2-chamber, 3-electrode set-up procedure
by HMJensen with help from Ben Gross in the El-Naggar Lab, significant revisions by MA TerAvest
Please refer to pdf Electrochememical system setup 20160129.
Before getting into it, check the following:
- Reference electrodes: Does the Ag wire appear white? Or black? If white, see the video protocol “refreshing reference electrode”
- Graphite electrodes: cut to desired size, saturate with milli-Q water, store in Milli-Q
- Pt wire electrodes: Are the electrode wires shiny? Dull? If dull, then use fine sand paper to remove any corrosion.
- Cation exchange membrane: cut to size and store in 4% NaCl
- Glass chamber set-up: Check that all of the components and tubing are clean.
- Media: Check that all of the media solutions are available.
- Prepare your solutions for working and counter chamber (typically M9 medium base).
- Assemble the 2-chamber system: (see video procedure reactor_assembly)
- Insert the Pt cathode electrode on the left-hand chamber through the top septum.
- Insert the graphite anode into the right-hand chamber through the top septum.
- On the side ports of each half, screw down caps with septa.
- Place a stir bar in the working chamber.
- Very lightly grease the glass edges of the reactor halves. Over-greasing leads to grease on electrodes and is hard to clean.
- Place the membrane in the center of the o-ring gasket.
- Use the circle clamp to secure the two sides to one another. DO NOT OVER TIGHTEN.
- Fill the counter chamber with 140 mL of your solution (usually M9 base).
- Fill the working chamber with 135 mL of your solution (usually M9 base)
- Place the septa screw caps on the tops of each the anode and cathode side and leave a quarter to a half turn unscrewed for autoclaving.
- Autoclave the assembled cells. Let the media cool after autoclaving.
- Add supplements to the working chamber as needed (sterile technique!) Usually:
- 1.4 mL Mineral supplement
- 1.35 mL Vitamin supplement
- 1.35 mL Amino Acid supplement
- Insert reference electrode into side port of working chamber (clean with ethanol first)
- Set up cells in their positions and start gas flow and potentiostat (see video protocol start_N2&potentiostat)
- Sparge and take background measurements for >5 hours.
- Inject bacteria