Emission Characteristics of Okamoto-cavity Microwave-induced Plasma in Direct Introduction of Organic Solvents and the Application to the Analysis of MIBK Extract from Iron-matrix Samples (in Japanese)
Tetsu-to-Hagane, 91 (2005) 471-477
Abstract
An Okamoto-cavity microwave-induced plasma (MIP) with a nitrogen-oxygen gas mixture was employed as an atomization and excitation source for emission analysis when organic solvent samples were directly aspirated The mixed gas plasmas could be maintained with a high robustness against the loading of organic solvents such as ethanol and 4-methyl-2-pentanone (MIBK). Also, the introduction of the organic solvents exerted little influence on the emission characteristics of the plasma; the atomic-to-atomic and the ionic-to-atomic intensity ratios of various emission lines were a little varied by introducing organic solutions containing different concentrations of ethanol. This is probably because the organic solvent can be easily removed due to reactions with active oxygen species in the MIP. After test solutions containing Al, Co, Cr(III), Cu, Fe(III), Mo(VI), Ni, and Pb were extracted with MIBK, both the aqueous phase and the organic phase were aspirated into the plasma, giving calibration curves having good linearity, either from the aqueous phase for Al, Co, Cr, Ni, and Pb or from the organic phase for Fe and Mo. This effect can be explained from the partition coefficients of these elements between in MIBK and in water.
KeyWords: microwave induced plasma; Okamoto cavity; optical emission spectrometry; emission characteristics; direct loading of ethanol; MIBK extraction