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Construction and application of a cost-effective portable LIBS system in in-situ chemical analysis **

Abstract

Laser Induced Breakdown Spectroscopy (LIBS) is a chemical analysis technique using a laser. The advantages of LIBS include extremely fast measurement, broad elemental coverage, its applicability in many spheres and phases, e.g., gas, aqueous, and solid phases in a minimally destructive manner. This research aims to develop a cost-effective portable LIBS that can be mounted on a robot arm or in-situ for rapid but accurate chemical analyses. First, an LIBS system consisting of Nd:Yag 1064nm pulsed laser, a UV-IR spectrometer, and a computer for chemical composition analyses, is being constructed. The high intensity laser pulse (5 ~ 20nsec) interacting with a sample (liquid, solid, or gas) produces a plasma plume (over 100,000 K), and the photons from excited electrons are detected by a spectrometer and analyzed by a computer system. The LIBS system is utilized in the following two applications. The advantages of LIBS can be utilized in integrity monitoring of water filtration membranes by analyzing the quality of purified water and detecting any spike of contaminants real-time. A lab-scale membrane filtration system has been constructed to test the correlation between the detected contaminant levels and the cleaning cycle of membranes (backwashing and chemical cleaning). This will benefit the industry and research sector in optimizing membrane filtration processes. Another application of LIBS is to detect heavy metals in food. There are toxic elements present in tea leaves that may cause adverse health effect, e.g., chromium, bromine, cadmium, and manganese, and the intensities of emission spectra for pelletized tea grains from each brand, at different wavelengths, will be obtained to quantitatively determine the amount of each element in samples. Results will be validated by inductively coupled plasma mass spectroscopy. The result would provide insights on daily consumption limit of tea in order to avoid too much intake of toxic elements.

Acknowledgements

GGC School of Science and Technology

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