Quantitative analysis of pH value in soil using laser-induced breakdown spectroscopy coupled with a multivariate...

Area of Science:

• Analytical Chemistry
• Soil Science
• Spectroscopy

Background:

• Accurate soil pH measurement is crucial for agriculture and environmental monitoring.
• Traditional methods for soil pH analysis can be time-consuming and labor-intensive.

Purpose of the Study:

• To develop a rapid, reliable, and accurate method for quantitative soil pH analysis.
• To evaluate the effectiveness of laser-induced breakdown spectroscopy (LIBS) for soil pH determination.

Main Methods:

• Utilized laser-induced breakdown spectroscopy (LIBS) for elemental analysis of soil samples.
• Employed multivariate regression models, including partial least-squares regression (PLSR) and least-squares support vector regression (LS-SVR).
• Focused on the emission line intensities of nine elements (C, Ca, Na, O, H, Mg, Al, Fe) to build predictive models.

Main Results:

• The PLSR model achieved correlation coefficients of 0.897 (calibration) and 0.906 (prediction).
• The LS-SVR model significantly improved accuracy, with correlation coefficients of 0.991 (calibration) and 0.987 (prediction).
• LS-SVR resulted in a prediction mean absolute error of 0.1 pH units and a root mean square error of 0.079.

Conclusions:

• LIBS coupled with LS-SVR is a highly accurate and reliable technique for rapid soil pH determination.
• This method offers a significant advancement over traditional soil pH analysis techniques.
• The developed approach minimizes matrix effects, ensuring robust pH measurements.