Layered Ash Pellet Preparation for Foodstuff LIBS Analysis
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Solution Overview
Problem
Existing LIBS methods face challenges with sample preparation, particularly for foodstuffs, due to uneven surfaces, low signal-to-noise ratios, and matrix effects, which are exacerbated by the organic nature of food samples, making it difficult to form pellets for analysis.
Innovation Solution
A method involving ashing food samples to create an ash residue, forming it into a pellet with a support material, and compressing it to ensure a stable, undiluted surface for LIBS analysis, using a layered pellet structure with a support material to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foodstuff samples are ashed to generate ash residue, then sensitivity and accuracy of LIBS analysis is improved, but the amount of material available for analysis is reduced
Solution Approach 1:
The ash residue is segmented into multiple pellets, each containing a portion of the total ash. This allows the limited ash material to be distributed across several analysis samples, maximizing the use of the reduced material quantity while maintaining high sensitivity through the ashed state.
Solution Approach 2:
The invention creates composite pellets by combining ash residue with inert material (such as cellulose or plastic pellets). This composite structure increases the total volume and mass of the analysis sample while concentrating the inorganic analytes in the ash portion, thereby improving sensitivity without being limited by the small amount of pure ash available.
2Reliability
If ash residue is pressed into a pellet for LIBS analysis, then a stable surface for analysis is achieved, but the pellet thickness becomes too thin to endure LIBS measurement
Solution Approach 1:
By combining thin ash residue layers with thicker inert material pellets, the composite structure achieves sufficient overall thickness to endure LIBS measurement while maintaining a stable, flat surface. The inert material provides mechanical support without interfering with the analysis of the ash portion.
Solution Approach 2:
The invention transitions from analyzing a single thin ash layer to analyzing composite pellets where the ash is distributed in layers within a three-dimensional structure. This allows the laser to interact with ash surfaces at multiple depths and locations, effectively increasing the analysis volume while maintaining surface stability.
3Reliability
If support material is added to increase pellet thickness, then pellet stability is improved, but the signal-to-noise ratio decreases due to dilution
Solution Approach 1:
The composite pellet structure creates local concentration of analytes in the ash regions while the inert material provides structural support in other areas. During LIBS analysis, the laser preferentially ablates and analyzes the ash portions where the inorganic signals are concentrated, maintaining high signal-to-noise ratio despite the presence of inert material.
Solution Approach 2:
The invention uses an excessive amount of inert material to ensure adequate pellet thickness and stability, but relies on the fact that LIBS analysis only partially interacts with the inert material. The laser parameters and analysis method are optimized to focus on the ash portions, effectively ignoring the excess inert material while benefiting from its structural support.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method improves the sensitivity and accuracy of LIBS analysis by concentrating inorganic materials and reducing matrix effects, allowing for effective analysis of foodstuffs with complex organic matrices.
Implementation Method 1
LIBS is an atomic emission spectroscopy technique according to which a high powered laser beam pulse is focused onto a portion of a sample to produce a plasma. As the plasma cools, eventually the electrons return to their ground states. In the process, electromagnetic radiation is generated with wavelengths that are unique to the specific elements comprising the sample.
Implementation Method 2
Ashing the sample in order to improve sensitivity and reduce matrix effects of the LIBS analysis of botanical, agronomic and industrial samples has been proposed. Here samples were ashed by heating to a sufficiently high temperature and for a sufficiently long time in order for them to completely oxidise and leave relatively concentrated inorganic ash residues.
Data Source
AI summary
A method of analysing a foodstuff sample using laser-induced breakdown spectroscopy, comprises: ashing the foodstuff sample to generate an ash residue; and forming the ash residue into a layered pellet based on: loading at least the portion of the ash residue into a die, loading a support material into the die as a layer covering a second surface of the portion of the ash residue subsequently to loading at least the portion of the ash residue into the die, and compressing the portion of the ash residue and the support material in the die to form the layered pellet, such that a first surface of the portion of the ash residue at least partially defines the first surface of the layered pellet and the portion of the ash residue is undiluted by the support material at least at the first surface of the portion of the ash residue.