solute moving into that phase. The slope
of the line can then be used to calculate the equilibrium constant
(K) from Eq. (3).