Dead time

From: Dr S Sreckovic, Pathology & Microbiology (Sasa.Sreckovic@bristol.ac.uk)
Date: Fri Apr 23 1999 - 11:45:55 EST


Hello fellow flow-ers,

I am operating FACSVantage SE at the University of Bristol and I have 
some really practical questions that I hope someone is going to give 
two pence for.

1. Does anyone have experience in using FITC, PE, QuantumRed, and 
PE-CY7 - all from 488 nm, in the same time on a Vantage. Is DM 710 SP 
(before FL1, FL2 and FL-3 and reflecting to FL-4) sufficient or should 
I also need band-pass filter in front of FL-4 used for detection of 
PE-Cy7? I have FL-6 installed from recently so if I use FL-6 for PE-Cy7 
detection I can even compensate between PE-Cy5 and PE-Cy7. 

2. I was sorting (believe it or not) only on FSC and SSC for one of my 
researchers to sort pure (and untouched) granulocytes apart from few 
lymphocytes and plenty of RBCs. It was a low-speed sort on 11 PSI, 
with DDF - 26 kHZ and 2000-2500 events/sec. ND filter was out and FSC 
set to log in order to detect RBCs and exclude them from sorting.
In this way I had more then 40% aborts and I assumed those are mainly 
force-aborts so I increased dead time from original 7.5 and get lowest 
abort rate on 13.5 but still more then 20%. Finally I had to put ND 
filter in and lose some of RBCs from detection in order to get less 
then 10 % abort rate. I thought that FSC amplification is going to 
increase only peak of the pulse but not a time of its detection also, 
having in mind force-aborts. I would appreciate any thoughts and I am 
aware that the best thing is to lyse RBCs but I must comply with 
researcher's aim.

3. I am experiencing big fluorescence loss with TurboSort and more 
then 10000 events/sec especially on FL-3. Anyone else?

Thanks everyone.

----------------------
Dr Sasha Sreckovic
Dept Path & Micro
University of Bristol
University Walk
Bristol, BS8 1TD, UK
Sasa.Sreckovic@bristol.ac.uk
0117-928-8606



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