Time-resolved laser-induced plasma spectrometry for determination of minor elements in steelmaking process samples

A pulsed Nd:YAG laser operating on the fourth (266 nm) and second (532 nm) harmonics has been used to generate plasmas on the target surface in air at atmospheric pressure. The influence of wavelength on quantitative analysis of 4 minor elements in stainless steel samples (Si, Ti, Nb and Mo) was investigated. Stainless steel samples with different elemental concentrations were prepared and analyzed by laser-induced plasma spectrometry (LIPS). The effect of laser wavelength on analytical figures of merit (calibration curves, correlation coefficients, linear dynamic ranges, analytical precision, and accuracy values) was found to be negligible when internal standardization (an Fe line) and time-resolved laser-induced plasma are employed. For both wavelengths, the calibration curves presented a good linearity and an acceptable linear dynamic range in the concentration interval investigated. For the four elements studied, limits of detection lower than 150 microg g(-1) were achieved. To evaluate the influence of wavelength on precision and accuracy, a set of fifteen high-alloyed steel samples from different stages of steelmaking process have been analyzed. Finally, the long-term stability of the analytical measurements for Mo with 532 nm wavelength has been discussed. RSD values were lower than 5.3% for the elements studied.