Comparison of two lab-made spray chambers based on MSIS™ for simultaneous metal determination using vapor generation-inductively coupled plasma optical emission spectroscopy

The objective of this study is to evaluate the performance of two lab-made systems based on the Multimode Introduction System (MSIS™) and the modified MSIS™, to generate and introduce vapors of Ag, Cu, Cd, Cu, Ni, Sn, Zn, and also Au in the ICP torch. An univariate procedure was used to select the optimized working conditions (Ar flow, sample, reductant and waste flows, and reagent concentrations). Optimum conditions for working with modified MSIS were: nitric acid concentration 0.35 M, 8-hydroxyquinoline concentration: 40 mg L−1, sodium borohydride concentration: 1.75% (w/v) + 0.4% (w/v) NaOH, argon purge flow to sweep the vapors to the torch: 1.2 L min−1, sample flow and sodium borohydride flows: 2.3 L min−1; waste flow: 7.7 mL min−1. For the optimum working conditions for lab-made MSIS in dual mode the concentration of 8-hydroxyquinoline was 225 mg L−1, the Ar purge flow was 0.75 L min−1, and the conventional nebulization flow was 2.3 L min−1. The sensitivity obtained was higher using the lab-made MSIS than using the lab-made modified MSIS or a forced outlet gas–liquid separator. The limits of detection were better for Au, Cd, Sn than those obtained using conventional nebulization; the measurements were precise (RSDs ≤ 5% in dual mode) and a good accuracy was obtained in the determination of Cd, Cu, Ni and Zn in a wastewater reference material using aqueous calibration and the lab-made MSIS in dual mode.

Figure optionsDownload as PowerPoint slideHighlights
► Two lab-made systems based on MSIS™ were evaluated to generate vapors of Ag, Au, Cd, Cu, Ni, Sn and Zn.
► The present study provides data about Au in a dual-mode sample-introduction system.
► The two systems were compared with the use of a forced outlet gas–liquid separator and conventional nebulization.
► The LODs were lower for Au, Cd and Sn using lab-made MSIS working in dual mode.
► 8-Hydroxyquinoline was used to improve volatilization, and detection was performed by ICPOES.