Ferrofluid-Based Preconcentration And Ultra-Trace Determination Of Pt, Pd, Au, And Ag In Complex Matrices Using Inductively Coupled Plasma Mass Spectrometry

: This study presents a method for the ultra-trace determination of several noble metals (Pd, Pt, Au, and Ag) in geological samples through selective preconcentration using a ferrofluid. Specifically, Fe 3 O 4 magnetic nanoparticles (MNPs) coated with silica and titania and functionalized with 3-mercaptopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane were employed for the selective sorption of analytes. After injecting the ferrofluid into an aqueous sample, the functionalized MNPs adsorbed the target analytes within 5 min. The analyte-carrying MNPs were then separated using an external magnet, followed by elution using 10% v/v aqua regia + 3% thiourea. The eluate was analyzed using inductively coupled plasma mass spectrometry. The effects of sample solution pH, eluent composition, elution time, and elution volume on the preconcentration factor were investigated. Under optimized conditions, the detection limits were improved by factors of 8 to 15 for Pt, Pd, Au, and Ag, compared to those obtained without preconcentration. The accuracy of this method was verified by analyzing a certified reference material (CDN-PGMS-29) of ore containing noble metals, and the measured concentrations were consistent with the certified values based on a Student’s t-test at the 95% confidence level.