[RASMB] Viscometer technology

[John Sumida]

Dear David,

 

Your post piqued my curiosity.  Please forgive my ignorance on the topic, but why is protein viscosity something one would be interested in?  And for those who make these types of measurements, what is the variability in protein viscosity?

 

Thank you all for your comments and responses, now and in the past.  This bulletin board has been a great learning tool.

 

Best regards,

John Sumida

University of Washington

 

From: RASMB [mailto:rasmb-bounces at list.rasmb.org] On Behalf Of David Hayes
Sent: Wednesday, June 03, 2015 5:23 AM
To: RASMB
Subject: [RASMB] Viscometer technology

 

Hi all (especially hoping Steve Harding is active),

 

I recently saw the Malvern viscosizer.  It is a capillary viscometer and taylor dispersion instrument.  (Taylor dispersion looks at the diffusion pattern of a small plug of sample in a capillary).  Because of the small volumes used, it could be useful for screening early limited supply proteins for viscosity problems.

 

Are there any general thoughts on the technology?

 

I remember Steve Harding telling us at BITC that you never use rolling ball viscometers on proteins:  the proteins stick to the ball.

Recently we found out here that the regular Anton Paar cone and plate rheometers sometimes need PS-80 in protein samples or the air water interface around the outside edge can predominate the viscosity measurements.

 

I did ask whether most samples just stick to the capillary and disappear or run anomalously, but the answer was they had a super coating so most things won’t stick.  This coating makes the capillary impossible to clean (so you buy more capillaries from Malvern).  And that the taylor dispersion fitting will tell you if and approximately how much the sample interacts with the capillary walls.

 

Kind Regards,

 

David Hayes

 

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