The key requirements are outlined for an effective pre-column derivatization reagent used in the HPLC determination of chromophore-free organic compounds. Nitrofluorostyrenes, dichlorostyrenes, and diethyl 2-(4-nitrobenzylidene) malonate were studied as new reagents. Diethyl 2-(4-nitrobenzylidene) malonate was selected as the optimal reagent. 2-Methylmercaptoacetate was derivatized as a test analyte under mild conditions for 20 min at room temperature. The reaction proceeded to completion, forming a single product. The detection limit of 2-methylmercaptoacetate decreased by a factor of 67 (to 15 ng mL–1) compared to the initial value.
Karpeev et al. (Wed,) studied this question.