Adaptation of a new pneumatic nebulizer for sample introduction in ICP spectrometry

A new pneumatic nebulizer, the pneumatic extension nozzle ( PEN), originally developed in technical laboratories, mainly for the production of rock and glass wool, is applied for sample introduction in ICP-OES. The droplet formation process under various operating conditions and geometries was investigated using a transparent enlarged model of the PEN. For the application in ICP spectrometry the geometry of the PEN was optimized and miniaturized with the aid of similarity theory. In comparison with a standard concentric nebulizer the miniaturized PEN generates an aerosol with a twice higher mass fraction of droplets with diameters D < 10 mu m. An empirical model for the prediction of the mean droplet diameter is presented, using the nozzle diameter as a linear size scale. This model enables a better fit to experimental data compared with existing models. Applying the miniaturised PEN to a simultaneous ICP-OES instrument lowers the detection limits up to a factor of 3.5 depending on the element. The new pneumatic extension nozzle can be easily adapted to existing ICP-OES instruments.