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Are Your Particles Charged?

NIST SRMs 1992 and 1993 Zeta Potential Measurement Standards

A picture of vials of SRM 1992 and SRM 1993

What: SRMs 1992 and 1993 are new standards developed in a partnership with the European Commission Joint Research Centre to address a critical need for traceability in the measurement of zeta potential by electrophoretic light scattering and electroacoustic methods. They consist of colloidal silica particles suspended in an aqueous borate buffer at pH 8.9. SRM 1992 has a nominal solids mass fraction of 0.15 % and is ideal for light scattering methods, whereas SRM 1993 has a mass fraction of 2.2 % and is appropriate for calibration of electroacoustic instruments.

Why: SRMs 1992 and 1993 are essential for verifying correct performance of instruments that measure the electrophoretic mobility or zeta potential of nanomaterials and colloidal particles dispersed in aqueous media.

Who: Zeta potential, a property associated with charged particles in solution, is the single most important predictor of colloidal stability and is considered an essential parameter for characterizing the environmental, health and safety attributes of nanomaterials. Zeta potential is important for a wide range of applications and employed across industrial, academic and government laboratories. Applications include drug delivery systems, antibiotic coatings, pigments, energy related products, environmental risk assessment, and more.

How: SRMs 1992 and 1993 are used as traceable references to assure the correct performance of instrumentation for measurement of electrophoretic mobility and zeta potential. SRM 1993 can be used to calibrate electroacoustic devices that measure zeta potential based on electrokinetic sonic amplitude or colloid vibration current.

Released December 21, 2020, Updated January 12, 2021