Rapid analysis of magnesium in infant formula powder using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was investigated to determine magnesium (Mg) content in infant formula powder. To predict Mg content in the range established by the Codex Alimentarius, a partial least squares regression (PLSR) model was developed using a calibration data set (n = 30) based on full cross-validation and validated using an independent validation data set (n = 21). The prediction model performance was evaluated using the regression coefficients of determination (R_cv ² = 0.94 and R_p ² = 0.85) with the root mean square errors on cross-validation and prediction (RMSECV = 60 mg kg⁻¹ and RMSEP = 80 mg kg⁻¹). The limit of detection (150 mg kg⁻¹) was also calculated. In addition, LIBS successfully predicted the Mg content distributed within a pellet. This study demonstrated that LIBS is suitable as a rapid reagent-free method for the quantification of Mg in powdered infant formula and can provide spatial information with acceptable accuracy.