Analysis of trace elements in complex matrices (soil) by Laser Induced Breakdown Spectroscopy (LIBS)

Direct spectro-chemical analysis of trace elements in complex matrices like minerals and soil is usually difficult because of possible interference from the intense background spectrum of the major components generated in the plasma. Optimization of the Laser Induced Breakdown Spectroscopy (LIBS) technique is essential for routine analysis of such samples. In the present work, we have shown that low detection limits can be achieved for trace elements like copper, zinc, and calcium in soil samples by using high resolution echelle spectrographs coupled to the LIBS system, and eliminating the background by subtraction of a suitable matrix "blank" spectrum. It is also shown that the LOD (limits of detection) can be further reduced by suitable data processing techniques like signal addition from multiple lines provided by the wide-range echelle system and use of correlation function calculation with a pure element spectrum. The validity of our LIBS technique was confirmed by conventional Atomic Absorption Spectroscopy (AAS) analysis for the same analyte after pre-concentration.