Cost Effective Graphite Based Sensor for Simultaneous Detection of Phenolic Isomers

Abstract

A facile and low-cost electrochemical technique for the detection of phenolic isomers (PIs), hydroquinone (HQ), catechol (CC), and resorcinol (RS), in aqueous system was developed. In this research, graphite based electrode (GBE) fabricated from a regular HB pencil (Brand: Faber Castell). HB pencil collected from the local stationary shop was used for fabricating working electrode termed as HB pencil electrode (HBPE) in the experiment. Then HBPE was also modified electrochemically by amino acid (AA), namely Glycine (GLY) and Aspartic Acid (ASA). Modified electrodes were termed as GLY-HB and ASA-HB in total working process. HBPE, GLY-HB and ASA-HB electrodes were used in detection of PIs by CV and DPV. The bare HBPE showed good electroanalytical activity effect on the redox reaction towards PIs. Both GLY-HB and ASA-HB electrodes showed catalytic activity on the redox reaction to PIs over HBPE. A series of pH dependent reactions were performed in phosphate buffer solution (PBS) and total analyses and detection processes were continued at pH 6.8 which was used as the supporting electrolyte. The influences of scan rate and concentration on the redox behavior of HQ, CC and RS in both GLY-HB and ASA-HB were discussed. The anodic peak current versus the concentration of HQ, CC and RS showed a linear relationship. The variation of peak current was also plotted with Square root of scan rate. The electrochemical processes were diffusion controlled in all cases. The constructed electrodes produced reproducible and stable results in all cases. The limit of detection (LOD) was calculated by signal-to-noise ratio (S/N) = 3. In simultaneous detection, the LOD for HQ, CC and RS at bare HBPE were 12.473 μML-1, 16.132 μML-1 and 25.25 μML-1, respectively. The sensitivity for HQ, CC and RS is 470.481 μA/mM/cm2, 363.781 μA/mM/cm2 and 232.416 μA/mM/cm2, respectively at bare HBPE. LOD for HQ, CC and RS at GLY-HB were 5.498 μML-1, 7.119 μML-1 and 14.794 μML-1, respectively and those were 22.459 μML-1, 25.478 μML-1 and 38.303 μML-1, respectively at ASA-HB in simultaneous detection. The sensitivity for HQ, CC and RS is 364.785 μA/mM/cm2, 282.712 μA/mM/cm2 and 135.560 μA/mM/cm2, respectively at GLY-HB and 374.483 μA/mM/cm2, 330.108 μA/mM/cm2 and 219.574 μA/mM/cm2, respectively at ASA-HB in simultaneous detection. Cost of one HBPE is about 5.00 BDT, one GLY-HB or ASA-HB electrode is about 7.00 BDT while one glassy carbon (GC) electrode is 14,000.00 BDT. So HBPE is at least 2800 times and that for GLY-HB or ASA-HB electrode is 2000 times cheaper than conventional commercial GC electrodes.