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Enter the fascinating world of monodisperse particles.....

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What are Particle Size Standards good for ?

Particle size standards have mainly been designed for size calibration of particle sizing instruments, to validate and to check particle sizers regarding accuracy, size resolution, reproduceability and other performance characteristics.

Why is it necessary to calibrate ?

By many reasons e.g. dirtying of precipitating substances onto the inner glass walls of the sensor, by decreasing (laser)light intensity, etc. the signal intensities will change within time. But these signal intensities are the measure for the single particle diameters. So, by an adjustment called calibration a better fitting between signal intensity measured in mV and the particle diameter measured in nm or µm will be done. One needs at least six calibration points to receive a complete calibration curve. The values between the calibration points will be mathematically calculated by interpolation of the sizing instrument's software.
Calibration Curve
A complete calibration should be repeated with certified NIST traceable particle size standards periodically. Most of the particle sizers do not possess a linear calibration curve for the complete size range. Often there are several single linear ranges. This means that the fitting of the calibration curve will be better the more particle size standards will have been applied. In practice you have to make a compromise between increasing accuracy of the calibration curve and the number respectively the costs of the particle size standards.

Which calibration standards are needed ?

There are two types of particle size standards. Especially for particle counters   Calibration Standards of the LS Series   have been designed. For all other particle sizers which are not able to count particles but which are capable to determine particle sizes (only)   Calibration Standards of the HS Series   are the optimal choice.