Feasibility of low-power low-resolution laser-induced breakdown spectroscopy for quantification of Mg in fermented soybean pastes

This study explores the use of a cost-effective laser-induced breakdown spectroscopy (LIBS) instrument for analyzing magnesium (Mg) in fermented soybean pastes. Composed of soybeans and salts, these pastes are rich in proteins and minerals. A low-power diode-pumped solid-state laser and a miniature low-resolution spectrometer were used to analyze nine products, with Mg concentrations previously determined via inductively-coupled plasma optical emission spectroscopy. The LIBS spectra showed Mg II and Mg I emission peaks at 279.8 and 285.2 nm, respectively, used to create univariate calibration models. Additionally, a partial-least-squares regression (PLS-R) model showed superior accuracy. Mg concentrations correlated with the types of salts used. The study demonstrates the feasibility of using real products as calibration standards for LIBS, supported by other methods. The compact, low-cost LIBS instrument offers an alternative for quantitative mineral analysis and raw material identification in fermented soybean pastes.