The direct measurement of compounds encapsulated into liposomes without pretreatment allows verification of both the encapsulation efficiency and the release rate of liposomes in their original state. In the present study, the direct analysis of liposomes was conducted via resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). When analyte species (2-phenoxyethanol) encapsulated in liposomes were measured online, spike signals appeared in a time profile of the peak area for 2-phenoxyethanol, which suggested a dispersion of the compound in this sample.
View Article and Find Full Text PDFResonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) was used to study the characteristic signal behaviors obtained from two types of emulsions: water-in-oil (W/O) and oil-in-water (O/W). All emulsions were prepared using phase inversion emulsification, i.e.
View Article and Find Full Text PDFIn this study, we used a quantitative analytical method to indicate creaming behavior in an emulsion. An oil-in-water emulsion was directly measured by resonance-enhanced multiphoton ionization time-of-flight mass spectrometry, and the time profiles of the peak areas of an oil component, styrene, were obtained at heights of 1, 2, and 3 cm from the bottom of a sample that had a height of 4 cm. All time profiles roughly indicated that the signal intensity increased once, then decreased, and finally settled.
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