Sack: Agar Bridge Formation: Difference between revisions
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A procedure for the formation of agar salt bridges.<br> | A procedure for the formation of agar salt bridges.<br> | ||
The purpose of an agar salt bridge is to provide an electrical connection to the bath solution while minimizing the transfer of ions or solute from the electrical environment.<br> | The purpose of an agar salt bridge is to provide an electrical connection to the bath solution while minimizing the transfer of ions or solute from the electrical environment.<br> | ||
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When cool, remove any excess agar from the outside of the bridges and examine for bubbles. Usable bridges should be placed in fresh KCl solution for long-term storage. Bridges may be covered and safely stored in the refrigerator for up to 90 days.<br> | When cool, remove any excess agar from the outside of the bridges and examine for bubbles. Usable bridges should be placed in fresh KCl solution for long-term storage. Bridges may be covered and safely stored in the refrigerator for up to 90 days.<br> | ||
Salt bridges can be discarded after each use or reused several times. | Salt bridges can be discarded after each use or reused several times. | ||
Latest revision as of 16:13, 15 January 2013
A procedure for the formation of agar salt bridges.
Formation of bridgesBridge structures can be formed from any tubular material which is both chemically and electrically inert. Many researchers use either polyethylene or glass tubing. Due to its structural rigidity we recommend glass capillary tubing with an inside diameter of 0.86 mm. Use of larger diameter tubing can increase the transfer of material across the bridge while smaller diameter tubing can increase the series resistance of the conducting pathway. The proper choice of tube diameter will depend on your application and electronics. We suggest that you start with our recommendation and make changes as necessary. Preparing agarAn agar solution is formed by heating a mixture of 2-5% agar in 1M KCl (w/v). A final volume of 3 ml is sufficient to fill 50 bridges. This mixture should be covered and gently heated, with stirring, on a hotplate until the agar is completely dissolved (solution becomes clear) and bubbles are just beginning to form.
Loading bridges StorageWhen cool, remove any excess agar from the outside of the bridges and examine for bubbles. Usable bridges should be placed in fresh KCl solution for long-term storage. Bridges may be covered and safely stored in the refrigerator for up to 90 days. |