Turbo Sort Recovery

Ruud Hulspas ruud.hulspas at umassmed.edu
Thu Sep 7 14:45:18 EST 2000

I agree with Joe Trotter that the "3 puddle" method is the accurate way
to determine the drop delay. However, with the same number of outliers
in the ?1 and +1 offsets you could still have a very low recovery. It
depends on what that same number is. In Matt’s case I estimate to find
30 outliers in each offset (60 outliers total) when you use the "3
puddle" method at 500 Ev/s and sort 1500 events using a 1.0 drop
envelope. Which (I believe) is reasonable for a Vantage with TurboSort.
Ofcourse, in theory you shouldn’t find any outliers. Unfortunately,
‘fluidics’ is one of the major factors that affect a perfect drop delay.
An event of interest doesn’t always end up on the location that the
sorter predicts after it has been detected. Apparently, a particle
sometimes travels a littlebit faster or slower on its way to the ‘last
attached’ drop. The less stable the fluidics the more you expect this to
happen thus more outliers show up in the two offsets. One way to
minimize the risk of having an event end up in the wrong drop is to
increase the amplitude of the dropdrive and shorten the distance between
the detection point and the drop breakoff point. It is easy to find the
optimum distance by adjusting the position of the laser (detection point
closer to the orifice) and increasing the dropdrive to the point just
before detecting light scatter caused by vibrations in the stream from
the droplet formation.
When optimized, it should be possible to find as low as 14 outliers in
only one of the two offsets (the other offset should be empty) using the
"3 puddle" method at 500 ev/s sorting 1500 events total (> 99%


* * * * * * * * * * * * * * * * * * * * * * * * *
Life is either a daring adventure or nothing.
(Helen Keller)
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R. Hulspas, Ph.D.
Head, Cancer Center Flow Cytometry Lab
UMass Cancer Center

UMass Worcester Foundation Campus
222 Maple Ave
Rose/Reed Building, Rm 104
Shrewsbury,  MA 01545
phone: 508 856 1604
fax:    508 856 1310

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