Hello to all, It may be that this is a trivial question: What is the effect of combining log and lin amplification, e.g. for FITC and 7-AAD, on hardware compensation on instruments using analog log amplifiers? My guess is that the setup probably only has been designed and validated for log to log compensation. Probably someone can comment on where the compensation is actually performed on such instruments (before or after log amplification)? Gregor Rothe > Date: Tue, 27 Jan 1998 16:16:57 -0800 (PST) > From: Joseph Trotter <trotter@scripps.edu> > To: Cytometry Mailing List <cytometry@flowcyt.cyto.purdue.edu> > Subject: Re: 7-AAD,FITC and PE > Cc: cytometry@flowcyt.cyto.purdue.edu > > Joan, > > You must compensate FL1 (FITC) signals out of FL3 (7-AAD) on most > cytometers indirectly. For example: On BDIS instruments compensation is > via dual differential amplifiers where you sample FL1 and remove a percentage > from FL2, sample FL2 and remove a percentage from FL1, and so on among > adjacent channels. If you first balance FL1, FL2, and FL3 in terms of setting a > similar sensitivity, then run compensation controls for FITC, PE and 7-AAD, the > FITC that gets into FL3 will be essentailly removed when you sample Fl2 > (PE only) and remove it from FL3 (7-AAD). If you are using *only* FITC and 7-AAD > you still need to setup FL2 in order to remove the FITC from FL3. In > this case you run FITC but use FL3 - FL2 to compensate it from FL3, even though > you will use FL1 to measure it. > > Hope this helps, > > Joe > *********************************************************** Institute for Clinical Chemistry and Laboratory Medicine University of Regensburg D-93042 Regensburg, Germany Tel. +49 (941) 944-6204 Fax +49 (941) 944-6202 E-mail: Gregor.Rothe@KLINIK.UNI-REGENSBURG.DE ***********************************************************
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