Laser ablation ICP-MS of size-segregated atmospheric particles collected with a MOUDI cascade impactor: A proof of concept

Abstract

A widely used instrument for collecting size-segregated particles is the micro-orifice uniform deposit impactor (MOUDI). In this work, a 10-stage MOUDI (cut-point diameter of 10μm to 56nm) was used to collect samples in Ljubljana, Slovenia, and Martinska, Croatia. Filters, collected with and without rotation, were cut in half and analyzed for nine elements (As, Cu, Fe, Ni, Mn, Pb, Sb, V, Zn) using laser ablation ICP-MS. Elemental image maps (created with ImageJ) were converted to concentrations using NIST SRM 2783. Statistical analysis of the elemental maps indicated that for submicron particles (stages 6-10), ablating 10% of the filter (0.5cm2, 20min ablation time) was sufficient to give values in good agreement (±10%) to analysis of larger parts of the filter and with good precision (RSE<1%). Excellent sensitivity was also observed (e.g., 20±0.2pgm-3V). The novel use of LA-ICP-MS, together with image mapping, provided a fast and sensitive method for elemental analysis of size-segregated MOUDI filters, particularly for submicron particles.