Characterisation of the water-isopropyl myristate system

Partition coefficients for compounds (solutes) from water to isopropyl myristate, IPM, have been obtained from the literature, either as directly determined partition coefficients or from solubilities in water and in IPM. The general solvation equation of Abraham has been applied to 141 such partition coefficients, as log Pipm, and it is shown that the main solute factors that influence partition are dipolarity/polarisability, hydrogen bond acidity and hydrogen bond basicity that reduce partition, and volume that increases partition. These factors are quantitatively very similar to those that influence partition in the water to olive oil system, and indicate that IPM has the expected behaviour of a long chain, hydrophobic ester. It is shown that the water to IPM system is a poor model for partition between water and human stratum corneum and for permeation from water through human skin.