Influence of solvent physical properties on drop size distribution, transport and sensitivity in flame atomic absorption spectrometry with pneumatic nebulization

Abstract

The aim of this paper has been to study the influence that the main physical properties of the solvent (surface tension, viscosity and volatility) exert on the magnitudes of the following parameters: the drop size distribution of the primary aerosol; the transport efficiencies for analyte and solvent; and the sensitivity in flame atomic absorption spectrometry with pneumatic nebulization. Two series of experiments have been carried out, one with pure solvents and another with methanol–water mixtures of variable composition, always using 2 µg ml^–1 Mn as the analyte. The results show that surface tension and, to a lesser extent, viscosity determine the mean size of the distribution. The span, on the other hand, does not appear to follow any simple relationship with the physical properties of the solvent. The analyte transport rate is improved by a high solvent volatility and also by a distribution with a small mean drop size and a high span. Absorbance values are essentially consistent with analyte transport rates, this tendency being modified by the diluting effect of the solvent carried to the flame.