Particle Size Standards

MALVERN QUALITY AUDIT STANDARD

Analysts can easily check the performance of their Malvern particle size analyser dispersion units, with a low cost Quality Audit Standard (QAS). This comprises glass spheres polydispersed between 10 and 120 microns, packaged in ‘one-shot’ vials.

These standards completely fulfill the recommendations of ISO 13320. Comprehensive analysis has established confidence limits of 0.36% on the Dv50 of 48.28 microns. The single shot concept means that the entire contents of the vial are used for every measurement. Three vial sizes are available in order to obtain the correct level of obscuration for all models of dispersion unit.

QAS packs contain 10 one shot vials, each uniquely numbered to aid traceability. Median sizes of Dv10, Dv50 and Dv90 are documented.

WHITEHOUSE MIRROR STANDARDS

BACKGROUND

These standards were so named because they mirrored the size ranges of an official set of spherical reference standards that were being developed for the European Community (Community Bureau of Reference –BCR). The ‘Mirror’ Standards were made both to assess the performance of the analytical laboratories and to augment a limited supply of the official standards.

POLYDISPERSE GLASS MICROSPHERES

• Developed to support the official Community Bureau of Reference (BCR) particle metrology standards.
• Traceability through NIST, BCR and NPL standards.
• Calibration for any method of particle size analysis including laser diffraction.
• 7 standards covering the size range 0.1 - 2000µm.
• Produced as single-shot vials from 10mg – 10g.
• Priced to encourage regular calibration.

NEW 0.1 - 1µm Standard

This new standard has been introduced by popular demand resulting from an increased interest in the properties and performance of Nanoparticles or sub-micron powders. The soda-lime glass microspheres are supplied as dry powders in a 5ml pipetting bottle. To analyse, simply add water and place in an ultra-sonic bath for a few minutes, shake well and pipette the complete bottle into the particle size measurement instrument. The standard has been characterised by scanning electron-microscopy, pipette centrifuge and some of the latest laser sizing methods.

New Method for Calibrating Sieves

Sieve accuracy can now be checked "in house". This new method provides verification using microsphere standards. It is a simple weighing technique, which is both fast and low cost.

So now there is no excuse not to check the sieves that are used to check the product.

These sieve standards from Whitehouse Scientific cover every sieve between 20 and 3350 µm.

• Sieves do not need to be sent away for calibration.
• High speed – procedure completed in 2 minutes.
• Single-shot vials, removes operator sampling errors.
• Accurate to 1 µm for the smaller apertures sieves.
• Method analyses over 80% of the sieve surface.
• Traceable to international standards – NIST, NPL.

A simple but high precision method

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