Qualitative and quantitative evaluation of blood cholesterol using laser plasma spectroscopy and calibration-based linea
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Qualitative and quantitative evaluation of blood cholesterol using laser plasma spectroscopy and calibration‑based linear discriminant analysis Farzaneh Ghazi‑Maghrebi1 · Hamidreza Shirvani‑Mahdavi1 · Seyede Zahra Shoursheini2 Received: 6 July 2020 / Accepted: 16 October 2020 / Published online: 2 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this paper, the cholesterol concentration of human blood serum is qualitatively and quantitatively scrutinized via laserinduced breakdown spectroscopy (LIBS) and discriminant function analysis (DFA). To achieve this goal, four normal standard samples with different concentrations of cholesterol and one pathological sample as a target, all from human blood serum, are prepared. Initially, the range of cholesterol concentration of the target compared to that of standard samples is determined using three bar charts related to the spectral intensities of cholesterol components. Then, in contrast to the common cases, the DFA is exploited to measure the cholesterol concentration of the target. First of all, three discriminant functions (DFs), their contributions in the discrimination, and groups’ centroid for all DFs are determined. Thereafter, for each DF, the cholesterol concentration of the samples is plotted against the centroid of the groups as a linear calibration diagram (LCD). Eventually, the cholesterol concentration of the target and its standard error of the mean (SEM) are calculated using the contributions obtained from LCDs by considering and exerting the discrimination percentages of DFs. Comparing the results with the values certified by the manufacturer about the target indicates strong performance of this approach in quantitative analyses.
1 Introduction In LIBS through which qualitative and quantitative elemental analysis are performed, a laser pulse with appropriate wavelength, energy, intensity, and pulse duration initially focuses on or in a sample. Owing to absorbing a part of the laser pulse energy, first, microablation occurs in the sample, and then, the ablated portion is dissociated to its constituent elements and ions [1–5]. After establishing a relative balance between positive ions and electrons, a very high temperature transient plasma is generated in the front of the sample. By passing time, any species in the plasma will successively be de-excited, which leads to its unique spectrum. Therefore, LIBS is a type of atomic emission spectroscopy having several advantages including little or no sample preparation, fast measurement time, wide wavelength bandwidth, * Hamidreza Shirvani‑Mahdavi [email protected] 1
Photonics Research Laboratory, Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran, Iran
Department of Physics, Alzahra University, Tehran, Iran
2
minimally invasive, and applicable to different phases of the sample [4–6]. In addition, it is used to identify different elements and determine their concentrations in various materials including soil [7–9], food [10–13], alloy
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