Particle size distribution (PSD) testing is a fundamental analytical technique used in numerous scientific and industrial fields, including pharmaceuticals, materials science, environmental science, and food technology. The distribution of particle sizes within a sample can significantly influence its physical and chemical properties, impacting processes such as dissolution, absorption, stability, and reactivity. This article provides an overview of the methods used in particle size distribution testing, their applications, and the importance of accurate and reliable measurements in laboratory analysis.
Methods of Particle Size Distribution Testing
Several techniques are available for particle size analysis, each with its own advantages and limitations. The choice of method depends on the nature of the sample, the size range of interest, and the required precision and accuracy.
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Laser Diffraction (LD):
- Principle: Laser diffraction measures particle size distribution by analyzing the pattern of light scattered by a sample when exposed to a laser beam. The scattering pattern is used to calculate the size distribution of the particles.
- Applications: Widely used in pharmaceuticals, ceramics, and food industries due to its broad measurement range (from sub-micron to millimeters) and rapid analysis time.
- Advantages: Non-destructive, requires minimal sample preparation, and provides quick and reproducible measurements.
- Limitations: Assumes spherical particles, which may lead to inaccuracies for irregularly shaped particles.
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Dynamic Light Scattering (DLS):
- Principle: DLS, also known as photon correlation spectroscopy, measures the fluctuations in light scattering due to the Brownian motion of particles in suspension. The fluctuation data is used to determine the particle size distribution.
- Applications: Commonly used for nanoparticles and colloidal suspensions in the pharmaceutical and cosmetic industries.
- Advantages: High sensitivity to small particles (nanometer range) and suitable for measuring particles in liquid suspensions.
- Limitations: Limited to small particles in dilute suspensions and may be affected by particle-particle interactions.
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Sieving:
- Principle: Sieving involves passing a sample through a series of sieves with progressively smaller mesh sizes to separate particles based on size.
- Applications: Traditional methods used in industries such as construction, mining, and agriculture for coarse particle size distribution analysis.
- Advantages: Simple, inexpensive, and suitable for large sample volumes.
- Limitations: Limited resolution for fine particles and time-consuming compared to modern techniques.
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Sedimentation:
- Principle: Sedimentation methods measure particle size distribution based on the settling velocity of particles in a liquid under the influence of gravity or centrifugal force.
- Applications: Used for fine particles in suspensions, especially in the ceramics and mineral processing industries.
- Advantages: Effective for a wide range of particle sizes and can handle concentrated suspensions.
- Limitations: Time-consuming and requires knowledge of the particle density and liquid properties.
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Image Analysis:
- Principle: Image analysis uses microscopy combined with software to capture images of particles and analyze their size and shape distribution.
- Applications: Useful for detailed morphological analysis in materials science, pharmaceuticals, and environmental studies.
- Advantages: Provides information on particle shape and size distribution and can analyze complex mixtures.
- Limitations: Requires significant sample preparation and may be influenced by operator bias.
Applications of Particle Size Distribution (PSD) Testing
Determination of particle size is essential in various fields due to its impact on material properties and performance:
- Pharmaceuticals: In drug development and manufacturing, PSD affects drug dissolution rates, bioavailability, and stability. Accurate PSD analysis ensures consistent drug efficacy and quality.
- Materials Science: In the production of ceramics, metals, and polymers, PSD influences mechanical properties, sintering behavior, and surface finish.
- Environmental Science: PSD analysis helps in understanding pollutant dispersion, sedimentation rates, and soil texture, which are critical for environmental monitoring and remediation.
- Food Technology: In the food industry, particle size distribution affects the texture, flavor release, and stability of products like emulsions, powders, and suspensions.
- Cosmetics: Particle size distribution influences the sensory properties, stability, and efficacy of cosmetic products such as creams, lotions, and powders.
Importance of Accurate Particle Size Analysis Testing
Accurately understanding the size of particles and how they are distributed is crucial for several reasons:
- Quality Control: Ensures consistency and quality of products, meeting regulatory standards and customer expectations.
- Process Optimization: Helps in optimizing manufacturing processes, improving efficiency, and reducing costs.
- Safety and Efficacy: In pharmaceuticals and cosmetics, accurate PSD ensures the safety and efficacy of products.
- Research and Development: Facilitates the development of new materials and formulations with desired properties.
Particle size analysis is a vital analytical technique in laboratory analysis across various industries. The choice of method depends on the specific requirements of the sample and the analysis. By providing critical information on particle size distribution, these techniques help ensure product quality, optimize processes and drive innovation in scientific research and industrial applications. Accurate and reliable particle size distribution analysis is essential for maintaining the high standards expected in modern laboratory testing environments.
Particle Size Distribution Test Requests
Below are a few of the test requests Contract Laboratory has received from companies or organizations needing laboratories to perform particle size distribution testing or analysis:
- Materials laboratory needed for ISO testing of cleaning abrasive to ISO 11126-10 Standard, Preparation of steel substrates before application of paints and related products—Specifications for non-metallic blast-cleaning abrasives 2. Cleaning and Consumption Rates 3. Recyclability and Dust Generation 4. Embedment Quantification 7. Surface Profile Depth and Peak Density 8. Particle Size Distribution (Sieve Analysis) 10. Abrasive Hardness 11. Abrasive Specific Gravity
- UK geology laboratory needed for clay testing for suitability for end uses such as clay bricks, tiles, ceramics, etc. Scope of testing to include: Stage 1 An initial gradient firing on each borehole material (10 samples) to determine the firing temperature/color related to each clay test piece after first milling to a suitable particle size range for clay brick manufacture. Stage 2 work scope The following tests will be carried out on the sample as received borehole material (10 samples): · Particle size distribution – to be determined using both the serigraph and dry sieving method, to cover the full-size range of particles from millimeters to microns.
- Geology Laboratory needed for ASTM testing: Analysis of rock salt (sodium chloride) based on requirements of ASTM D632. Chemical analyses will include sodium chloride purity (%NaCl) and moisture, but sodium ferrocyanide may also be requested. Physical analysis will entail a sieve analysis on the rock salt to determine the particle size distribution.
- LONG-TERM TESTING Geophysical Laboratory needed for Particle Analysis: Particle Size Distribution by Laser Diffraction of Quartz, Fly Ash, GGBS, etc. We require the Specific Surface area of the sample too, calculated by PSD analysis along with different D values and 1, 2, and 3 Sigma values as applicable and distribution results.
- Government Agency needs NABL-certified materials laboratory needed for Tests on silica filler (commonly used in rubber products) 1) CTAB 2) DBP Structure 3) Pour Volume Distribution 4) Pour Size Distribution 5) Zeta Potential 6) Particle Size Distribution 7) Purity
- OECD GLP Environmental Toxicology Laboratory is needed for Toxicology Testing Acute Oral Toxicity, AMES Test, Skin Corrosion, Skin Sensitization, In Vitro Mammalian Chromosomal Aberration Test (if AMES shows positive), In Vivo Mammalian Gene Mutation Test (if AMES shows positive); Eco-toxicological tests: Acute Fish Toxicity, Ready Biodegradability, Acute Daphnia Toxicity. and Physicochemical tests: Physical Status, Water Solubility, Melting/Freezing Point, Boiling Point, Vapor Pressure, Octanol/Water Partition Coefficient, Density, Particle Size Distribution;
- University researcher needs an environmental laboratory for soil analysis and water microbial analysis 1) soil physical particle size distribution test chemical, total carbon, minerals testing microbiological total fungal, bacterial and earthworm analysis 2) water microbiological analysis total fungal, bacterial and coliform determination
- and more!
Is your company or research organization in need of a laboratory to perform particle sizing? Let us help! Submit your specific test request. or contact us for more information
