Figure 1.
A. Chemical structures for biphenyl-4-thiol (Biphenyl), 4-(phenylethynyl)benzenethiol (OPE) and undecane-1-thiol (C11) used to from SAMs on gold electrodes. B. The electrochemical setup.
Table 1.
Characteristics of SAMs on golda.
Figure 2.
Square wave voltammetry of several TNT concentrations in air-saturated 100 mM potassium phosphate, buffed at pH 8.
A. The response of TNT at a C11 modified gold electrode measured at 15 Hz. B. The response of TNT at a C11 modified gold electrode measured at 60 Hz including a comparison to a bare gold electrode. C & D. The response of TNT at a OPE modified gold electrode measured at 15 Hz and at 60 Hz, respectively. E & F. The response of TNT at a Biphenyl modified gold electrode measured at 15 Hz and at 60 Hz, respectively.
Table 2.
Electrochemical experimental data for the reduction of TNTa.
Figure 3.
Characteristics of electrochemical detection of TNT.
A. Background subtracted peak current vs. [TNT] measured at the first reduction of TNT from the corresponding square wave voltammograms (average of two electrodes). B Slope (µA/ppm) of the calibration curves vs. SAM type and Hz. Black = 15 Hz, Red = 60 Hz.
Figure 4.
Background subtracted square wave voltammograms of TNT at modified gold electrodes with experimental data (blue trace) compared to simulations (red trace).
Fig. 4A and 4B show the response at a C11 SAM at 15 Hz (A) and 60 Hz (B). For 4B the simulation at 60 Hz could not fit the experimental data, and the parameters for the 15 Hz simulation are repeated for comparison. Figs. 4C and 4D shows the response at the OPE SAM at 15 Hz (A) and 60 Hz (B), Figs. 4E and F shows the response at the biphenyl SAM at 15 Hz (A) and 60 Hz (B). Experimental conditions are listed in Fig. 2. Area of the electrode = 0.50 cm2, [TNT] = 10 ppm (44 µM). Fitted parameters are listed in Table 2 and simulation settings are listed in the text.
Table 3.
Electrochemical simulation outputa.