What are the requirements as a particle reference material?

The verification and calibration of the particle size analyzer requires the use of particle certified reference materials (CRM). Different from general reference materials, CRM has certain regulations after fixed value, and the fixed value data is publicly released. Our country has certain regulations on the setting of primary CRM, which must adopt: ① absolute measurement method; ② multiple laboratories use accurate and reliable methods to collaboratively set values; ③ two or more different principles, accurate and reliable method. For particle reference materials, the current domestically recognized absolute measurement method is the microscopy method, and its scale can be traced back to the length standard. Usually the scale scale is 10um, and the current minimum has reached 416nm.

In addition to having an accurate value, a good standard material also requires ① good material stability and stable particle size value within a certain period of time (such as 1 year); ② good monodispersity, that is, the smaller the coefficient of variation of the particle size distribution, the better. Usually, The dispersion of the first-grade standard material is ≤3%, and the dispersion of the second-grade standard material is between 3% and 8%; ③ The sphericity is good, and the circularity is required to reach 95%·98%.