We are asked on a regular basis, how is my Malvern Mastersizer calibrated ? Or how do I know my Malvern Mastersizer measures correctly ?
First of all laser diffraction particle size analysers like the Malvern Mastersizer series works on first principals of physics which simply means they do not require calibration in the tradional sense (a set of standards with a response curve ). The instrument is calibrated during manufacture and after that we simply confirm it is operating according to factory specifications using certain standards.
For day to day verification of the instrument Malvern Instruments provides a set of Quality Assurance standards which is a portion of glass beads that is tested according to a specific protocol. These standards meets the requirements of ISO 13320 in terms of density and polidispersity as it is a "realworld" sample. The standards are provided with control limmits to confirm the corect operation of your instrument. You do not need to test a standard of the same size as your typical sample as the glass bead standard generates a response over the majority of the detectors of the instrument proving that they all work correctly.
Another level of verification is performed by our service engineers when they test a number of latex reference standards with the customer's instrument after a routine service. The latex verification proves the absolute accuracy of the customer's instrument .
So next time someone asks if your Malvern instrument measures correctly run a QAS glassbead transfer standard !