Desolvation of acid solutions in inductively coupled plasma atomic emission spectrometry by infrared radiation. Comparison with a system based on microwave radiation

摘要

The behaviour of an infrared desolvation system with acid solutions in inductively coupled plasma atomic emission spectrometry (ICP-AES) is evaluated, and the influence of the liquid uptake rate and of the nature and concentration of the acid on the solvent and analyte transport rates and on the analytical figures of merit is studied. The results are compared with those obtained with a desolvation system based on the absorption of microwave radiation. The infrared desolvation system performs best at low sample uptake rates (0.4 ml min~(-1)) and its behaviour strongly depends on the nature and concentration of the solution used. With nitric and hydrochloric solutions, there is almost no effect on the acid concentration of the emission intensity, while for sulfuric and perchloric acids the signal decreases as the acid concentration is increased. These effects seem to be related with the different capability of the acid aerosols to be heated in an IR field. The microwave desolvation system seems to be more prone to matrix (acid) effects, specially when using sulfuric and perchloric acids, resulting in emission intensities which are usually lower than those obtained with the infrared desolvation system, though their limits of detection are quite similar.