Response to article on mass photometer stage alignment (J Pharm Sci, Nov 2022)
In the article Critical Calibration of Mass Photometry for Higher-Mass Samples Such as Adeno-Associated Virus Vectors (published this month in the Journal of Pharmaceutical Sciences ), the authors describe an issue they encountered with their Refeyn OneMP Mass Photometer. When using it to analyze samples containing high-mass particles including AAVs, they noticed additional, unexpected peaks in the mass distribution that were confirmed to be an artifact. The authors then determined that these artifacts were the result of improper stage alignment and describe a stage calibration method, recommending it be used to check mass photometer performance.
At Refeyn, we stand by the accuracy and reliability of our instruments, so we would first like to sincerely apologize to the authors for the problem they experienced. Enabling our customers to succeed is one of our core ambitions, and we regret that we failed to achieve it in this case. In our view, the authors’ identification and interpretation of the problem are all completely correct, as is the way they solved it. Stage flatness is a known critical parameter for mass photometry performance and we put a lot of effort into optimizing it for all our instruments.
Any OneMP user with concerns should please contact the Refeyn service team, we are very happy to assess the state of the instrument and address any concerns – but we would prefer users not attempt to address these issues on their own as the stage assemblies are sensitive to damage if handled incorrectly.
The stage assembly of a TwoMP or SamuxMP is different from that of the OneMP. These stages, which should not be disassembled, inherently correct stage flatness deviations – therefore we strongly advise all users of TwoMPs or SamuxMPs not to change anything on those instruments.
As always, if you would like further information about this issue or have any other questions or concerns about our products, please do not hesitate to contact us.
 K. Takeda, M. Noda, T. Maruno, S. Uchiyama. Critical Calibration of Mass Photometry for Higher-Mass Samples Such as Adeno-Associated Virus Vectors. Journal of Pharmaceutical Sciences. 2022. https://doi.org/10.1016/j.xphs.2022.10.025.