Quantification of Trace Metalloids and Metals in Airborne Particles Applying Dynamic Reaction Cell Inductively Coupled Plasma Mass Spectrometry

Abstract

Determination of trace contents of metals and metalloids, monitored in airborne particles for their adverse health and environmental impact or to discriminate pollutant particulate emission sources, requires very sensitive analytical methods. Dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) has been applied to measure ultra-trace elements found in PM₁₀ atmospheric particles in order to determine simultaneously, rapid and accurate concentrations for well known highly interfered isotopes (⁷⁵As, ⁵⁹Co, ⁵²Cr, ⁵³Cr, ⁵⁸Ni, ⁶⁰Ni, ⁷⁸Se, ⁴⁵Sc, and ⁵¹V). The challenge resides in the extremely low content of these elements encountered in PM₁₀ particles, while thorough mineralization procedures in complex matrices are necessary to deal with refractory minerals. The potentially interfering polyatomic ions combining Ar, Cl, F, O, N, and C isotopes were significantly reduced by using NH₃ as the reaction gas in the DRC, optimizing the reaction cell band pass and tuning of the gas flow rate. Standard Reference Material (NIST 1648) as well as real atmospheric samples were analyzed under the best defined conditions to validate and exemplify our methodology. The method detection limits are 450 ng/L for As, 13 ng/L for Co, 1210 ng/L for Cr, 780 ng/L for Ni, 47 ng/L for Se, 22 ng/L for Sc, and 26 ng/L for V. Based on real atmospheric sample measurements, DRC-ICP-MS associated with NH₃ is confirmed as a cost effective technique to produce accurate results during routine working procedures for all these elements except Se.