Analysing heavy metals using laser induced breakdown spectroscopy technique

Abstract

Analyzing heavy metals in polluted water using conventional method by chemical technique is difficult because sample preparation involves a lot of chemical. As an alternative to overcome the drawback, laser induced breakdown spectroscopy is introduced. The aims of this project is to analyze heavy metals commonly found in sea water using a q-switched Nd:YAG laser. The laser was focused using two lenses, concave lens was used to diverge the beam and then bring to merge by camera lens with wide angle of 28 mm focal length. An optical breakdown occurred associated with plasma formation at the focal point. Heavy metal sample comprised of solid form and powder. The powder sample was deposited on glass slide by PVD technique. The heavy metal sample was located at the focal point in the air and exposed by laser in repetitive mode with frequency of 10 Hz. The plume plasma formation on the metal sample was visualized using CCD camera. The spectrum produced after laser-metal interactions were recorded via spectrum analyzer. The line spectra were manifested on the screen and analyzed by comparing to data base. Each line represents the element contained in the tested metal. The highest signal indicates the major element contains from the tested heavy metal. Finally, the analyzed heavy metals were summarized in a histogram for comparison purposes.