posted on 2022-01-05, 00:13authored byTomonobu Sugiyama, Minori Minami, Tomohiro Uchimura
Herein, we propose
a method for evaluating the movement of a constituent
in a multiple emulsion while maintaining its original dispersed condition.
In this study, an oil-in-water-in-oil (O1/W/O2) emulsion was prepared using a two-step emulsification method with
styrene as an analyte species in the inner phase (O1).
The emulsion was measured using resonance-enhanced multiphoton ionization
time-of-flight mass spectrometry without pretreatment such as centrifugation.
From a series of obtained mass spectra, a time profile for the peak
areas arising from styrene was constructed. When the emulsion was
measured immediately following preparation, a time profile composed
of a base, positive, and negative signals confirmed the presence of
styrene in the O2, O1, and W phases, respectively.
Moreover, while a small amount of styrene was present in the inner
O1 phase, almost all of the styrene was found in the outer
O2 phase. Furthermore, the results of the obtained time
profile were converted into a box plot, and a method for the selection
of the base, positive, and negative signals was tentatively determined.
Then, the movement of styrene among the phases could be evaluated
using the time courses of these signals; the time constant of the
movement of styrene from an O1/W droplet to the O2 phase was calculated to be 0.8 h.