Re: Viscosity Effects on FCM Analysis

Ray Hicks (
Tue, 17 Jun 1997 11:15:52 +0100


Freyer-JP; Fillak-D; Jett-JH studied the effects of viscosity in a way in
Cytometry. 1989 Nov; 10(6): 803-6, they used xanthan gum to slow the
settling of cells prior to passing them through a cytometer. Xanthan is
thixotropic or pseudoplastic, so although it's thick at rest, it flows
easily under stress. How does your viscous medium behave?

Another problem that might occur before you reach the point that your
suspension won't go through the nozzle is that there may not be enough
stress from the sheath to bring about hydrodynamic focusing or stretching
of the core to produce the spatially constrained single file of cells that
we all know and love, you might get around this by upping the sheath
pressure (you might need to increase sheath viscosity to prevent

On that last point, has anyone studied the effects of sheath viscosity on
core stability (and sample cv's) at high flow rates?


ISSN: 0196-4763At 8:17 am -0400 16/6/97, Matthew J Shaw wrote:
> All,
> Does anyone have a good feel for the effects of higher viscosity
> fluids being analyzed via flow cytometric means? For example, the
> viscosity of water is 1 centipoise, and I assume that cells that are
> within water can be reliably analyzed. I believe that the viscosity
> of blood is perhaps 3 centipoise; again, I assume that cells within
> this matrix can be reliably analyzed. However, if the matrix is say
> 10 centipoise, there may be a problem with forcing the matrix through
> the FCM nozzle. Maybe a problem doesn't exist until the matrix is 100
> centipoise? Has anyone done a study like this on any flow cytometer,
> or have a good feel for this effect? What is the upper viscosity
> limit before any problems may occur? (I realize that one could dilute
> the sample with a low-viscosity liquid until the desired viscosity is
> reached - I'd rather not have to do that!) I would appreciate any help
> on this matter.
> Matt Shaw

Ray Hicks
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