Aerosol dilution as a new sample introduction strategy for microwave-induced plasma optical emission spectrometry

Abstract

A new sample introduction method using aerosol dilution for microwave-induced plasma optical emission spectrometry (MIP OES) is presented. Signal emissions from N2+ and OH species were monitored for plasma diagnostics and quantity of solvent plasma load (QSPL). The N2+/OH signal intensity ratio demonstrated that aerosol dilution is a desolvation process which can reduce the QSPL, increasing plasma energy. Efficiency of the system was observed with solutions containing the easily ionizable element (EIE) Na, without important alteration of the plasma physics at concentrations up to 5 g L−1. Atomic and ionic lines of Cr, Mn, V and Zn in saline solutions proved to have distinct variations. Despite the lower amount of analyte introduced, the LOQs of these elements were similar to the ones obtained from conventional nebulization. The analysis of two CRMs (fertilizer, NIST 695 and tomato leaves, NIST 1573a) resulted in percentage recoveries within 90–130%. Aerosol dilution in MIP OES (AD-MIP OES) brings increased robustness to the technique, once complex matrices can be introduced with the advantage of suppressing matrix interferences. Additionally, the sample is less prone to dilution error, and costs are saved due to increased life span of consumables since less sample matrix is introduced in the plasma.