Cesium Gluconate internal solution kit

To make your internal solution:

1. Dissolve the 1g of CsOH in 6.67ml dH₂O to make a 1M CsOH solution
2. Dissolve the Cesium gluconate internal solution kit base in 80ml dH₂O for the 100ml kit and 160ml dH₂O for the 200ml kit. Ensure that it is thoroughly mixed and do not allow to excessively stand around as the solution degrades at room temperature.
3. Use the 1M CsOH solution to adjust the pH of the internal solution to pH 7.2, do this extremely carefully in a dropwise manner as to not overshoot the desired pH.
4. Measure the current solution osmolarity (it will be currently too high) then add dH₂O slowly to adjust the osmolarity down to the desired osmolarity for your experiments (290-295 mOsm is a good place to aim and it should be around 10mOsm less than the external solution)
5. Aliquot into the amount of internal solution needed for a days' experiments, snap freeze and store at -20°C.

To use your internal solution:

1. Remove the aliquot from the freezer and warm to room temperature before using to load your patch pipette.
2. Make sure to only use a fresh aliquot each day and do not reuse for multiple days due to the degradation of the solution at room temperature.

-20°C

Only remove from the freezer when ready to make up the internal solution as components of this kit degrade at room temperature.

This kit contains:

• Cesium gluconate internal solution kit base as a ready to dissolve powder
• Cesium hydroxide (CsOH, 1g) for adjusting pH of the final internal solution. This will need dissolving in 6.67ml dH₂O to make a 1M solution for pH adjustment.