Have you tried to use disposable (modified) electrodes...? I mean... each electrode, you can do one measurement.

Please see these articles:

J. Braz. Chem. Soc., Vol. 23, No. 10, 1834-1838, 2012.

Electroanalysis 2011, 23, No. 11, 2521 – 2525

Electrochemistry Communications 12 (2010) 216–218

You`re using platinum or Gold electodes? Than may glassy carbon as working electode may help, Do you polish your electrodes bevor use? Or flaming bevor use??

Do you need a particular pH, or can you change? Solvent mixtures? SPEIS or SGEIS techniques?...........nothing help?

than may help dipping the Pt-electrode for some minutes in a solution of trifluoracid with small amounts ot ethylengylcol/ terephtalat polymer (0.05%), shake and dry at 120°C 20 minutes......may also a Glycin/ananin/leucin bath could work.......

If nothing helps....polishing after every cycle!

good luck

Dear Anna,

the situation may be very different depending on the electrode material you use. Sometimes biological molecules adsorb on electrodes via electrostatic forces. Should this be your case, I suggest to use a high concentration of KCl (> 0.6 M) to avoid electrostatic binding. Alternatively, one may chemically modify the surface of a metal electrode with a self-assembled monolayer such that (i) it prevents direct binding of the amino acid to the metal and (ii) it promotes the electron transfer. Also in this case a high salt concentration may avoid electrostatic binding of the amino acid to the monolayer.

I hope it helps,

Diego

Thanks to all, I use screen printed carbon. In principle method could be single use, but I would like to reuse them few times, at least get a calibration curve on a single electrode. I could try high salt concentration.

If it's the electrode reaction that leads to the fouling (like e.g. serotonin oxidation does) there's not a whole lot you can do about it. Amine oxidation is usually electrocatalytic and needs adsorption at energetic metal atoms for electron transfer to occur. Electron transfer only takes place over distances similar to a bond length so you can't stop adsorption without stopping the electrode reaction. that said, some materials are less vulnerable than others. Boron-doped diamond is better than glassy carbon or carbon fibre since the oligomers produced by the reaction are only weakly attached. In any case, you can burn them off with a large positive excursion in the potential. This latter approach typically does not work with other less resistant material.

The reaction is likely a ec reaction mechanism: oxidation followed by deprotonation then radical addition to either reactant or reaction product to form a poorly-soluble film. Using lower concentrations and larger electrodes (or slower flow rates/ rotation speeds for hydrodynamic measurements) will reduce the product flux and buy you a little longer before the electrode is fouled.

You can use an electrode Luggin, placing a platinum filament. thus prevent pollution of your electrode. Greetings from mexico

Catechol type amino compounds form a polymer like product on carbon electrodes. Refer. J. Electrochem. Soc., 127(1980) 1489, J. Electroanal. Chem. 46 (173) 313.

Hi

I had read that some surface modifier materials like gelatin or triton X-100 adding in supporting electrolyte prevents adsroption onto the electrode surface.

Try pulse amperometric detection

How to reuse a screen printed carbon electrode few times in the detection of biomolecules that adsorb on the electrode?

See in the article below a specific answer to this question:

http://www.sciencedirect.com/science/article/pii/S0925400514005073