Direct Determination of Metals in Soils and Sediments by Induction Heating-Electrothermal Vaporization (IH-ETV) Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES)

Abstract

The application of an induction heating (IH) electrothermal vaporization (ETV) sample introduction arrangement for the determination of As, Cd, Cu, Mn, Pb, and Zn in soils and sediments by inductively coupled plasma-optical emission spectrometry (ICP-OES) is presented. Samples were deposited either directly as a solid or by means of slurry sampling into graphite cups that were then positioned in a radio-frequency (RF)-field and vaporized in a carrier flow of 15% (v/v) SF₆-Ar. Four certified reference materials (CRMs) were examined: two soil samples—SRM 2710 and SRM 2711 (NIST); and two marine sediments—MESS-2 and PACS-2 (NRC Canada). In general, sample delivery was simpler and observed signal precision was better with slurry sampling when compared to the analysis of the solid directly, with peak area RSDs ranging from 4–16% (n = 6). Plots of intensity vs. certified concentration for the four CRMs were linear with log-log slopes of 0.98–1.02 and r² values ≥ 0.995 for As, Cu, Pb, and Zn. Recoveries of 80–105% were achieved for the above elements in SRM 2711 by using an external standards curve constructed from the 3 remaining CRMs. Aqueous standard solutions were used for the analysis of all 4 CRMs by standard additions, resulting in recoveries ranging from 54–139% (average recovery of (101 ± 15)%) across all six determined elements in all four samples.