Table 4 |.

Troubleshooting suggestions for possible problems at each of the indicated steps of the nPOP protocol.

Step	Problem	Cause	Solution
nPOP Procedure
9, 33	DMSO conditioning droplet tests show residual DMSO on nozzle affecting droplet performance	Residue on the surface of the nozzle is causing DMSO to persist.	Dab the droplet of residual DMSO with a lint free wipe to dry the nozzle surface
10,34	DMSO droplet images reveal dispensing inconsistency.	Aberrant DMSO dispensing issue, occurs rarely.	Adjust field files correspondingly, removing those with successful dispensing, and redispense reagent to relevant slide positions.
17	Nozzle clogged during cell dispensing	Large cell debris blocked the nozzle outlet and reduced droplet stability.	Pause run, flush sample, run AirEx task, and aspirate new cell suspension to continue.
25	Trypsin QC spot presence decreases in later Fields	Undissolved protein or debris from Trypsin solution occluded the orifice during aspiration reducing the total volume aspirated	Clear dispense fields with recognizable QC spot, restart run to dispense Trypsin to all arrays with poor trypsin QC spot
26	Droplets may dry or swell overnight	Improper setting for dew point correction factor	The suggested setting is +2 C but this value may need to be slightly increased or decreased depending on lab.
33	Label dispense failure	Improper label pickup or occasional error.	Load the field file for the label that failed and initiate redispense. Repeat for each failed label.
39	TEAB dispense failure	Aberrant TEAB dispensing issue, occurs rarely.	Adjust field files correspondingly, removing those with successful dispensing, and redispense reagent to relevant slide positions.
52	Residual reaction volumes after pickup are not negligible.	Target teach height is too high from the slide surface to collect pooling volume completely	Decrease the target teach height to ~1100 um from slide surface and restart the same pickup run to the same plate