Thermoanalytical study of Nα-benzoyl-l-argininate ethyl ester chloride

Nα-benzoyl-l-argininate ethyl ester chloride (BAEEH+·Cl−) has been used as a model drug in the development of polymeric delivery systems for peptides and proteins. In this study, crystalline BAEEH+·Cl− was characterized by different thermoanalytical techniques. The main thermal events were identified by modulated differential scanning calorimetry (MDSC). Polarized light thermomicroscopy (PLTM) showed that no phase transitions but fusion occur before thermal decomposition. A crystalline phase could not be obtained from the melt in cooling/heating cycles between 150 °C and −150 °C, at 10 °C min−1 scanning rate. The thermal stability and the non-isothermal kinetic analysis of the thermal decomposition were studied by conventional and high resolution modulated thermogravimetric analysis (HiRes-MTGA). Depending on the conditions of the study, the decomposition starts in the range from 197 °C (HiRes-MTGA at ϕ = 2 °C min−1) to 261 °C (TGA at 20 °C min−1). It was found that the first stage of the decomposition process can be described by the kinetic triplet Ea = 142 kJ mol−1, A = 1.86 × 1011 s−1, and f(α) = (1 − α)2.78.