Dirt and Grime in Bathrooms: Their Chemical Composition and the Origin of the Triacylglycerols Contained Therein

Abstract

Bathrooms provide environments that encourage the formation of biofilms and mold on the hard surfaces of bathtubs and tile walls. To prevent such microbe-produced grime from spreading, methods such as bleaching and scrubbing may be commonly employed. The removal of dirt before the mold can grow is much more important, however, and therefore clarification of the composition and the accumulation mechanism of dirt and grime is needed. The grime collected from the shower walls of home bathrooms in our previous study consisted mainly of calcium soap, surfactants, fatty acids, and triacylglycerols. The triacylglycerols were suggested as playing an important role in the accumulation of grime, and in the present study we focused on their detailed composition and origin. A non-aqueous reverse-phase HPLC-ESI-MS/MS enabled us to characterize the small amount of triacylglycerols, but their MS/MS spectra were complicated by the presence of a number of product ions. Furthermore, there were no characteristic ions that allowed us to identify the triacylglycerols. Therefore, we adopted a new methodology in which only two ESI-MS/MS spectra corresponding to two m/z ranges in MS spectra (m/z 800–900 and 850–950) were acquired instead of a number of MS/MS spectra corresponding to each MS signal. This made it possible to estimate the origin of triacylglycerols by comparing the spectral patterns of the grime with those of the standard materials, with the desired convenience and quickness. The origin of the triacylglycerols should be closely related to the accumulation mechanism, though the triacylglycerols in the grime examined in the present study came mostly from human sebum instead of bath products and other sources.