Pre-concentration of trace metals on centrifugal microfluidic discs with direct determination by laser ablation inductively coupled plasma mass spectrometry

Abstract

Solid Phase Extraction (SPE) is commonly used for pre-concentration and matrix removal in trace metal determinations. We present a novel centrifugal microfluidic device for field sampling and on-site pre-concentration of water samples. Metal-8-hydroxyquinoline complexes are adsorbed onto miniature C₁₈-bonded silica gel columns on centrifugal microfluidic discs. Laser Ablation (LA) is used to directly vaporize the analytes from the column, instead of eluting the pre-concentrated analytes for introduction in an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) by conventional solution nebulization. Absolute detection limits ranging between 0.1 and 12 ng were obtained for Ni, Cu, V, Pb and Co in drinking water Certified Reference Materials (CRMs). These centrifugal devices require only 1–600 µL samples and necessitate no more than a simple motor to actuate fluid flow. The discs can be used to perform multiple extractions simultaneously as well as allowing the easy storage of samples before transport to the laboratory for LA-ICP-MS analysis.