EFFECT OF LONG-CHAIN SURFACTANTS ON DROP SIZE DISTRIBUTION, TRANSPORT EFFICIENCY AND SENSITIVITY IN FLAME ATOMIC-ABSORPTION SPECTROMETRY WITH PNEUMATIC NEBULIZATION

The variations of the droplet size distribution, transport efficiency and absorbance which arise as a consequence of the addition of long-chain surfactants to aqueous solutions of Mn(II) were studied. The results show that the drop size distribution of the primary aerosol does not change on increasing the surfactant concentration, irrespective of whether cationic or anionic long-chain surfactants are used. Concomitantly, neither transport efficiency nor absorbance change. A mechanism is also suggested in order to explain these results, based on the following points: (i) surfactant molecules require a certain period of time in order to redistribute on the new surface that is being generated during the nebulization step; and (ii) this time increases as the length of the hydrophobic chain increases.