Electrochemical determination of electroinactive guests of β-cyclodextrin at a self-assembled monolayer interface
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A novel determination method of electroinactive molecules by means of electrochemical technique is presented. A new self-assembled monolayer containing cyclodextrin (CD) is prepared with mono(6-o-p-tolylsulfonyl)-β-cyclodextrin. Although this derivatization process leads to a β-CD coverage of 10% of a full monolayer, this layer shows an effective host-guest response to ferrocene. The interfacial ferrocene complexation gives a response similar to that expected for a Langmuir adsorption isotherm yielding a stability constant of 4.2×104 mol-1.L and a maximum ferrocene coverage of 8.6×10-12 mol/cm2. The redox peak currents of the surfaceconfined ferrocene decrease upon addition of competing β-CD guest species to the solution, such as m-toluic acid (mTA) and sodium dodecyl sulfonate (SDS). This principle has been used for the determination of the electroinactive molecules, mTA and SDS in the concentration ranges of 0.8-2.7 μmol/L and 5–100 nmol/L, respectively.
KeywordsVoltammetry self-assembled monolayer host-guest inclusional complexation β-cyclodextrin m-toluic acid sodium dodecyl sulfonate
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