研究目的
To predict calcium content in ready-to-feed infant formula using laser-induced breakdown spectroscopy (LIBS) for direct analysis of liquid food products.
研究成果
LIBS combined with multivariate analysis was successfully employed for quantifying the calcium content of RTF-IF samples. The PLSR model exhibited good fit and linearity, demonstrating the potential of LIBS as a real-time tool for mineral analysis in liquid foods, with advantages such as fast measurements, no need for reagents, and minimal sample preparation.
研究不足
The direct analysis of liquids with LIBS can be problematic due to effects such as splashing or formation of ripples on the liquid surface, which may hinder sensitivity and repeatability. The study also noted higher relative standard deviations for LIBS measurements compared to AAS.
1：Experimental Design and Method Selection:
The study employed a LIBS system coupled with a liquid sample chamber featuring a rotatory wheel to present the liquid as a thin film to the laser beam. Multivariate analysis with partial least squares regression (PLSR) was used to correlate LIBS spectral data to reference calcium contents.
2：Sample Selection and Data Sources:
Ready-to-feed infant formula (RTF-IF) and ready-to-feed follow-on formula (RTF-FOF) were used. Samples were prepared with varying calcium contents by mixing RTF-IF with calcium chloride or distilled water.
3：List of Experimental Equipment and Materials:
A LIBS-6 system with a 150 mJ Q-switched Nd:YAG laser, six spectrometers covering 181–904 nm, and a liquid chamber (SC-LQ2) with a rotatory wheel. Atomic absorption spectroscopy (AAS) was used for reference calcium content measurement.
4：Experimental Procedures and Operational Workflow:
Samples were measured by pouring approximately 40 mL into the liquid reservoir. Spectra were recorded at three different laser energy outputs (50, 100, and 150 mJ) with 200 consecutive laser shots per energy measurement.
5：Data Analysis Methods:
Univariate and multivariate data analysis were performed using R and the R package 'pls' for PLSR modelling. Spectral normalization against the H I spectral line at 656.29 nm was applied.
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