Sorting problems with EPICS Altra still not solved

Matthias Heil m.heil at kerckhoff.mpg.de
Wed Mar 6 08:43:45 EST 2002


Hi Flowers,

thank you all, who replied to my last mail.

These were/are my problems setting up the hypersort modus on my Altra
sorter:
The current settings:
- 70µm flow cell tip
- 32 psi
-Frequ.: around 65.0 kHz
-Drive: ca. 18-24 %
- Delay: anything between 38 and 51 (depending on the day, the weather or
whatever)

Using the matrix mode (1 drop sort logic) I try to sort 20 beads. The beads
are SPLIT in at least three drops with a maximum of 8-10 in one drop and 3-5
in both other drops. In  addition, these drops SPRAY (spread in several
sub-drops) . This observation is very consistent and reproducable.
What we then  did according to the answers I received:
-Changing flow tips several times
-Changing flow cell body
-Cooling the sheath fluid to 16°C or 18°C
-increasing the difference between sheath and sample pressure
-sorting up to fifty beads for better statistics
-adapting the phase
-full sheath tank
-high/ low data rate

In addition, I had the Coulter service engineer here checking the system
including the fluidics pressures. He left unsuccessfully.
The Coulter people in Miami suggested that it might be an application
problem. Thank you guys!

One strange thing: Several times I was able to sort ca. 90% of the intented
bead number. This phenomenon (or should I say miracle?) occured mainly after
a manipulation (changing the flow tip or flow cell body, etc.) and lasted
only for a couple of minutes.

Are there any ideas left?

Thanks,
Matthias Heil
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