Laser diffraction is a powerful technique for measuring particle size rapidly and with statistical significance. The particle size parameter is a critical indicator of process consistency and product quality in many industries. These two factors have led to widespread adoption of laser diffraction for quality control or quality assurance purposes. In the QC/QA environment, there may be additional requirements around user access and data integrity, in order to ensure the quality of the data itself is high and that this is recorded in an audit trail. The requirements for the most robust levels of data integrity are described in 21CFR Part 11. In this webinar I will discuss the issues involved with data integrity, using the Mastersizer 3000 as an example. This will include an overview of the Malvern security system, which provides user access control and 21CFR Part 11 compatible audit capability, as well as discussion of the application of 21CFR Part 11 to laser diffraction.