On-line microdialysis-nano-Au/TiO2-high-performance liquid chromatography system for the simultaneous determination of cobalt and nickel in water.

An on-line configuration of microdialysis (MD), Au/TiO2 nanoparticle preconcentration, and high-performance liquid chromatography-ultraviolet (HPLC-UV) detection method was developed for the simultaneous measurement of cobalt (Co) and nickel (Ni) concentrations in water. The sample matrix was first cleaned with an MD system using a MD probe. A continuously flowing dialysate stream was introduced into tubing coated with Au/TiO2 nanoparticles to adsorb metals, followed by elution by an acidic eluent. The enriched samples were derivatized on-line using 8-hydroxyquinoline. The separation of Co and Ni were achieved by using a LC-C18 column. The three aforementioned system components were connected on-line using a valve control. The UV detection was performed at 319nm. Validation experiments demonstrate good linearity, precision, accuracy, and recovery. The proposed method offers a simple and reliable procedure to determine the levels of Co and Ni in environmental water samples. Moreover, the methodology described in this study adheres to the concept of green chemistry, including the absence of organic solvents in the MD sampling and extraction processes. To the best of our knowledge, the proposed method is the first reported on-line connection of MD, Au/TiO2 nanoparticle tubing, and HPLC devices for the measurement of Co and Ni concentrations in water.