Malvern introduces the worlds largest ever batch of particle sizing Quality Audit Standards.

One of the most desirable features of a Quality Audit Standard is that it should be available in sufficient quantity to be adopted and used on the widest possible basis for the longest possible time.

After six years of successful operation, stocks of Malvern's QAS2001, QAS2002, QAS2003 and QAS2006 based on a master batch of 250KG of material have been replaced by a new series of standards based on a master batch of 1000Kg which is thought to be the largest quantity of a sizing standard ever produced.

The main benefit derived from creating such a large master batch is that supplies of the new standards are expected to last for at least 15 years.

Big Master Batch – high reproducibility.
The first job facing Whitehouse Scientific who produced the new Quality Audit Standard for Malvern Instruments was to ensure that the extremely high quality of the sample splitting obtained from the first batch of 250KG could be maintained or even improved on a master batch of 1000KG and, to help to do this, a new high capacity spinning riffler was designed and produced.

To assess the uniformity of the samples obtained from the new riffler, Malvern Instruments measured more than 100 samples drawn from 5 of the 40 separate sampling streams of the process.

The results of this testing (see fig 1 below) have shown that the reproducibility between samples is equivalent to the repeatability to be expected from repeat measurements of a single well dispersed sample.

Fig 1: 321 repeat measurements of QAS3002 in a single sample dispersion unit on the same optical bench show the bottle-to-bottle uniformity to expected from the new 1000Kg batch of of Quality Audit Standard.

The new Standards

QAS3001B 0.4g
Suitable for MS1, DIF2021, Hydro 2000S, Hydro 2000SM small volume sample dispersion units.
Replaces QAS2001 0.25g

QAS3002 2.5g
Suitable for the following wet sample dispersion units:
MS15, DIF2012, Hydro 2000G, Hydro 2000M, Hydro 2000MU.
Also suitable for the Autosampler 2000 as well as Scirocco 2000, EDA2000, EDA2001, MAM2460 and MAM2461 dry powder feeders
Replaces QAS2002 and QAS2003

QAS3004
Suitable for the Hydro 2000 µP.
Replaces QAS2005

What’s different about the new standard?

Supplies will last for 15 to 20 years
The new standard is based on a master batch of 1000KG of glass beads in order to assure continuity of supply.

Larger Particle size distribution
The d10, d50 and d 90 of the new material are 37.55, 63.14 and 92.03 respectively. This is a slightly larger size distribution than the earlier Quality Audit Standard. This size shift has reduced the fines fraction and has allowed us to reduce the dispersion pressure for dry measurements.

Bottle-to-bottle reproducibility is as good as repeat measurements of a single sample.
The relative standard deviation obtained from performing 321 repeat measurements during the characterization process necessary prior to launch of the new material is between 0.2 and 0.3%. This is as good as can be obtained from repeat measurements of a single well-dispersed sample. This means that out-of-specification results are reliably indicative of variations in system performance.

The calculation model used is now Single Mode for Mastersizer 2000 sample dispersion units (Monomodal for Legacy Mastersizer units).
The single mode analysis has been used to characterize the new standard since this gives improved sensitivity to out-of-specification results as well as providing a good fit to the distribution of the material.

New bottles give improved safety and ease of use
The bottles are now plastic and have straight sides to help the sample to be completely emptied without tapping or revolving the bottle.

FAQs

Can we continue to use QAS2002, QAS2003, QAS2005 and QAS2006?
Of course. The Performance Verification Specification which has been revised to give instructions for the use of the new standard continues to include instructions for the use of the batch one standards and will continue to do so for the foreseeable future.

QAS2003 for the dry powder feeders was a 5g sample. QAS3002 is only 2.5g. Is this sufficient for testing a dry powder feeder?
Extensive testing of QAS3002 on all the dry powder feeders has shown that a 2.5g sample gives just as reproducible results as a 5g sample.

Have the prices of the new standards changed?
No. The prices have been held unchanged.