>Date: Mon, 16 Jun 1997 08:17:33 -0400 (EDT) >From: Matthew J Shaw <shawmj@battelle.org> >Subject: Viscosity Effects on FCM Analysis > > 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 Many years ago, I performed an experiment with a FACScan that sup- ports Matt's hypothesis that viscous fluids may not flow as readily through the flow cytometer. My "viscous solution" was detergent-solubilized nuclei from the Jurkat cell line, stained with propidium iodide. The stock solution was fairly concentrated, as I recall -- perhaps 10 million cells/ml. I did not have the means for measuring the viscosity of this solution. I tried this at full strength and at various dilutions. I weighed the tubes on an analytical balance, ran them on the FACScan for five minutes, and weighed them again. I used the low flow rate, which pumps 12 microliters/minute when the sample tube contains just plain water. Over the course of the five minutes, I watched the acquisition event rate in order to be sure that any drop that I might see in the *mass* flow rate (microliters/minute) was not the result of temporary clogs in the sample injection tube. I think that I did get such clogs at the higher cell concentrations. However, even at the lower concentrations, there was clearly a drop in the mass of liquid transferred, even when there were no hiccups detectable in the event rate. Hope that helps! - John Ladasky
This archive was generated by hypermail 2b29 : Wed Apr 03 2002 - 11:49:51 EST