Zone Fluidics Derivatization of Thiols Under Flow Conditions by 2-Chloro-1-methylquinolinium Tetrafluoroborate

Abstract

The present investigation reports—for the first time—data on the reaction of the derivatization reagent 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) with thiols under flow conditions. By adopting the concept of zone-fluidics, we examined various chemical parameters of the reaction and applied the stopped-flow technique for kinetic studies. CMQT proved to react rapidly with model thiol compounds under flow conditions and alkaline media, offering promising data for future applications such as liquid chromatography coupled to on-line post-column derivatization. Furthermore, the potential of the reagent was demonstrated by developing an automated flow method for the quality control of methimazole-containing formulations. Following validation experiments, the latter were determined in assay and dosage uniformity quality control tests of commercially available formulations with a limit of detection of 0.24 mg L⁻¹, precision better than 1.5%, and a sampling rate of 30 h⁻¹.

[Supplementary materials are available for this article. Go to the publisher's online edition of Analytical Letters for the following free supplemental resource(s): Additional figures.]

Keywords:

• 2-chloro-1-methylquinolinium tetrafluoroborate
• Derivatization
• Spectrophotometry
• Thiols
• Zone fluidics

Notes

^a LOD estimated based on 3 × SD_b/a, where SD_b is the standard deviation of the blank and a is the slope of the regression line.