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An Interlaboratory Study of Potential Visible Protein-Like Particle Standards



Srivalli Telikepalli, Michael J. Carrier, Dean C. Ripple


Visible protein-like particle standards can improve visual inspection and/or appearance testing practices used in the biotechnology industry. It will improve assay performance resulting in better alignment and more standardized training among different companies. The National Institute of Standards and Technology (NIST) has conducted an interlaboratory study to test whether the standards under development mimic typical proteinaceous particles found in biotherapeutics and if they can be implemented during the visual inspection process. Fourteen organizations from industry and government have participated. A total of 20 labs from these 14 organizations participated with analysts from 6 formulation, 7 analytical, 4 QC, and 3 manufacturing labs. The circulated samples consisted of abraded ethylene tetrafluoroethylene (ETFE) particles or photolithographic particles (SU-8). The results of this study are qualitative and display some variability among organizations and within labs. In general, the polydisperse ETFE particle suspension containing particles enriched in greater than 150 µm in size, were rated more favorably than the photolithographic particles by formulation and analytical scientists; the largest monodisperse photolithographic particles (approximately 300 µm in size) were favored equally by all scientists. Solution modifications to increase the settling rate or to alter optical properties of the ETFE particles to be more translucent yielded lower ratings by the analysts. Both particle types received mixed ratings for their usability and for their ability to be used for training purposes. Industry feedback from this work will assist NIST in developing reference material(s) for visible protein-like particles.
AAPS PharmSciTech


Telikepalli, S. , Carrier, M. and Ripple, D. (2022), An Interlaboratory Study of Potential Visible Protein-Like Particle Standards, AAPS PharmSciTech, [online], (Accessed June 13, 2024)


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Created November 1, 2022, Updated March 2, 2023