Remotely Diagnosable: YES

Remotely fixable: YES*


Ideally "good" water or buffer for suspending particles for measurement should have fewer than 20 particles visible per frame when using scatter mode and 85-90% sensitivity.


If users see higher particle counts than this then there are several potential causes


Incorrect camera settings  

  • Diagnosis: Are they using the correct SOP for the type of measurement the want to make? Each measurement type (beads, EV's, fluorescence, etc.) has an SOP set up for it. It is possible for a user to adjust settings from the defaults for a given SOP and in this case the SOP selected on the measurement tab will say "no SOP". 
  • Solution: Have them select a reasonable SOP from their list and see if the problem persists.

Soiling

  • Particles adhered to the walls of the cell cause issues with static "particles" detected at certain positions across the cell and focusing issues creating measurement artifacts.
  • Diagnosis: Perform an auto-alignment and observe the parabola. a "good" result should make a symmetrical U-shape on the graph and have a curvature value equal to or more negative than -700mv.
  • Solution: Have the users clean the cell with 2 drops of green solution in distilled water, rinse with distilled water and see if the problem persists. 


Old buffer 

  • PBS solutions can crystalise and form particles as they get older, this is particularly common if large volumes of PBS are left in the buffer reservoir
  • PBS deposits will also precipitate in the reservoir and can be released back into solution if old buffer is replaced with fresh buffer
  • Diagnosis: Injecting fresh buffer in though the injection port to see if the fresh buffer is in better condition
  • Solution: Reservoir should be emptied, cleaned of all precipitate and then filled (max 50ml) with fresh buffer


Water is not particle-free/buffer not made with particle-free water

  • Sometimes a filter can break down or site staff can make their buffers with unfiltered mains water by mistake.
  • Diagnosis: If injecting fresh buffer still shows excessive particles, try injecting particle-free water and/or buffer and particle-free water from another batch or source., If some liquids injected have fewer than 20 particles visible per frame at 90 sensitivity, then there is something wrong with the buffer or water they were using
  • Solution: Customer should make fresh solutions with particle-free water