LIBS limit of detection and plasma parameters of some elements in two different metallic matrices

Abstract

In the present work a detailed study has been performed on the effect of the matrix on the limit of detection (LOD) and the plasma parameters of the laser induced breakdown spectroscopy (LIBS) technique. The LOD of magnesium, silicon, manganese and copper as minor elements was evaluated in aluminium standard sample alloys compared to the values of the LOD of the same elements in standard steel alloys. The effect of changing the matrix on the laser induced plasma plume parameters, namely the plasma temperature T_e and the electron density N_e, has been also studied. Calibrations were achieved for the four elements with linear regression coefficients between 98–99% on average. According to the obtained results Mn and Cu have the lowest LOD in the steel alloy matrix, while Mg has much lower LOD in the aluminium alloy matrix. These results may be interpreted in view of the compatibility of the physical properties of the elements existing in the same matrix. Approximately similar electronic structure and values of melting point, density, atomic weight, etc., may facilitate better conditions for energy transfer within the matrix. From the application view point, it is possible for LIBS in the on-line industrial process control to follow up only a single element (that with the lowest LOD in such matrix) as a marker for the correct alloying in metals and mixing in pharmaceuticals.