Sample splitting and extensive uniformity testing

Malvern Instruments has introduced a new batch of Quality Audit Standards (QAS).for confirming the performance of the company's range of particle size analyzers.

Malvern Instruments has introduced a new batch of Quality Audit Standards (QAS).for confirming the performance of the company's range of particle size analyzers.

This is believed to be the world's largest ever batch of particle sizing standards and will assure continuity of supply until the year 2020.

The new batch of standards was commissioned from independent specialist company Whitehouse Scientific (Chester, UK) who designed and produced a new high-capacity spinning riffler specifically for the task.

Starting with a master batch of 1000kg of glass beads with a size distribution from 13 to 130 microns, Whitehouse successfully split this bulk material through various riffling stages, into final lots of 2.5g and 0.25g single shot bottles.

The standard deviation obtained from a comprehensive series of bottle-to-bottle particle size measurements was 0.2 to 0.3%.

This means that the particle size distribution obtained from one bottle to another is equal to that obtained from repeat measurements of a single well-dispersed sample.

A key requirement of a Quality Audit Standard is that it should be available in sufficient quantity to allow its widespread adoption and use for the longest time possible, hence the need for a large batch of starting material.

Malvern's first batch of standards based on a 250kg master batch lasted for six years.

It is estimated that the new 1000kg master batch will provide standards until the year 2020 and beyond.

The slightly larger particle size distribution of the new standards brings the extra benefit that they can be dispersed in wet sample dispersion units without the need for surfactant.

Additionally, a lower dispersion pressure can be used for dry measurements.

A further refinement of the new standards is that they are now packed in shoulderless unbreakable bottles which empty completely without retaining any sample residues.

Malvern's Quality Audit Standards are supplied in packs of 10 one-shot bottles and come complete with measurement protocols, pass/fail criteria and Certificates of Conformance.

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