Magnetic-aminopropyltriethoxysilane-sulfanilamide: A New Functional Sorbent for Selective Preconcentration of Sulfonylurea Antidiabetic Drugs in Biological Samples

Abstract

A highly selective and sensitive analytical strategy was established for the trace quantification of two oral antidiabetic drugs, gliclazide (GLZ) and glimepiride (GLM). The procedure integrates magnetic solid-phase extraction (MSPE) with high-performance liquid chromatography coupled to diode array detection (HPLC-DAD). In this approach, a newly engineered Magnetic-aminopropyltriethoxysilane-sulfanilamide (Fe₃O₄@APTES– Sulfanilamide), was synthesized and utilized as an innovative adsorbent. Sulfanilamide as functional molecule on the surface has been used for the first time in this study. The hybrid structure, consisting of a Fe₃O₄ magnetic core and a sulfanilamide-functionalized silane shell, provides strong binding affinity toward sulfonylurea compounds through synergistic hydrogen bonding and π–π interactions. Optimization studies were carried out to achieve the best extraction efficiency by adjusting experimental variables such as solution pH, adsorption and desorption times, and solvent composition. Under the final working conditions (pH 6.0; desorption with acetonitrile–methanol mixture), both target analytes were effectively preconcentrated prior to chromatographic determination. Separation was accomplished using an isocratic elution system containing 10 % methanol, 40 % phosphate buffer (pH 3.0), and 50 % acetonitrile, with UV detection at 219 and 256 nm. The developed protocol demonstrated excellent linearity, remarkable enrichment factors, and very low detection limits. Precision studies yielded RSD values below 3.5% (n = 3, 100 ng·mL⁻¹). The reliability of the proposed method was further validated by its successful application to both synthetic and human urine samples, giving satisfactory recovery results. This newly designed Fe₃O₄@APTES–Sulfanilamide -based MSPE coupled with HPLC-DAD provides a robust, time-efficient, and eco-friendly platform for the determination of trace oral antidiabetic drugs in complex biological matrices.