On-Chip Preconcentration and Determination of Magnetite Nanoparticles in Water Based on Paired Emitter-Detector Diode Photometry

Iron oxide nanoparticles have been widely used in various fields of study. Due to the increasing use of these nanoparticles, it is important to develop sensitive methods for measuring these nanoparticles in real samples. In this research, a method was developed to measure magnetite nanoparticles using microfluidics science and paired emitter-detector diode-based photometry. The basis work of the designed system is based on the magnetic preconcentration of nanoparticles inside the microchip, dissolution by acid, and creation of a signal through the formation of an iron-thiocyanate complex. The validation results of the method showed that the linear range of the method is from 1.0 to 6.0 ppm with appropriate accuracy (recovery percentages: 104.0% and 95.6%) and precision (coefficient of variation: 0.17% and 0.15%), which is satisfactory for measuring trace amounts of magnetic nanoparticles. The limits of detection and quantification were obtained as 0.3 and 0.9 ppm, respectively. Compared to previously reported methods, the developed method provides higher sensitivity and simpler instrumentation of lower analysis cost by the use of a microfluidic chip for magnetic preconcentration of magnetic nanoparticles, washing, dissolution, and photometric determination.