Granularity testingThe accuracy is influenced by multiple factors such as method principles, instrument performance, sample characteristics, and operating standards. The following is a systematic explanation from four aspects: accuracy sources, influencing factors, improvement methods, and comparison of accuracy between typical methods:

　　Granularity testingThe core source of accuracy:

Limitations of methodological principles

Laser diffraction method: Based on the Mie scattering theory, assuming that the particles are spherical and uniformly dispersed. For non spherical particles (such as fibers, sheet-like particles) or widely distributed samples, there may be deviations between the theoretical model and reality, leading to a decrease in accuracy.

Dynamic Light Scattering (DLS) method: Depending on the Brownian motion of particles, multiple scattering is prone to occur for large particles (>1 μ m) or high concentration samples, which affects the accuracy of the results.

Image analysis method: relies on the clarity of particle images and algorithm recognition ability, with limited recognition accuracy for overlapping or transparent particles.

Differences in Instrument Performance

Resolution: The optical system of instruments such as the Malvern Mastersizer 3000 has a higher resolution and can distinguish particles that are closer in size; Low end instruments may combine similar particle sizes for statistical analysis.

Repeatability: Precision instruments (such as RSD<1%) have better repeatability than ordinary instruments (RSD>3%), especially more sensitive to small particle size changes.

Detection range: Some instruments (such as resistance method) have higher accuracy for specific particle size ranges (such as 0.4-1200 μ m), and the error increases when the range is exceeded.

Interference of sample characteristics

Agglomeration: Particle agglomeration can lead to larger measurement values and significantly reduce the accuracy of samples with poor dispersion.

Density and shape: High density particles settle quickly and may be mistaken for large particle sizes; There is an error in the calculation of the equivalent spherical diameter of non spherical particles.

Refractive index matching: Laser diffraction method requires inputting the refractive index of particles and dispersed media. If the parameters do not match, the result deviation can reach 10% -30%.