Elementar LIBS Analysis of Biological Samples

Trace element analysis of biological samples can be useful for diagnostics of diseases caused by accumulation of some elements in the organism. The aim of this work was to evaluate the performance of Laser induced breakdown spectroscopy (LIBS) for the determination of elements present in human tissues. We have investigated samples of human liver and human spleen using pulsed Nd:YAG laser operating at 532 nm coupled with the Mechelle ME 5000 spectrometer covering range from 200 to 975 nm. Laser pulse caused ablation of samples followed by plasma generation. In the emitted spectra we could clearly detect Ca, Si, Mg, C, K, Fe, Cu, Na, Ti and Al spectral lines. In this work we present the comparison of intensity of iron spectral lines from spleens with diagnosed hereditary spherocytosis and hemosiderosis. This comparison indicates up to 4-times higher intensity of iron lines of spleen with hemosiderosis and 8-times higher intensity of iron lines of spleen with hereditary spherocytosis in comparison with the iron lines of reference spleen. LIBS showed to be a promising analytical method for these applications. Introduction Laser induced breakdown spectroscopy (LIBS) is a promising analytical method which has many advantages: simplicity, no sample preparation, rapid analysis, ability to sample gases, liquids and solids equally well. LIBS has manifold utilizations e.g. detection of versatile hazardous materials (Gottfried, 2007), chemical weapons (DeLucia, 2005), lead in paints (Marquardt, 1996) etc. Lately it is investigated in biological field too: hair tissue analysis (Corsi, 2003), elementar analysis of teeth (Samek, 2001), elementar composition of malignant and healthy animal tissues (Kumar, 2004) etc. Our experiments dealt with laser induced plasma on soft human tissues (liver, spleen). Our investigation studied the availability of LIBS technique to detect some interesting elements like iron, copper, aluminium, titanium in mentioned tissues. It could be useful for investigating human tissues with some pathologies characterised by cumulation of some elements. We have investigated iron contents in human spleens with diagnosed hereditary spherocytosis and hemosiderosis in comparison with healthy human spleen. Principle and experimental setup Principle of LIBS is based on the atomisation of investigated sample using high power laser pulse. Laser beem is focused on the sample surface and the breakdown is caused by high power of laser. Plasma is created above the surface of the sample and it causes dissociation and excitation of atoms and molecules from the sample. Emission spectrum is collected by fiber optics into the spectrometer. Recognition of atomic emission lines of output spectra provides species identification. For the identification of spectral lines we have used the national NIST database (Ralchenko, 2007). In our experiment we have used a frequency-doubled Nd3+:YAG laser (QUANTEL – Brilliant EaZy, maximal energy 165 mJ, maximal power 1,65 W, pulse duration 4 ns, wavelength 532 nm). Output beam was deviated in right by optical prism (Thorlabs, BK7) and focused using lens (Thorlabs, focal length 4 cm) on the sample surface. Emitted light of the ignited spark was collected with lens 189 WDS'09 Proceedings of Contributed Papers, Part III, 189–192, 2009. ISBN 978-80-7378-103-3 © MATFYZPRESS