Time-Profile Measurement of an Emulsion Using Multiphoton Ionization Time-of-Flight Mass Spectrometry in Combination with a Microscope

Abstract

Multiphoton ionization time-of-flight mass spectrometry was applied to the measurement of an oil-in-water emulsion that contained toluene as a dispersed phase. Before the measurement, the sample was sufficiently creamed, and then stirred for a short period of time for dispersion. As a result, several intense spikes appeared on the time profile constructed from the peak area for toluene. In the present study, an optical microscope was used to observe the capillary column for sample introduction, and small toluene droplets along with their aggregates were found in the images of the emulsion flowing through the capillary. The aggregates produced intense spikes comprised of multiple plots, which could be easily marked by applying a moving median filter. In the present study, droplets with minimum diameters as small as 2.9 μm, which corresponds to 13 fL, could be calculated as detectable spikes.

A Quantitative Analysis of an Oil Component in an Emulsion by Multiphoton Ionization Mass Spectrometry

“…3 μm in the case of a toluene O/W emulsion. 17 With this technique, we demonstrated the possibility of evaluating the creaming of emulsions from the time course of a peak area. 15 In the present study, we demonstrated the possibility of a quantitative analysis of an oil component in an emulsion via MPI-TOFM, which has not been achieved.…”

“…3 μm could be detected as a spike in the case of a toluene O/W emulsion. 17 By carefully checking the time profiles for styrene, the signal intensity seemed to have decreased sometimes before the occurrence of the intense spikes when measuring emulsions with higher concentrations of styrene. One possible reason is the generation of aggregates of styrene droplets.…”

“…Recently, we reported on the results of the online monitoring of emulsions with no pretreatment using multiphoton ionization time-of-flight mass spectrometry (MPI-TOFMS). [15][16][17][18] MPI-TOFMS has several advantages, such as spectroscopic selectivity and robustness, [19][20][21][22][23][24][25] and several applications have been reported such as online monitoring of the environment.…”

Online Monitoring of a Styrene Monomer and a Dimer in an Emulsion via Laser Ionization Time-of-Flight Mass Spectrometry

“…17,18 These spikes indicate the existence of a highly concentrated oil component, which amounts to only a small oil droplet. 19 We also applied this method to the direct measurement of analytes in a water-in-oilin-water (W/O/W) multiple emulsion. 20 LI-TOFMS can produce information about the local microenvironment of an emulsion, and, therefore, we theorized that this technique could be applied to the direct detection of monomers and oligomers generated during emulsion polymerization, which is a polymerization technique.…”

Application of Laser Ionization Time-of-Flight Mass Spectrometry for the Direct Measurement of a Silane Coupling Agent in Slurries

“…In addition, we also applied LI-TOFMS to the measurement of liquid samples, 34,35 including emulsions. [36][37][38][39] In the present study, we treated TiO2 nanoparticles with PTES and prepared slurry samples where PTES either remained or was removed by washing. Then, a direct mass analysis of the slurries was performed by LI-TOFMS, and we confirmed whether the remaining PTES could be detected.…”