Effect of the operating parameters on second scale time correlation between lines of the same element using axially viewed inductively coupled plasma-multichannel-based emission spectrometry

The influence of power and carrier gas flow rate on time correlation between lines of the same element was studied, using simultaneous measurements with multichannel detection and axially viewed ICP-AES. Both correlation between lines and improvements in the R.S.D. values were calculated to evaluate the link between correlated signals and improved R.S.D. values but also to have a look at the influence of the magnitude of the relative fluctuations of the signals. A dual-view Optima 3000 ICP system was used to permit the simultaneous determination of atomic and ionic lines of nine elements on a wide range of energy. Under suitable conditions, quite good correlations were observed between lines, providing improvements in the repeatability of the signals, regardless of the nature of these lines. Particular behaviors were found for atomic lines of excitation energies higher than 5 eV, for the correlation between the Mg 202.582 nm atomic line and each Mg ionic line and also for Sr lines. Magnitudes of the relative fluctuations of the lines have shown to play a major role both on the correlation and on the improvement in the R.S.D. values. Differences of more than 15% in the magnitude of the relative fluctuations of the two signals will lead to a degradation of the correlation, causing a decrease of the improvement in the repeatability. A decrease of the improvement was observed even if the correlation between lines was not affected.