Smart thermal behavior of tripeptide leucyl-leucyl-leucine towards vapors of binary mixture of benzene and tetrachloromethane

Abstract

A new method for the determination of benzene vapors in a two-component mixture was proposed. This method is based on smart behavior of L-leucyl-L-leucyl-L-leucine (LLL) crystals, which are able to remember the included benzene. This memory is revealed as the sequential endo- and exothermic effects on the DSC curve under heating of LLL powder saturated with vapors of benzene in the temperature range above the endset point of benzene release. The enthalpies of endo- and exothermic effects are proportional to the benzene content in its binary vapor mixture with tetrachloromethane used to saturate the LLL powder. The reasons of the LLL memory are explained and the possibility to control the polymorphic state of the tripeptide using organic vapors was shown. The observed specific properties of LLL tripeptide may be used for qualitative and quantitative analysis of benzene in its mixture with other organic substances.