Hello all, 1) I was on a visit to another department the other day where a FACScan was being used to diagnose MRD using a multi-colour protocol at flow rates around 2000/sec. On my machines (Beckman-Coulter Elites) I would expect to see a considerable amount of coincidence at these rates. My question is, are FACScans less susceptible to this effect than elites at these rates and if not, what data rate would be best to minimize this effect. 2) I have been assaying the level of expression of a cell surface marker by comparing the fluorescence obtained against 'Spherobead' calibration beads, the fluorescence obtained are then expressed as MESF levels -so far, so good. I have upgraded the laser on the machine (an epics elite) from the old Cyonics 15mW unit to an Innova 90 -I now use 100mW excitation. My concern is that the fluorescein on the cells may have reached saturation whilst the proprietary fluorescent compound on the calibration beads has not -thus giving a low reading for the cells. I intend to try different levels of excitation when I get a minute, in the mean time, I would appreciate any thoughts Best regards, Arnold _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Arnold Richard Pizzey Department of Haematology Royal Free and University College London Medical School 98 Chenies Mews London WC1E 6HX U.K voice: +44 020-7679-6234 Fax: +44 020-7679-6222 email: a.pizzey@ucl.ac.uk _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
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