the measurement presented here are from equilibrium liquid samples in a vapor-tight stainless steel sample cell. high purity water produced by a Barnstead Nano Pure system:n-alkanes were purchased from sigma and fluma. the alkanes were purified by passing them several times through a column of basic alumina. the interfacial tension, measured with a wilhelmy plate, between these purified alkanes and water was constant to within(+,-0.1)dyn/cm an a function of time,where time is measured from the initial formation of the water-alkane interface. without this purification step,even the highest purity commercially available alkanes showed significant adsorption of impurities to the water-alkane interface as indicated by changes in the interfacial tension of up to 10 to 20 dyn/cm over a period of a few hours.