Alternative Approaches Applied to Inductively Coupled Plasma Techniques: Multi‑Flow and Two-Flow Calibration

Raquel Machado,Fernanda Pinheiro,Edenir Pereira‑Filho,Ana Beatriz Silva,Daniel Andrade,George Donati,Ana Rita Nogueira,Charles Williams

doi:10.21577/0103-5053.20200235

Raquel Machado, Fernanda Pinheiro + Show 6 more

Open Access

https://doi.org/10.21577/0103-5053.20200235

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Abstract

Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibration standard solution at several different nebulization gas flow rates (Q), which normalizes plasma conditions and minimizes matrix effects. In the present study, MFC was evaluated, for the first time, applied to inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) to analyze different and complexmatrix samples. Al, As, Cd, Cr, Cu, Mn, Pb, and Zn were determined by ICP OES, while As, Cd, Co, Cu, Hg, Mo, Mn, Ni, Se, Sb, Pb, and V were determined by ICP-MS. MFC results were compared with those obtained using external standard calibration (EC) for both techniques and in all cases, MFC showed equal or superior accuracy (recoveries between 80-120%) compared to EC, and lower relative standard deviation (RSDs ≤ 10%). Several tests were also performed using only two nebulization gas flows to build linear models for calibration (called two-flow calibration, TFC) and the accurate results (recoveries ranged from 80 to 110% for ICP OES and from 81 to 102% for ICP-MS) suggests that this strategy can be also applied, resulting in a method with high sample throughput.

Highlights

Argon plasma-based techniques such as inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) are considered state-of-the-art for elemental determination
Considering some of the recently described calibration approaches to compensate for matrix effects in ICP OES and ICP‐MS, Multi-flow calibration (MFC) is the only one that allows the use of a single calibration standard, with no matrix matching involved.[19]
Multi-flow and two-flow calibrations were evaluated as strategies to improve the accuracy of elemental determination by ICP OES and ICP-MS for several matrices

Summary

Introduction

Argon plasma-based techniques such as inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) are considered state-of-the-art for elemental determination These techniques are versatile and may be successfully employed for a wide range of matrices.[1,2] Despite its advantages (e.g., sensitivity, multi-elemental capabilities, wide linear range of detection, and versatility), some drawbacks still exist such as spectral and non-spectral interferences that can compromise the reliability of results and the analytical performance.[3,4]. Common for both of these spectroanalytical techniques, spectral interferences are more pronounced in ICP-MS determinations. These interferences are usually related to matrix effects, which are caused by

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