Resolving Common Qnano Issues In Different Situations - Izon qNano User Manual

2 / RESOLVING COMMON QNANO ISSUES IN DIFFERENT
SITUATIONS
Only electrolyte in the pore
ISSUE
Cannot establish
baseline current
Unstable baseline current
Running synthetic or inorganic particles
ISSUE
Stable baseline current, but
very few particles
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ACTIONS THAT MAY BE NEEDED
— Unplug and replace USB cable to restore the
connection between the qNano and the PC. Ensure
voltage is switched on and non-zero.
— Use reverse pipetting (as described in the instrument
operation section) to prevent bubbles forming on top
of the pore and blocking the fluid flow.
— Gently mix the fluid in the upper fluid cell without
introducing any bubbles.
— If consistently destabilising, wash and dry the upper
fluid cell, and gently replace the fluid in the lower fluid
cell to remove any bubbles.
ACTIONS THAT MAY BE NEEDED
— Increase the sample concentration. Use low pressures
until you have a stable system, otherwise you risk
blocking the pore.
— Consult the sample preparation guide and enhance
suspension stability.
— If your sample particles have positively charged
surface/terminal groups, they are likely to stick to
and block the pore instead of going through. For
concentration and size analysis only, you can suspend
particles in Tris buffer, adjusted to pH 10, with 0.03%
Triton-X, to mask the charge on the particles to allow
them to pass through the pore. Charge analysis will
not be possible for particles with a positive surface
charge, as zeta potential will be altered with pH.
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