CUTICULAR SORPTION AND DESORPTION OF A NONIONIC DIETHYLENE GLYCOL MONOOLEATE SURFACTANT

Sorption and desorption of 'Pegosperse' 100-0 (PEG 100-0; diethylene g lycol monooleate, containing 15% diester) surfactant by unaltered (CM) and dewaxed (DCM) adaxial cuticle membranes isolated from apple (Malu s pumila M.) leaves were studied. The aim of this study was to underst and interactions between surfactants and cuticles. Enzymatically isola ted cuticles were soaked in buffer or PEG 100-0 solution (pH 7.0), and the weight changes of cuticles were measured to determine the amount of surfactant sorbed or desorbed by the cuticles. For very low surfact ant concentrations, sorption was measured by changes in the surface te nsion of the solutions. PEG 100-0 sorption by both the CMs and the DCM s occurred mainly in the first three hours and was concentration-depen dent. The DCMs always sorbed more surfactant than the CMs. Desorption of PEG 100-0 from both CMs and DCMs was rapid in the first few hours a nd then decreased to a relatively low rate until the surfactant was to tally desorbed from the cuticles after about two months. The sorption and complete desorption of the surfactant by both CMs and DCMs show th at PEG 100-O interacts with both cutins and waxes of the cuticles and the interactions are reversible.