A comparison of log Kow (n-octanol–water partition coefficient) values for non-ionic, anionic, cationic and amphoteric surfactants determined using predictions and experimental methods

Environmental Sciences Europe

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[1] 0000 0000 9450 4795, grid.423600.3, CEFIC, Av E Van Nieuwenhuyse 4, 1160, Brussels, Belgium;0000 0001 1551 0781, grid.3319.8, BASF SE, 67056, Ludwigshafen, Germany;0000 0001 2337 3756, grid.423893.7, Akzo Nobel NV, Velperweg 76, 6824 BM, Arnhem, The Netherlands;0000 0004 0513 2862, grid.474214.0, Salford City Council, Swinton, M27 5AW, Manchester, UK;0000 0004 0573 9904, grid.418010.c, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, 57392, Schmallenberg, Germany;0000 0004 0598 4264, grid.418707.d, Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, MK44 1LQ, Bedford, UK;0000 0004 0603 3866, grid.426005.5, Solvay, 20, rue Marcel Sembat, 69190, St Fons, France;0000 0004 1368 0092, grid.418758.7, Procter & Gamble, 11530 Reed Hartman Hwy, SWIC, 45241, Cincinnati, OH, USA;CVE Consultancy Limited, CH48 7EB, West Kirby, Merseyside, UK;Evonik Nutrition and Care GmbH, Goldschmidtstr. 100, 45127, Essen, Germany;Huntsman Europe, Everslaan 45, 3078, Everberg, Belgium;grid.425582.c, Procter & Gamble, Temselaan 100, 1853, Strombeek Bever, Belgium;grid.433370.0, Clariant Produkte (Deutschland) GmbH, 65926, Frankfurt/M, Germany;

关键词: Surfactants;    K;    Experimental methods;    Predictive (QSPR) models;   

DOI  :  10.1186/s12302-018-0176-7

来源: publisher

【 摘 要 】

BackgroundSurfactants are widely used across the globe both in industrial and consumer products. The n-octanol/water partition ratio or coefficient (log Kow) and n-octanol/water distribution coefficient (log D) are key parameters in environmental risk assessment of chemicals as they are often used to estimate the environmental fate and bioavailability and thus exposure and toxicity of a compound. Determining log Kow data for surfactants is a technical challenge due to their amphiphilic properties. Currently several existing experimental OECD methods (e.g. slow-stirring, HPLC, solubility ratio) and QSPR models are available for log Kow/D measurement or prediction. However, there are concerns that these methods have not been fully validated for surfactants and may not be applicable due to the specific phase behaviour of surfactants.ResultsThe current methods were evaluated for the four surfactant classes (non-ionic, anionic, cationic and amphoteric). The solubility ratio approach, based on comparative n-octanol and water solubility measurements, did not generate robust or accurate data. The HPLC method generates consistently higher log Kow values than the slow-stirring method for non-ionics, but this positive bias could be removed using reference surfactants with log Kow values determined using the slow-stirring method. The slow-stirring method is the most widely applicable experimental method for generating log Kow/D data for all the surface-active test compounds. Generally, QSPR-predicted log Kow/D values do not correlate well with experimental values, apart for the group of non-ionic surfactants. Relatively, large differences in predicted log Kow/D values were observed when comparing various QSPR models, which were most noticeable for the ionised surfactants.ConclusionsThe slow-stirring method is the most widely applicable experimental method for generating log Kow/D data for all the four surfactant classes. A weight of evidence approach is considered appropriate for non-ionic surfactants using experimental and model predications. However, it is more difficult to apply this approach to ionisable surfactants. Recommendations are made for the preferred existing QSPR predictive methods for determination of log Kow/D values for the surfactant classes. Investigation of newer alternative experimental log Kow methods as well as more biologically relevant and methodologically defensible alternative methods for describing partitioning of surfactants are recommended.

【 授权许可】

CC BY