RP-18 TLC retention data and calculated physico-chemical parameters as predictors of soil-water partition and bioconcentration of organic sunscreens

Abstract

RP-18 TLC chromatography was used to evaluate the impact on the environment (mobility in soil expressed as soil-water partition coefficient, log Koc; bioconcentration factor in aquatic organisms, log BCF) of several cosmetic raw materials - sunscreens, preservatives and vitamins. The retention parameters RM0 (RM extrapolated to zero concentration of an organic modifier in a mobile phase), S (slope), PC1 (1st principal component) and RM75% (single TLC run parameter for mobile phases containing 75% (v/v) of an organic modifier) obtained for six organic modifiers (methanol, acetonitrile, THF, acetone, dioxane, DMF) were used as the sole descriptors or combined with calculated physico-chemical properties (PSA – polar surface area; MW – molecular weight; VM – molar volume) of studied compounds.The chromatographic parameters considered in this study are, generally speaking, good predictors of the compounds’ mobility in soil or the affinity for aquatic organisms. The parameters RM0, S and RM75% obtained for THF, dioxane and acetone may be used to investigate even very lipophilic compounds. RM75% is of a little bit limited use but it should be considered a time- and cost-effective alternative to the chromatographic parameters obtained by extrapolation or interpolation methods. In the case of some environmental parameters investigated in this study additional descriptors (PSA) have a significant influence on the quality of correlations.