Table 3 |.

Troubleshooting table

Step	Problem	Possible reason	Solution
1,4,8	The size and shape of the pulled tip are not reproducible	The puller has not warmed up	Turn the puller on and let it warm up for at least 15 min before pulling the tips
		Dirty retro mirror	Clean the mirror with Kimwipes and ethanol
		The capillary is not correctly positioned	Carefully position the capillary in the puller to ensure it is correctly placed in the V-groove of the puller bar
3	The solvent is not flowing through the capillary when pushed with a syringe	One of the connections is leaking The pulled tip is closed	Check the connections Disconnect the tip from the syringe, and examine it under microscope. If the tip is closed, repeat Steps 1–3
12,13	MS signals are unstable	Unstable flow of the solvent through the nanospray capillary The solvent flow delivered by the primary capillary is too low	Balance the solvent flow between the primary and nanospray capillary by adjusting the position of the nanospray capillary relative to the mass spectrometer inlet. If air bubbles are observed inside the nanospray capillary, move the capillary further away from the mass spectrometer inlet
			Examine the primary capillary tip under a microscope. If the tip is clogged, pull the capillary to make a new tip. If the new tip becomes clogged again quickly, most likely the other side of the capillary is broken. Repeat Steps 1–4 to make a new primary capillary
16,17	A sudden and marked change occurs in the amplitude of the shear force probe vibration at a selected frequency	The shear force capillary may be broken One of the wire connections may be broken	Examine the shear force capillary under a microscope. If the tip is broken, replace it with a new probe Check the connections using a multimeter, and reconnect the broken wire
23	The nano-DESI probe crashes into the sample or loses contact with the sample during data acquisition	The vertical position of the nano-DESI probe relative to the shear force probe needs to be readjusted	If the nano-DESI probe crashes into the sample, which means the nano-DESI probe is positioned too close to the sample, move the shear force probe down closer to the sample using a stepping controller. This will increase the distance between the sample and the nano-DESI probe
			If the nano-DESI probe loses contact with the sample, move the shear force probe up further away from the sample, using a stepping controller, until the liquid bridge is formed between the nano-DESI probe and the sample