3rd TAGRA

Abstract
Carbon nanotubes (CNTs) have attracted considerable attention as sorbent materials for the extraction and preconcentration of organic and inorganic compounds because of their high surface area and adsorption capacity. In this study, a solid-phase extraction method based on functionalized carbon nanotubes was developed for the extraction and determination of two benzodiazepines, diazepam and lorazepam, from aqueous samples. Single-walled carbon nanotubes (SWCNTs) were chemically functionalized with carboxyl groups, and their surface was further modified using Silane A174 through a sol–gel process. The functionalized sorbent was characterized by Fourier-transform infrared (FTIR) spectroscopy. Gas chromatography coupled with mass spectrometry (GC–MS) was employed for the separation and quantitative determination of the target analytes in selected-ion monitoring (SIM) mode. Experimental parameters affecting the extraction efficiency, including pH, extraction and desorption solvents, extraction time, sorbent amount, and adsorption and desorption temperatures, were systematically optimized. Under the optimized conditions, the proposed method exhibited satisfactory extraction performance for both benzodiazepines. The limits of detection were 26.74 and 475.91 ppb, while the limits of quantification were 158.64 and 76.24 ppb for lorazepam and diazepam, respectively. The results indicate that functionalized CNTs can serve as suitable sorbents for the extraction and preconcentration of benzodiazepines from aqueous samples.