Extended total number density compensation for uranium determination by laser-induced breakdown spectroscopy

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Materials Science

Background:

• Plasma property variations in laser-induced breakdown spectroscopy (LIBS) cause signal uncertainty and matrix effects.
• Accurate compensation for total number density variation is challenging due to unreliable spectroscopic parameters.
• Previous total number density compensation (TNDC) methods have limitations with complex samples.

Purpose of the Study:

• To introduce an extended total number density compensation (ETNDC) method for improved LIBS analysis.
• To reduce signal uncertainty and matrix effects in uranium determination using LIBS.
• To enhance the accuracy and robustness of LIBS for complex sample matrices.

Main Methods:

• Developed ETNDC by weighting spectral lines from major elements to reflect total number density variations.
• Incorporated temperature and electron density compensation into ETNDC weighting coefficients.
• Applied ETNDC as a pre-processing step for uranium determination in yellow cake samples using regression models.

Main Results:

• ETNDC significantly reduced the mean relative standard deviation (RSD) of U II 417.159 nm from 4.92% to 2.27%.
• The root mean square error of prediction (RMSEP) decreased from 4.81% to 1.93% with ETNDC.
• ETNDC demonstrated superior average performance and robustness across multiple validation sets and line combinations compared to baseline methods.

Conclusions:

• ETNDC is the first method to explicitly address temperature and electron density variations alongside total number density compensation.
• Inaccurate spectroscopic parameters are avoided by fitting related quantities using concentration information.
• ETNDC significantly improves signal repeatability and analytical performance for accurate uranium quantification via LIBS.