Synthesis and Characterization of Amide Stationary Phases for the Determination of Sulfonamides by Sequential Injection Chromatography

ABSTRACT

The synthesis of amide (butyl, cyclohexyl, and phenyl) modified silica and the use as stationary phases in sequential injection chromatography are described. The system was tested on the isocratic separation of seven sulfonamides (sulfachloropyridazine, sulfadimethoxine, sulfamethazine, sulfamethoxazole, sulfamethoxypyridazine, sulfaquinoxaline, and sulfathiazole) using each stationary phase with mobile phases composed of acetonitrile/water at a flow rate of 0.45 mL min⁻¹. A mixed mode retention mechanism of sulfonamides in the stationary phases was obtained, including dipole-dipole, π-π, and hydrogen bonding interactions. The most appropriate phase for the separation of sulfonamides was phenylamide. The chromatographic behavior was confirmed using density functional theory of the interaction between sulfamethoxazole and the stationary phases.

KEYWORDS:

• Density functional theory
• sequential injection chromatography
• solid phase interaction
• sulfonamides

Acknowledgment

We gratefully acknowledge the computer time from Dirección General de Computo y de Tecnologías de Información y Comunicación (DGCTIC) at Universidad Nacional Autonoma de Mexico and the Laboratorio de Visualizacion y Computo Paralelo at UAM—Iztapalapa for the access to its computer facilities.