Phosphorous Determination in Biochar-Based Fertilizers by Spark Discharge-Laser-Induced Breakdown Spectroscopy

Abstract

Biochar-based fertilizers are a new attractive alternative to P supplementation for crops, as they can gradually release the nutrient, avoiding losses and improving soil quality. In this regard, the evaluation of the P amount in biochar-based fertilizers is extremely important for their quality control. Analytical techniques that require sample solubilization are not very efficient for this task, as biochar is difficult to solubilize. Laser-induced breakdown spectroscopy (LIBS) is a promising technique to respond to this demand, as it enables a direct analysis of solid samples, avoiding the complicated process of sample solubilization. In this work, a novel method based on spark discharge (SD) coupled to LIBS was evaluated for P determination in biochar-based fertilizers prepared from three different biomasses. To overcome calibration problems in LIBS analysis, a matrix-matching procedure accomplished by the addition of eucalyptus biochar to calibration standards was used in experiments. This procedure minimized matrix effects and allowed us to achieve a satisfactory accuracy even when applied to similar but different matrices. Furthermore, the developed method is simple, fast, direct, does not generate post-analysis residues and appears appropriate for the quality control of sustainable biochar-based fertilizers and other biochar products.

Chemometric Approach Based on Explainable AI for Rapid Assessment of Macronutrients in Different Organic Fertilizers Using Fusion Spectra

“…This result was expected since Extratrees’ machine learning model is nonlinear and composed of many decision trees (Ensemble model). The previous study on fertilizer to determine PK was all based on simple linear regression or a simple machine learning model (SVR, PLSR) for both LIBS [ 12 , 28 , 29 ] and Vis-NIR [ 15 , 16 ]. However, the accuracy and applicability of these simple methods are often less than suitable since they focus only on the lines of interest and discard the spectral information provided by other lines [ 30 ].…”

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and materials

“…An example by Dib et al determined P in biochar-based fertilizers using spark induced LIBS. 72 Three types of biochar were prepared: ground eucalyptus leaves and branches, banana bre and peanut shells. Each type of biomass (3 g) was mixed with 100 mL of 270 mg L −1 P solution and then shaken for 24 h at 25 C. Aer pyrolysis, the materials were pressed to form pellets which were then analysed using a spark discharge (to improve sensitivity and stability) followed by LIBS analysis.…”

“…Analysis was achieved using ICP-MS with an assortment of internal standards introduced as a mixture on-line rather than being spiked into individual samples. The internal standards used were 45 Sc for those elements with a mass up to and including 59 Co, 72 Ge for the analytes 62 Ni to 95 Mo, 125 Te for 101 Ru to 137 Ba, 175 Lu for the analytes 189 Os to 197 Au and 209 Bi for analytes with a higher mass. Any polyatomic interferences were removed through the introduction of helium at a ow rate of 5 mL min −1 into the collision/reaction chamber.…”

“…An example by Dib et al determined P in biochar-based fertilizers using spark induced LIBS. 72 Three types of biochar were prepared: ground eucalyptus leaves and branches, banana fibre and peanut shells. Each type of biomass (3 g) was mixed with 100 mL of 270 mg L −1 P solution and then shaken for 24 h at 25 °C.…”

Phosphorus quantification in soil using LIBS assisted by laser-induced fluorescence

“…DP-LIBS provides increased sensitivity compared to LIBS with a 2-fold improvement in detection limit of selected elements [ 20 ]. Similarly, LIBS assisted by spark discharge (SD-LIBS) can provide improved results to conventional LIBS [ [21] , [22] , [23] ]. Furthermore, light elements such as sulphur, carbon, boron, and phosphorus have stronger lines in vacuum ultraviolet (VUV) range [ 24 ].…”