Hi Mark, I've used these...
https://proteinark.com/en/category/Proteus-X-Spinner-2.5-Centrifugal-Concentrator They have a hold-up volume of 25ul. I've had some success with them. The inverted orientation (pushing the membrane onto the protein rather than the protein onto the membrane) is a tad fiddly, but I've had good recovery down to low volumes. Dave -- Dr David C. Briggs CSci MRSB (he/him) Principal Laboratory Research Scientist (Signalling and Structural Biology Lab) and Co-chair, Crick Staff Consultative Forum The Francis Crick Institute London, UK Working hours: Mon-Fri 0900-1700 == about.me/david_briggs<https://about.me/david_briggs> | OrcID<https://orcid.org/0000-0002-9793-7339> | Google Scholar <https://scholar.google.co.uk/citations?user=DRKG5KwAAAAJ> == "Would it not be better if one could really 'see' whether molecules...were just as experiments suggested?" – Dorothy Hodgkin ________________________________ From: CCP4 bulletin board <[email protected]> on behalf of Mark J. van Raaij <[email protected]> Sent: 19 January 2026 14:15 To: [email protected] <[email protected]> Subject: [ccp4bb] Concentrating very small amounts of protein solution External Sender: Use caution. Dear All, the smallest centrifugal protein concentrators I know take sample volumes of 0.5 ml, like these: https://www.sigmaaldrich.com/ES/es/product/mm/ufc5010 (but other brands are also available). In theory you should be able to get to less than 40. In practice it is difficult. A problem is that, with a total protein amount of below 0.5 mg, a significant amount of it will stick to the plastic of the tubes and the filter, so it just becomes impossible to get very small volumes. I was wondering if there are other solutions available? Or efforts to miniaturise this? (apart from lyophilisation, which is not suitable for many proteins). Best wishes, Mark Mark van Raaij Dpto de Estructura de Macromoleculas, lab B5B Centro Nacional de Biotecnologia - CSIC calle Darwin 3 E-28049 Madrid, Spain tel. +34 91 585 4616 (internal 432092) ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 The Francis Crick Institute Limited is a registered charity in England and Wales no. 1140062 and a company registered in England and Wales no. 06885462, with its registered office at 1 Midland Road London NW1 1AT ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
