  Water in oil emulsions have a wide range of applications from chemical
technology to microfluidics, where the stability of water droplets is of
paramount importance. Here using an accessible and easily reproducible
experimental setup we describe and characterize the dissolution of water in
oil, which renders nanoliter-sized droplets unstable, resulting in their
shrinkage and disappearance in a time scale of hours. This process has
applicability in creating miniature reactors for crystallization. We test
multiple oils and their combinations with surfactants exhibiting widely
different rates of dissolution. We derived simple analytical equations to
determine the product of the diffusion coefficient and the relative saturation
density of water in oil from the measured dissolution data. By measuring the
moisture content of mineral and silicone oils with Karl Fischer titration
before and after saturating them with water, we calculated the diffusion
coefficient of water in these two oils
