Resolved and unresolved questions of analysis of surfactants in the aquatic environment

214 references concerning the analysis of surfactants in the aquatic enviro nment have been reviewed. Methods for the analysis of anionic and cationic surfactants are critically discussed, but closest attention is paid to non- ionic surfactant, as this type of surfactant gives rise to the most serious unresolved questions of analysis. Typical levels of concentration of ionic and non-ionic surfactants in raw and treated sewage, surface water and riv er sediments are given. Recently developed tensammetric techniques, useful for the analysis of non-ionic surfactants and their metabolites, are broadl y described. The following unresolved questions related to anionic surfacta nts are emphasised: specific determination of different classes of anionic surfactants (alkyl sulphates, alkylether sulphates), analysis of metabolite s of anionic and non-ionic surfactants, and the problem of 'pseudosurfactan ts'. In the case of cationic surfactants, the question of inconclusive resu lts of measurements of aquatic environment samples is selected as the most serious problem. The need to develop analytical tools for the investigation of interactions between cationic and anionic surfactants in the aquatic en vironment is also emphasised. The following unresolved questions are distin guished for non-ionic surfactants: selection of method for determining the total concentration of non-ionic surfactants capable of approval in interla boratory tests, selection of the standard surfactant representative for the mixture of non-ionic surfactants in the aquatic environment, and the devel opment of methods for determining non-ionic surfactants having less than 5 oxyethylene subunits, as well as those having more than 30 subunits. The de velopment of methods for the specific determination of such classes of etho xylates as oxyethylated amines, oxyethylated fatty acids, as well as method s for the specific determination of newly introduced non-ethoxylate non-ion ic surfactants such as alkyl polyglucosides and metabolites of non-ionic su rfactants is suggested. Methods for the trace analysis of non-ionic surfact ants also require development as do methods suitable for controlling biodeg radation at a realistic level of concentration. The necessity for the futur e development of detectors for HPLC and FIA of oxyethylated alcohols and in the automation of the analysis of nonionic and cationic surfactants is emp hasised.