PEDOT-RGO Case Study

Cyclic voltammograms for 50 moldm-3 catechol were recorded with plain GCE, PEDOT-GO, PEDOT-rGO and PEDOT-rGO incorporated with LAC at pH 7.0 and scan rate 50 mVs-1 Fig. 4.3.4. Fig 4.3.4A present CVs and the anodic peak current observes for dopamine are bare small redox peak was observed. The modification of PEDOT-GO and PEDOT-rGO were increase in increase in the redox reak compared with bare electrode. The incorporation of LAC on the PEDOT-rGO gives decrease in the oxidation and increase in the reduction because of o-dopaquinone is changed as dopamine enzymatic oxidation. The increase in the reduction peak current of enzyme electrode is due to reduction of more o-dopaquinone convert to dopamine by 2e- transfer process. Thus the modification
The result shows between the oxidation and reduction peak with the scan rate in the range of 10-250 mVs-1 (Fig. 4.3.4.1a). The linearity between the square root of the scan rate and the anodic and cathodic peak current reveals diffusion controlled reduction. Moreover, the electroactive area can be estimated by Randles- Sevcik equation [2] for the modified electrode. The diffusion coefficient of enzymatically oxidized dopamine was obtained from slope of the straight line obtained in the plot Ipc versus υ1/2 (Fig. 4.3.4.1b). The electroactive area of the prepared electrode is calculated by equation [2] and it is 0.0396
HPLC
The performance of the fabricated electrochemical biosensor using PEDOT-rGO-LAC was compared with that of HPLC. Quantification of dopamine present in human urine extract was done by addition of three different concentrations of dopamine using the developed biosensor. The quantification and percentage of recovery were determined and the results are presented in table 4.3.2.
HPLC was performed for the determination of dopamine in the same human urine extract sample by external standard method. Different concentrations of dopamine present in the human urine were determined by addition method. The recovery was determined by spiking a human urine extract sample with three different additions of dopamine (6). Fig. 4.3.7 illustrates the chromatogram of the standard of dopamine and one human urine small extract sample. Quantification of dopamine and recovery percentages was found out from the obtained results. The results obtained from the present method and HPLC are comparable and hence the developed biosensor can extremely good be used for the determination of dopamine in human urine