The retention behavior of the reversed-phase was evaluated under 100% aqueo
us conditions. It is commonly said that reversed-phases, such as ODS (C-18)
and C-8, show a decrease in the retention time under 100% aqueous conditio
ns. The mechanism of the decrease in retention was found to be that the 100
% aqueous mobile phase was pulled out of the pore of the packing materials,
so that the stationary phase in contact with the mobile phase decreased. S
ome parameters, such as the pore size, length of the alkyl group of the sta
tionary phase, temperature and buffer in the mobile phase, were shown to in
fluence the decrease in retention. The C-30 phase didn't show any decrease
of retention. Furthermore, ODS, which had a larger pore, didn't show any de
crease in the retention time, but showed high reproducibility in retention.
In contrast, TMS (C-1), which had a smaller pore, showed a decrease of ret
ention, although it was known that TMS, which had 10 nm of a pore, didn't s
how a decrease in retention. The reversed-phase could be used under 100% aq
ueous conditions, and showed high reproducibility in retention when it was
filled with some terms.