What is particle size distribution and why is it important?
Particle size analysis , or the study of particle size distribution, is a crucial step in materials analysis. It allows us to determine the size and distribution of particles in a given sample, whether solid or liquid. Depending on the nature of the material, this analysis can be performed on powders, sands, suspensions, or emulsions. The main objective is to optimize the physical and chemical properties of the final products, such as fluidity, texture, and reactivity.
Particle size analysis is used in many sectors, from the food industry, where it ensures food texture, to the pharmaceutical industry, where it guarantees the uniform distribution of medications. In these sectors, precise particle size often translates to higher quality, increased productivity, and compliance with strict regulatory standards.
How is particle size measured?
There are several methods for measuring particle size. Sieving is one of the oldest and involves passing a sample through a series of sieves of decreasing sizes. While effective for large particles, this technique is limited in terms of accuracy and is not suitable for fine particles.
Laser particle size analysis, on the other hand, offers significantly greater precision. It allows for the measurement of particle sizes ranging from 0.05 µm to 900 µm using the principle of light diffraction. This ability to analyze both very small and large particles makes it a preferred method in many industrial sectors.
In addition, YesWeLab offers an analysis of sedimentation dynamics adapted to suspensions and sediments.
How does laser diffraction particle size analysis work?
The principle of laser particle size analysis is based on the diffraction of light. When a laser beam passes through a sample containing dispersed particles, these particles diffract the light. Depending on their size, the particles produce diffraction fringes at different angles. Large particles generate diffraction at small angles, while small particles diffract at larger angles.
The data obtained are then interpreted using mathematical models such as Mie theory, which takes into account the optical properties of particles, or Fraunhofer theory, used for larger particles. These models allow the particle size distribution to be reconstructed as a semi-logarithmic curve, representing the volumetric distribution of particles as a function of their size.
The speed of this method is one of its main advantages. In less than a minute, it is possible to obtain a precise measurement of particle size, which facilitates real-time control of industrial processes.
How does a particle size analyzer work?
Laser particle size analyzers are sophisticated devices capable of measuring particle size in real time, whether the particles are suspended in a liquid or in powder form. Take, for example, the MASTERSIZER 2000 from Malvern Instruments, a device commonly used in industry.
This instrument uses a focused laser to pass through a dispersed sample. The particles in the beam diffract the light, which is then captured by an array of detectors positioned at different angles. The collected data is subsequently processed by a microcontroller that calculates the particle size distribution.
Depending on the sample to be analyzed, the instrument can be configured to operate in dry mode (powders) or wet mode (suspensions). For these measurements, grain size measurement provides a precise solution for industrial powders and suspensions. For example, the SCIROCCO 2000 can measure powders ranging in size from 200 nm to 2 mm, while the HYDRO 2000SM is suitable for suspensions of particles from 20 nm to 2 mm.
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How to determine the grain size of a soil?
Soil particle size distribution is a crucial parameter in agriculture and geotechnics, as it influences soil permeability, water retention capacity, and mechanical stability. Several methods exist for determining soil particle size distribution, the most common being sieving for coarse particles. However, for finer particles, laser diffraction is often preferred due to its precision.
Laser diffraction analysis allows us to determine the distribution of different particle size fractions in a soil, whether it's sand, silt, or clay. This then allows us to adapt agricultural or construction practices according to the soil type. For example, a soil containing many fine particles, such as clay, will have low permeability and retain water longer, which influences crops or infrastructure built on that soil.
Scientific data: molecular analysis within the framework of laser granulometry
In particle size analysis, rigorous scientific methods are implemented to guarantee the accuracy of the results. A concrete example is the use of HS-GC-MS screening (gas chromatography and mass spectrometry) for the analysis of volatile compounds associated with the particles.
The process begins with the collection of samples in airtight and inert vials to prevent any contamination. Once the samples are collected, they are analyzed to quantify volatile compounds, with a limit of quantification (LOQ) ranging from 0.1 to 10 mg/L depending on the compound.
This method is often used in laboratories to ensure that particles, even at very low concentrations, are correctly identified and quantified. It is an essential process in many sectors, such as the chemical and pharmaceutical industries, to ensure that products meet the strictest quality standards.
These results can be complemented by a particle size analysis d10, d50, d90 for a precise quantitative characterization.
Applications of laser particle size analysis in industry
Laser particle size analysis has numerous applications across a wide range of industries. Here are a few concrete examples:
1. Pharmaceutical industry:
In the pharmaceutical sector, ensuring uniform particle distribution in medications is crucial, as it directly influences their bioavailability. Laser particle size analyzers allow for precise control of particle size in tablets, powders, and suspensions, thereby guaranteeing their therapeutic efficacy.
2. Chemical industry:
Polymers, pigments, and catalysts used in the chemical industry must have a homogeneous particle size to optimize their reactivity and stability. Laser particle size analysis allows for real-time monitoring of particle size distribution and ensures consistent product quality. For comprehensive characterization, these measurements can be combined with rheological analysis of the formulations.
3. Food industry:
In the food industry, particle size directly influences the texture and consistency of food. For example, the particle size distribution of ingredients like flour or sugar is essential for obtaining products of consistent quality. Laser particle size analysis allows for the analysis of these powders and the adjustment of production processes to guarantee the quality of finished products.
4. Cosmetics industry:
Emulsions and creams used in cosmetics require a precise particle distribution to ensure their stability and efficacy. Laser granulometry allows for the measurement of particle size in these formulations, optimizing their texture, absorption, and shelf life.
Why is laser particle size analysis an essential tool in the laboratory?
Laser particle size analysis has become a standard tool in analytical laboratories for several reasons. First, it complies with ISO 13320 , the standard governing the use of laser particle size analyzers. This standard ensures that analyses performed with this technology are accurate and reliable, which is essential for meeting the requirements of regulated industries, such as food and pharmaceuticals.
Laboratories also benefit from the speed and reliability of laser particle size analysis. Measurements can be taken in seconds, allowing for the processing of a large number of samples per day. Furthermore, the technology offers excellent reproducibility, ensuring consistent results, even with different samples.
Conclusion
Laser particle size analysis is an essential technique in many industrial sectors. It allows for the rapid and precise measurement of particle size, thereby optimizing manufacturing processes and ensuring product quality. Whether in the pharmaceutical, chemical, or food industries, it has become an indispensable standard for ensuring quality control and product conformity.
