Vincent Falco laments: > > > My problem is this:During some sorts I get ,what I will call a spurious extra > drop. To explain more,there are times I sort to polycarb filters.When all is > well I get a single spot which contains the desired cell population.When all > is supposed not well I get my desired single spot with cells and just about a > quarter of inch from the desired spot I observe a spurious spot,which does > not contain the desired cells. Hi, I've gottta have a stab at this one... Its a few years since I ran a sorter in my pevious life, but this sounds to me like a case of uncharged "satellite drops" merging with one of your charged drops. Someone will tell me if I'm off on a tangent :-) I'm guessing 3 drop sorts here. When the drops breakoff the joining neck forms a small "satellite droplet" , which depending upon phasing and frequency tends to merge either with the cell above or below it. (this is from deep memory, but there is a good discussion in Flow Cyt and cell sorting 2nd ed,... The Yellow one... by Myron Melamid (sp) and others) You can see all of this through the observation microscope, have a look to see which cell the satellite merges with when all is well, and I'll bet it goes the other way when you see the "doublet". I think you have an uncharged droplet merging with a charged cell, reducing the effective charge, causing less deflection and the appearance of the second spot. I think its a pressure/frequency thing, but check in the old yellow bible as its well covered. Best of luck -- Daryl Webb (dwebb@waite.adelaide.edu.au) Dept. of Plant Science, Waite Institute University of Adelaide, Glen Osmond S.A. 5064 Australia. Voice:61_8 8303 7426 Fax:61_8 8303 7102
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