For subatomic particles, see particle physics. This is the principle used for SALD-HC Series High-Concentration Sample Measurement System.This article is about particulate solids. There is also another approach to shorten the optical path length to avoid the influence of multiple scattering instead of adjusting the particle concentration. Of the combinations shown in Table 1, it will often be fairly difficult to adjust the particle concentration of the "possible" items. If the particle density is higher than the liquid medium density, separating the particles from the liquid by a centrifuge and discarding the supernatant liquid may be a viable solution. However, measures need to be devised if the concentration is lower than the appropriate range. If the particle concentration is higher than the appropriate range, it can be adjusted to an appropriate level by diluting the sample with liquid medium. When solid particles are dispersed in gas (in air), the particle concentration can be also adjusted by altering the injection nozzle or compressed air pressure.Īnd, when measuring liquid particles in a liquid, the particles are already dispersed in liquid. When solid particles are dispersed in a liquid and measured, particles can be added or liquid (liquid medium) can be added to adjust the particle concentration. This range is several tens of ppm to about 100 ppm (% by weight) when a regular flow cell or batch cell is used. This will cause the relationship between particle size and the diffracted/scattered light intensity distribution pattern to break down and prevent measurement from being carried out accurately.įor this reason, the particle concentration must be adjusted to an appropriate range for accurate measurement. However, if the particle amount is increased to obtain sufficient intensity and particle concentration becomes too high, then multiple scattering will occur. When particles become smaller, the intensity of diffracted/scattered light per single particle rapidly weakens proportionately to the power of six of the particle size. Particle concentration is an important measurement condition on a laser diffraction particle size analyzer. However, when a sample in a state where particles originally exist in a medium is to be measured, it is sometimes rather difficult to obtain just a "medium that does not contain particles." In the case of a liquid medium, a liquid must sometimes be prepared exclusively for blank measurement by using a filter to remove the particles.Īnd, when particles contained in film are to be measured, this means that measurement will be possible only if a film made of the same material not containing particles is available.ĥ) The particle concentration in the medium must be appropriate or it must be able to be adjusted to an appropriate level. In the case of dry measurement, too, whereby solid particles are injected and dispersed in air by compressed air and then measured, this is no problem since blank measurement is possible with nothing injected in air. When solid particles are dispersed in a liquid for measurement, that liquid should be used for performing blank measurement, so the importance of this condition is hardly perceived. The purpose of "blank measurement" is to ascertain the signal components of light emitted from all elements other than the particles to be measured, and subtract these components as the background level. 4) A medium that does not contain particles must be prepared (since it is used for blank measurement).
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