Ethyl-propiolate as a novel and promising analytical reagent for the derivatization of thiols: Study of the reaction under flow conditions

The present investigation demonstrates the potentials of ethyl-propiolate (EP), a novel derivatizing reagent for thiols. To the best of our knowledge this is the first systematic study of EP in analytical chemistry. The reaction was investigated under flow conditions using sequential injection (SI) analysis and UV detection at 285 nm. The reaction kinetics was affected by parameters such as the pH, the concentration of EP and the temperature and was thoroughly examined exploiting stopped-flow experiments. Cysteine (CYS) and captopril (CAP) were selected as model thiolic compounds in terms of chemical structures. Finally, the applicability of EP as a derivatization reagent for analytical purposes was demonstrated by the development and validation of a novel automated assay for the determination of CAP in pharmaceuticals.