Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm

Zhang, Huijie; Chen, Yao; Bi, Zongjie; Che, Xiaohua; Tian, Zhaoshuo

doi:10.3390/photonics12060616

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Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm

by

Huijie Zhang

,

Yao Chen

,

Zongjie Bi

,

Xiaohua Che

and

Zhaoshuo Tian

^*

Institute of Marine Optoelectronic Equipment, Harbin Institute of Technology at Weihai, Weihai 264209, China

^*

Author to whom correspondence should be addressed.

Photonics 2025, 12(6), 616; https://doi.org/10.3390/photonics12060616

Submission received: 12 April 2025 / Revised: 5 June 2025 / Accepted: 11 June 2025 / Published: 16 June 2025

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Abstract

To enhance sensitivity in detecting phosphorus in water via laser-induced breakdown spectroscopy (LIBS), this study integrates liquid–solid conversion on graphite substrates with a PLS-SVR fusion algorithm. Optimized laser parameters (500 mJ, 13 pulses) improved plasma excitation and signal-to-noise ratios. The graphite substrate adsorbed phosphorus, converting liquid samples into a solid matrix to suppress matrix interference and intensify spectral lines (P I 213.6 nm and 214.9 nm), achieving detection limits of 0.09 mg/L and 0.23 mg/L, respectively. Calibration curves showed high accuracy (R² = 0.9936). In real-world testing, absolute errors were below 0.017 mg/L, with relative errors <12%, aligning closely with traditional ammonium molybdate spectrophotometry. The PLS-SVR algorithm boosted prediction accuracy through data enhancement and spectral feature extraction, reducing errors to 2.1% (0.625 mg/L) and 5.6% (2.5 mg/L). With rapid sample preparation (<10 min), this method offers an efficient, low-cost solution for in situ phosphorus monitoring, advancing LIBS from lab to field use and supporting precise eutrophication management.

Keywords: laser-induced breakdown spectroscopy; liquid-to-solid conversion; PLS-SVR fusion quantitative analysis algorithm; water quality monitoring; quantitative analysis

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MDPI and ACS Style

Zhang, H.; Chen, Y.; Bi, Z.; Che, X.; Tian, Z. Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm. Photonics 2025, 12, 616. https://doi.org/10.3390/photonics12060616

AMA Style

Zhang H, Chen Y, Bi Z, Che X, Tian Z. Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm. Photonics. 2025; 12(6):616. https://doi.org/10.3390/photonics12060616

Chicago/Turabian Style

Zhang, Huijie, Yao Chen, Zongjie Bi, Xiaohua Che, and Zhaoshuo Tian. 2025. "Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm" Photonics 12, no. 6: 616. https://doi.org/10.3390/photonics12060616

APA Style

Zhang, H., Chen, Y., Bi, Z., Che, X., & Tian, Z. (2025). Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm. Photonics, 12(6), 616. https://doi.org/10.3390/photonics12060616

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Detection of Phosphorus in Water by Laser-Induced Breakdown Spectroscopy Based on Liquid-Solid Transformation of Graphite Substrate Combined with PLS-SVR Fusion Quantitative Analysis Algorithm

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