Applications of laser-induced plasma spectroscopy to human tissue, plants and ores

In Laser-Induced Plasma Spectroscopy (LIPS), a focused, nanosecond laser pulse of high irradiance strikes the surface of the target, which instantly increases the surface temperature above the vaporization temperature. The dissipation of this energy through vaporization is relatively slow compared to the rate at which energy is deposited. Therefore, before the surface layer vaporizes, the underlying material reaches a critical temperature and pressure, causing the surface to explode and a transient plasma is formed. The light given off by the plasma is spectrally resolved and the atomic line spectrum is subsequently analyzed and calibrated in order to determine elemental concentrations in the sample. The main goal of this dissertation was to apply LIPS to the analysis of new materials.A brief review and fundamental investigations are given in Chapter 2 and Chapter 3 for better understanding the LIPS.A new, novel sample preparation method for LIPS in Chapter 4 involves applications of loose powder directly to double-sided tape on glass slides with measurement by LIPS. The new sample preparation method was compared with the traditional sample preparation method (pellets) for the measurement of Mn and Si in iron ore. The new sample preparation method has potential for on-line and remote analysis of iron ore with minimal sample preparation.In Chapter 5, the novel sample preparation approach was applied to direct multielemental analysis of solid plant leaves for major-to-trace elements in different NIST standard reference materials.The unique use of LIPS to analyze trace levels of Zn in the stratum corneum of human skin is presented in Chapter 6. Good linearity and a detection limit of 0.3 ng/cm2 were obtained. This methodology was also used to evaluate the effectiveness of barrier creams (skin protective creams) on human skin. The results, which provided a facile and rapid screening of the effectiveness of skin barrier creams to metal ion penetration, are presented in Chapter 7.