Why is repeatability so important?

The repeatability of multiple measurements is a significant indicator used to describe either the working status of a particle size analyzer or the validity of the measurement procedure. Good repeatability shows a good working status of the whole measurement system, including laser source, detectors, signal transmission system, control system, circulation and dispersion system, and software. It can also confirm that a good measurement procedure has been utilized for the sample measurement. 

In other words, the working status of the instrument is stable, the working environment is suitable for the operation of the instrument, and the instrument can be competent for measurement. Suppose that the repeatability is not ideal, a system inspection is necessary. In addition to the inspection of the abovementioned components and systems, the choosing of the working environment is essential as well. Environmental factors, including input voltage, sunlight, external vibration, and electromagnetic interference, affect the working status of the instrument. For a smooth operation, the instrument needs to be isolated from the above-mentioned external factors that may cause bad repeatability. 

Furthermore, a proper measurement procedure must be adopted that suits the sample to be measured in the correct solvent (wet measurement) or correct pressure (dry measurement). Other factors to be considered include the choice of admixture, choice of surfactant, measurement time, ultrasonication duration, and ultrasonication strength. For the measurement of nanoparticles, the zeta potentials in the chosen media need to be considered.

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