Table 2.

Troubleshooting for the pipette tip assay (s-ARU method)

Problems	Solutions
Growth in the cell-free gap	- The pipette tip is not properly fixed in the center of the well or
	- Pipette tip is tilted or
	- Pipette tip is short
The cell-free area is not spherical/circular	- The cover plate is not fixed properly with paper tape or
	- The plate was tempered or
	- The medium and cells have entered under the pipette tip
Contamination	- The pipette tips are not sterile/non-autoclaved or
	- The pipette tips were not processed within the hood or
	- The glue/fixative/adhesive used might have contaminated the medium due to over spilling or shaking
The cover plate does not fix the plate properly	- The pipette tips are not homogeneously shortened or
	- The pipette tip is not properly fixed in the center of the well
Results variation	- The variation in results in mostly due to the density of the cells or
	- Floating cells occupying the NO growth zone