CHARACTERIZATION OF A NEW SINGLE-BORE HIGH-PRESSURE PNEUMATIC NEBULIZER FOR ATOMIC SPECTROMETRY .1. DROP SIZE DISTRIBUTION, TRANSPORT VARIABLES AND ANALYTICAL SIGNAL IN FLAME ATOMIC-ABSORPTION SPECTROMETRY

The subject of this study was the behaviour of a new high-pressure pneumatic nebulizer, with a single-bore for the passage ot both liquid (sample) and gas (nebulizing gas) streams, used as a method for introducing samples in atomic spectrometry. As a standard for comparison, we used a Meinhard-type concentric pneumatic nebulizer and a flame atomic absorption spectrophotometer to obtain the analytical signal. A study was made of the effect of both the liquid and gas flows as well as that of the outlet section on the following experimental parameters: droplet-size distributions of primary and tertiary aerosols; total analyte mass and solvent mass transport rates; and characteristics of the analytical signal (sensitivity, limit of detection, short- and long-term stability and memory effects). The results obtained indicate that, for the same liquid and gas flows, the new single-bore high-pressure pneumatic nebulizer generates aerosols whose primary and tertiary droplet-size distributions are finer than those obtained with a Meinhard-type nebulizer. This leads to higher values in total analyte mass and solvent mass transport rates, while the characteristics of the analytical signal in flame atomic absorption spectrometry are improved. The operating conditions under which the new nebulizer shows the greatest improvement in comparison with the Meinhard type are: low gas flow; high liquid flow: and small outlet section.