
19
Collect generated droplets
24.
After finalized droplet production, confirm that dPCR droplets have been produced. dPCR droplets will sink to
the bottom of the collection well and form a white layer with a clear buffer phase on top.
25.
If droplets are visible, collect droplets from the Exit-well (#D).
26.
Optional: 200 μl dPCR-buffer (surplus in the dPCR-buffer well #A) can be used to “wash” residual droplets from
the shelf inside the exit well - where droplets are entering the well #D.
27.
Remove excess liquid in wells #A and #B before storage of the cartridge.
28.
Store the cartridge at room temperature in the provided bag with the gasket placed on top of the cartridge.
A total volume of droplets and buffer around 300-400 μl is expected to be collected after droplet production.
29.
Dispense the droplets into four PCR-tube aliquots (of approximately 80-90 μl). NB: Please note that dPCR
droplets sediment rapidly during handling. To ensure equal distribution into the aliquots, be sure to mix gently
by pipetting up and down between each pipetting step.
30.
Place the PCR-tubes in a thermocycler and run the following program. A temperature ramp rate of 1,5°C/sec
or less is suggested.
Temperature
Duration
Cycles
30°C
5 sec
1x
94°C
2 min
Slow ramp
1,5°C/sec
94°C
3 sec
Slow ramp
1,5°C/sec
40x
Annealing temp.
30 sec
24°C
30 sec
1x
Store the droplets at 4°C after PCR.
31.
Continue with dPCR droplet sorting (see Chapter 4) within 24 hours to maintain the integrity of the DNA
fragments. dPCR droplets can be stored after PCR at 4°C for up to 24 h if proceeding with DNA enrichment.
dPCR droplets are stable at 4°C up to 2 months, however, storage longer than 24h will compromise DNA
quality and enrichment and should be avoided.
Good pause point: Store dPCR droplets after PCR at 4°C for up to 24 hours.