Aerosol desolvation studies with a thermospray nebulizer coupled to inductively coupled plasma atomic emission spectrometry

Abstract

Two desolvation systems commonly used in ICP-AES have been evaluated when coupled to a thermospray nebulizer. The desolvation systems are: (i) a thermostated spray chamber (TSC) and, (ii) a two-unit desolvation system (TUDS) in which the first unit is a heated single-pass spray chamber and the second one is a Liebig condenser. Both systems were evaluated with aqueous and organic solutions. The temperature of the chamber in the TSC (–5 to 20 °C) and the temperatures of the heated spray chamber (60 to 140 °C) and the condenser (–5 to 20 °C) in the TUDS were taken as variables. To evaluate the effect of these variables on the performance of the desolvation systems, drop size distribution of the tertiary aerosol, solvent and analyte transport rates and emission signal have been measured. Under optimal desolvation conditions, the values of the solvent transport efficiencies were similar for both systems, ranging from 2.3 to 9.5%. Analyte transport efficiency values ranged from 36 to 77% and from 5 to 8% for TUDS and TSC, respectively. TUDS gives rise to higher signals (6 to 7 fold higher) and lower LOD (2 to 11 times lower) than TSC. As regards the solvent nature, the highest emission intensity and lower LOD are obtained with ethanol, followed by water and butan-1-ol. The LOD values obtained with the combination thermospray–TUDS are 2 to 26 times lower than those obtained with a conventional pneumatic nebulizer coupled to the same desolvation system.

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