▎ 摘　　要

NOVELTY - A titanium wire is hydroxylated to form dense hydroxyl groups. A silicon oxide film is then formed by silylating after removing free hydroxyl ions. N,N'-Dimethylformamide and N,N'-dicyclohexylcarbodiimide are mixed with carboxylated graphene powder to obtain a coating liquid. The silylated wire is dried and immersed in the coating liquid, and carboxyl group is condensed with silylating agent. The wire is dried and processes are repeated several times. The carboxylated graphene coating is reduced and aged, to form a titanium-based graphene coating. USE - Preparation of titanium-based graphene coating for solid-phase microextraction head used for extracting trace amount of phthalate in different water samples e.g. running water, underground water, and lake water, in analytical chemistry and environmental analysis. ADVANTAGE - The method is simple and convenient, enables thickness control, and provides uniform and stable coating having excellent high-temperature resistance. The obtained coating enables efficient extraction of trace amount of phthalate in different water samples. The detection limit is 0.03 mu g/L, the reproducibility is 2.2-12.6%, the marked recovery rate is 73.8-104.5%, and the repeated extraction frequency is more than 200 times. DETAILED DESCRIPTION - A titanium wire of length 10-15 cm used as the solid-phase microextraction head base, is ultrasonically cleaned using an organic solvent, washed with deionized water, and naturally dried in air. In a water bath, the titanium wire is hydroxylated using alkaline sodium hydroxide solution to form dense hydroxyl groups on the surface. A silicon oxide film is then formed by silylating for 12 hours after removing free hydroxyl ions from the wire surface by washing with hydrochloric acid, methanol, and deionized water. N,N'-Dimethylformamide as dispersant and N,N'-dicyclohexylcarbodiimide as crosslinking agent are uniformly mixed with carboxylated graphene powder to obtain a viscous and turbid carrier graphene coating liquid. The silylated titanium wire is oven-dried and immersed in the coating liquid under water-bath condition of 70 degrees C, and the carboxyl group is condensed with the silylating agent bonded to the wire surface. The wire is then dried in air and the processes are repeated several times to a coating thickness of 19-21 mu m. The titanium wire with the coating is loaded in a stainless steel hollow sleeve tube. One end of the sleeve tube far away from the coating is capped using a gas-phase chromatography sample pad, and curing process is carried out. The carboxylated graphene coating is reduced for 12 hours using hydrazine under alkaline conditions and then aged, to form a titanium-based graphene coating on the microextraction head.