Scavenging of benzodiazepine drugs from water using dual-functionalized silica nanoparticles

This study introduces newly developed dual functionalized silica nano-particles (DFSNPs) for drug analysis. DFSNPs were used to extract and pre-concentrate benzodiazepine drugs from water samples. This technique is based on the dispersion of 100 nm diameter silica nanoparticles bi-functionalized by octadecyl and glycidoxy in water samples to extract the benzodiazepines without the use of hand or mechanical agitation. First, uniform spherical silica nanoparticles with a diameter of 100 nm were prepared via a sol-gel process using an appropriate catalyst, solvent and precursor concentration. The prepared silica nanoparticles were subsequently treated with silane coupling agents octadecyltrichlorosilane and glycidoxypropyltrimethoxysilane (3GPTS) to immobilise both octadecyl and glycidoxy functional groups. The attachment of 3GPTS to the surface of the silica nanoparticles after hydrolysis improved the surface hydrophilicity and consequently increased the dispersion of the particles in water samples. The dual-functionalised nanoparticles were then used to extract and pre-concentrate chlordiazepoxide, diazepam, fludiazepam, nitrazepam and tetrazepam. The results showed that the recovery percentage depends primarily on the pH and the contact time. The recoveries ranged from 62 to 99% with an equilibration time of 45 min.