ICP SPECTROMETRY AND ULTRASONIC NEBULIZAT ION

The use of ultrasonic nebulization in inductively coupled plasma optic al emission spectrometry (ICP-OES-USN) allows an increased sensibility for trace element detection, compared to the traditionally used pneum atic nebulization. The effects of the sample flow rate and of the gas flow rate of the spray chamber on the intensity of the emission signal were measured for Ni, Cd, Pb, Co, Cu, Mo and Zn in HCl (1M) matrix. T he results showed that the gas flow rate of the spray chamber had a si gnificant effect on the net signal intensity with an optimum ratio sig nal emission/background between 0.7 and 1.0 l.min-1 according to the e lement. On the other hand, the sample flow rate had less incidence, it could be low, between 1.25 and 1.50 ml.min-1. without important loss of the signal. The effect of the torch power on the intensity of the e mission signal was studied, in ultrasonic nebulization, for Pb, Zn, Ni , Cu, Mo. Cd and Co in HCl (1M) matrix. An increase in torch power wit hin the range of 740-1000 W, led to an increase in both the net signal and the background, but with a larger effect on the background. The i ncidence of the line character (atomic or ionic) on the relation torch power - emission signal intensity, for Cd and Ni was also shown. The power effect on the emission intensity was not only dependent on line character but also on the nature of the element.