Quantification of Elements in Cow Fur by Laser-Induced Breakdown Spectroscopy
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Journal of Applied Spectroscopy, Vol. 87, No. 4, September, 2020 (Russian Original Vol. 87, No. 4, July–August, 2020)
QUANTIFICATION OF ELEMENTS IN COW FUR BY LASER-INDUCED BREAKDOWN SPECTROSCOPY I. Cherni,a,b S. Hamzaoui,b* and N. Jaïdaneb
UDC 621.375.826;543.42;533.9
The purpose of this work is to report an analytical procedure to prove the validity of the hypothesis of the representativeness of the mass vaporized in the plasma plume of the studied sample. To achieve that, we used the laser-induced breakdown spectroscopy (LIBS) technique to analyze some minerals and trace elements in cow tail hair. First, hair samples were dissolved in nitric acid; then the solutions were analyzed by an atomic absorption spectrometer. Ca, Mg, and Na mass concentrations were determined for the 25 hair samples. Finally, a small amount of hair from every strand was cut in very small pieces and mixed with potassium bromide to make 12-mm diameter pellets. The laser was focused on the pellet surfaces, and the intensities of the emission lines of the studied elements were related to their absolute mass concentrations already measured. Experimental conditions were chosen to guarantee the reproducibility of ablations and to minimize the fluctuations of the ablated mass. In addition, local thermodynamic equilibrium was verified to prove the possibility of use of the theoretical model to obtain the variation of the emission line intensity as a function of the species concentration in the plasma plume. Keywords: laser-induced breakdown spectroscopy, wool, representativeness, calcium, sodium, magnesium. Introduction. Many authors believe that hair analysis can be a complement to the conventional analysis of blood and urine [1, 2]. In fact, hair has several advantageous properties that make it a potential material of choice for a mineral analysis such as simple and noninvasive sampling and easy and inexpensive transport and storage [3, 4] compared to traditional biological matrices (urine or blood). Hair provides historical data on minerals and trace element levels in the body as well as nutritional status over a long period [5, 6]. It is considered to be a reliable indicator of the effects of toxic metals on human health [7, 8]. In fact, hair concentrations of minerals and trace elements are stable because of their inert and homogeneous appearance [9]. For these reasons, hair has been the subject of frequent researches for more than a quarter of a century [10, 11], and several techniques have been used to determine the concentrations of minerals and trace elements, such as X-ray emission spectrometry [12], flame atomic absorption spectrometry (FAAS) [13], cold vapor atomic absorption spectrometry (CV-AAS) [14, 15], and the atomic fluorescence spectrometry (AFS) [16]. However, these methods present some disadvantages; the pretreatment of the samples can be expensive. They can also take a lot of time and require the use of damaging chemicals [17, 18]. For these reasons, many authors opted for the use of laser induced breakdown spectroscopy (
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