PMT-enhanced LIBS with precision time control for ultra-sensitive selenium detection in rice

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Agricultural Science

Background:

• Selenium (Se) intake is beneficial within a narrow concentration range.
• Accurate detection of Se in agricultural products is essential.
• Conventional laser-induced breakdown spectroscopy (LIBS) faces challenges in Se detection due to excitation and observation difficulties.

Purpose of the Study:

• To develop a rapid and accurate method for detecting selenium in agricultural products.
• To overcome the limitations of conventional LIBS for Se analysis.
• To improve the selective detection of Se signals and reduce interference.

Main Methods:

• Integration of a chopper with a photomultiplier tube (PMT) for precise signal timing.
• Utilizing delayed triggering to selectively capture plasma signals.
• Employing signal kurtosis analysis for non-delayed signals.
• Optimizing delay time to enhance the Se signal-to-interference ratio.

Main Results:

• The developed method selectively detects Se signals, minimizing interference from bremsstrahlung and other elements.
• Quantitative results showed significant improvement with R² of 0.991.
• High stability was achieved with an average relative standard deviation (ARSD) of 14.2%.
• Achieved a limit of detection (LOD) below 2 ppm for solid samples, a first for this technique.

Conclusions:

• The integrated chopper-PMT system offers a reliable and advanced method for selenium detection in agricultural products.
• This technique enhances signal selectivity and reduces interference, improving quantitative accuracy.
• The achieved low LOD provides a valuable tool for ensuring the quality of selenium-enriched foods.