Autoconcentration facility for Mastersizer 2000 Autosampler optimizes particle sizing
Keywords: Malvern Instruments Ltd, Particles, Sizing
The new Autosampler unit for the Malvern Mastersizer 2000 features a sample autoconcentration facility, which reportedly ensures that the sample concentration is always optimal for a perfect size measurement.
Achieving optimal sample concentration in laser light based systems is vital to good particle size measurement. If the concentration is too low, the statistical significance of the results will be poor, whereas at too high a concentration, multiple scattering effects can lead to erroneous results.
According to Malvern, the Autosampler 2000's highly effective isokinetic sampling system ensures that even the broadest particle size distributions are correctly sampled without loss of either the coarse fraction or the fines.
The Autosampler delivers a standard 10ml "slug'' of sample dispersion to the sizer. If the resulting sample concentration is too high, the system is said to automatically calculate the number of dilution steps that must be carried out in the sample pot of the Autosampler in order to deliver a 10ml dose of suspension that will give the right final concentration. The Autosampler reportedly then carries out these dilution steps by removing a perfect 10ml sample from the pot and substituting a 10ml dose of clean dispersant, thoroughly mixing it each time. In this way, the concentration is progressively reduced while the original size distribution is preserved.
Once the correct number of dilution steps has been completed, the sample dispersion unit of the sizer is flushed and prepared to measure the sample at the correct concentration.
Malvern asserts that by using this technique it is possible to achieve accurate reduction of concentrations (expressed in terms of laser obscuration)from +50 per cent to 5 per cent. This reduces reliance on accuracy of sample loading by the operator and ensures absolute consistency of results.
Details available from: Malvern Instruments Ltd, Tel: +44 (0) 1684 892456;Fax: +44 (0) 1684 892789; E-mail: dipti.leinum@malvern.co.uk
