![]() ![]() The mean values for D10 and D90 must not deviate by more than 5% from the certified range of values. The response of a laser diffraction instrument meets the requirements, the mean value of D50 from at least three independent measurements is not more than 3% of the certified range of values of the certified reference material. Sample splitting techniques for example spinning riffler or the cone and quartering method may be applied. The sampling technique must be suitable for a sample of a suitable volume for the particle size measurement. However, in a dry measurement technique, a different set of samples is analyzed each time, which may result in variation. This results in precise repeat measurements. Precise results: In a wet measurement technique, the same sample dispersion gets analyzed multiple times as it repeatedly passes through the detector. Toxicity: Handling samples in the wet state makes control easier, reducing the risk of inhalation.įragile particles: Wet dispersion provides more gentle dispersion for fragile particles as compared to the dry technique. The wet measurement technique can be preferred due to the below reasons.Ĭohesive or fine particles: Cohesive or very fine particles below 20 μm can be difficult to disperse completely using dry techniques, however, the wet technique can help in achieving proper dispersion. The factors such as the natural state of the sample (free-flowing powder, crystalline, coarser, etc.), toxicity, solubility, dispensability, etc. The analyst has to make a decision on the appropriate measurement technique between dry and wet. Which one is the best method, Wet or Dry? The information must be documented about the sample preparation, dispersion condition, and cell type because the results depend on the particular instrument, optical model used, and data analysis program. The sample dispersion is measured according to the developed method. The detector data are saved in order to subtract them later from the data obtained with the sample.ĭ. The background signal must be below an appropriate threshold.Ĭ. After proper alignment of the optical part of the instrument, a blank measurement of the particle free dispersion medium must be performed using the same method as that used for the measurement of the sample.ī. Mostly, the dispersers use the energy of compressed gas or the differential pressure of a vacuum to disperse the particles into an aerosol blown through the measuring zone, into the inlet of a vacuum unit that collects the particles.Ī. Dry powders can also be converted into aerosols through the use of suitable dry powder dispersers that apply mechanical force for de-agglomeration or de-aggregation.Ĭ. A suitable sample quantity is taken to fill the hopper.ī. Generally, two types of PSD measurement methods are widely used, which are as below,Ī. Types of measurement used in the Laser Diffraction method: Mie’s theory needs knowledge of the optical properties, such as the refractive index of the measured sample, along with the dispersant. The particle size is described as a volume equivalent to the sphere model. Using the Mie theory of light scattering, angular scattering intensity data gets analyzed to calculate the size of the particles responsible for creating the scattering pattern. Large particles scatter light at small angles relative to the laser beam, and small particles scatter light at large angles”. ![]() “Laser diffraction measures the particle size distributions by measuring the angular variation in the intensity of light scattered as a laser beam passes through a dispersed particulate sample. Working Principle of the Laser Diffraction Method: Fast and can be executed on very small samples.Wide range application between 0.1 µm to 3000 µm.The laser diffraction method is one of the best techniques for PSD analysis because: The below techniques are used for particle size distribution (PSD) analysis We are going to discuss particle size distribution in this article. The PSD of a material may be significant for understanding its physical and chemical properties. Particle size analysis is a technique used to characterize how particles are distributed in a sample. Particle size distribution is the most important analysis because it is used widely in Pharmaceuticals (dissolution, manufacturing, and bioavailability), building materials, paints, coatings, food, and drink industries. ![]()
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