Geoff, you say: > ... From my own experience a three drop > envelope gives better purity over a wider range of Dop Delays than a > 2 or 1 drop delay.With a one drop envelope drop delay must be spot on, > any drift and purity is lost.I'm sure lots of people reading this with > ageing Vantages get some varation in drop delay it seems to me this > is being compensated for by a three drop envlope.What do other people > use? A friend of mine with a new Vantage SE uses a 1.5 drop envelope I > dont see the logic in this as half the time it sorts 2 drops and half > the time it sorts 1!Which is best? I share your concern about sorting single drops. Sorting 1.5 or 2 drops per event gives an added safety net in case of drift or inaccurate drop delay setting. The way I understand it (and someone from B_D *should* correct me if I'm wrong) with 1.5 droplet sorts, if the cell is detected to be in the first quarter of the drop, the previous drop is also sorted. If the cell is in the last quarter, the following drop is also sorted. Otherwise, only the drop with the cell is sorted. It takes only a little thought to realize that, if your breakoff setting is in error by less than one quarter droplet, you will not lose *any* cells in 1.5 drop sorting. Similarly, with 2-droplet sorting, where the choice of additionally sorting the preceding or following droplet depends on whether the cell is in the first or last *half* of its droplet, your breakoff setting is allowed to be up to 0.5 drops in error before you start losing cells. Which one is best depends on your own experience of how accurately you can set your breakoff and how much your sorter drifts. We use 2 drop sorting on both our FACS II and FACStar+ for the reason of the 0.5 droplet safety net. Frank. Frank Battye, \ / < The Cytometry Laboratory Dora Kaminaris, \__/ <<<<< The Walter & Eliza Hall Institute Viki Lapatis, ---------!!<<<<<<<< Victoria 3050, AUSTRALIA Jennie Parker and /!!\ <<<<< ph: 61_3_9345 2540 fax: 61_3_9347 0852 Catherine Tarlinton o !! \ < in:: "facs_copy@wehi.edu.au"
This archive was generated by hypermail 2b29 : Sat Mar 10 2001 - 19:31:07 EST