Influence of the spray chamber design for vapor-based liquid sample introduction at room temperature in ICP-AES

Abstract

This paper describes a new concept for the introduction of very low liquid sample volumes in ICP-AES. Three single pass low inner volume spray chambers have been designed and characterized: two cylindrical ones of different inner volumes, 4 and 8 cm3, and a spherical type one, with 11 cm3. In every case a high efficiency nebulizer (HEN) has been used to generate the aerosol, and comparison with a conventional cyclonic spray chamber has been performed. The chambers were designed to enhance solvent evaporation within the spray chamber at liquid flow rates below 100 µl min−1, and to obtain a simple aerosol path. The aim was to combine the advantages of a spray chamber and those of a so-called direct injection nebulizer (DIN). The best analytical results, viz., repeatability, signal-to-background ratio and limits of detection, were obtained with the 8 cm3 single pass chamber. Results were usually improved when compared with the conventional cyclonic spray chamber. It has also been found that the interferences due to organic solvents (ethanol, formic and acetic acid), aqueous solutions and mixtures thereof (water–ethanol solutions) were less severe for the single pass spray chamber than for the cyclonic one.