The effectiveness of nitrogen-based surfactants in a wide range of industrial applications depends on active material being present in sufficient quantities in the correct phase of a two-phase liquid system; thus the partition coefficient of a surfactant can be an indication of its potential performance in application. Partition coeflicients have been measured between heptane and 0.1 (M) aqueous sodium hydroxide for a range of short to medium chain length amines and related compounds. The linear relationship between the logarithm of the partition coefficient and the alkyl chain length or degree of ethoxylation has been used to calculate experimentally inaccessible partition coefficients for surfactant-length compounds. The implications of how composition affects the partition of commercial products containing mixtures of components are discussed. A mines are weak bases and thus the degree to which they are protonated in aqueous solution depends on (\mathrm{pH}). Calculations have been carried out to predict the dependence of partition on aqueous phase (\mathrm{pH}) and the results have been compared with experimental values. Partition coefficients determined in the heptane/aqueous system have been compared with values obtained from literature in which octanol is the organic solvent and reasons suggested for the differences between the two sets of data. (1993 Academic Press, Inc.