Electrochemical Behaviors And Determinations Of Several Food Antioxidants On Carbon Electrodes

With rapid development of the food industry, food quality and food safety draw more and more attentions. Antioxidants, as one kind of food additives, play important roles in food. Thus analysis and detection for food antioxidants is becoming increasingly important.At present, chromatography, capillary electrophoresis and electrochemical methods are powerful for the analysis and detection for food antioxidants. In this work, electrochemical methods such as cyclic voltammetry(CV) and i?t technique are utilized to investigate electrochemical behaviors of commonly used food antioxidants including tertiary butyl hydroquinone(TBHQ), propyl gallate(PG) and ascorbic acid(AA). Based on this, analysis and detection for above three food antioxidants is achieve on carbon electrodes including glassy carbon electrode(GCE), carbon paste electrode(CPE) and grapheme modified carbon paste electrode(RGO/CPE). Details are listed below.(1) On GCE as working electrode, TBHQ creates a pair of CV peaks in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.033 V and Epc=-0.028 V. Peak current ipa?ipc indicates a quasi-reversible redox process. Oxidation peak current and reduction peak current are proportional to square root of scan rate in the range of 0.02 ~ 0.30 V/s, which indicates the electrode process is controlled by diffusion. Steady state current is linear with TBHQ concentration from 1.0×10-5 to 1.9×10-4 mol/L(R2=0.9996)with a detection limit of 2.8×10-6 mol/L. Detection for artificial TBHQ sample gains relative standard deviation of 5.38% and a recovery ratio of 74.0% ~ 137.5%.On CPE as working electrode, TBHQ creates a pair of CV peaks in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.312 V and Epc=-0. 208 V. Peak current ipa?ipc indicates a quasi-reversible redox process. Oxidation peak current and reduction peak current are proportional to square root of scan rate in the range of 0.02 ~ 0.25 V/s, which indicates the electrode process is controlled by diffusion. Steady state current is linear with TBHQ concentration from 1.0×10-5 to 1.9×10-4 mol/L(R2=0.9945)with a detection limit of 7.1×10-6 mol/L. Detection for artificial TBHQ sample gains relative standard deviation of 8.86% and a recovery ratio of 39.5% ~ 88.8%.On RGO/CPE as working electrode, with RGO carbon ratio is 0.5 μL/mg, TBHQ creates a pair of CV peaks in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.306 V and Epc=-0. 205 V. Peak current ipa?ipc indicates a quasi-reversible redox process. Oxidation peak current and reduction peak current are proportional to square root of scan rate in the range of 0.02 ~ 0.30 V/s, which indicates the electrode process is controlled by diffusion. Steady state current is linear with TBHQ concentration from 4.0×10-5 to 1.1×10-4 mol/L(R2=0.9987)with a detection limit of 2.1×10-6 mol/L. Detection for artificial TBHQ sample gains relative standard deviation of 5.24% and a recovery ratio of 90.2% ~ 108.8%.(2) On GCE as working electrode, PG creates a CV oxidation peak in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.149 V. Oxidation peak current is proportional to scan rate in the range of 0.02 ~ 0.30 V/s, which indicates the electrode process is controlled by surface. Steady state current is linear with PG concentration from 1.0×10-5 to 1.1×10-4 mol/L(R2=0.9963)with a detection limit of 3.8×10-7 mol/L. Detection for artificial PG sample gains relative standard deviation of 5.61% and a recovery ratio of 68.0% ~ 108.0%.On CPE as working electrode, PG creates a CV oxidation peak in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.268 V. Oxidation peak current is proportional to scan rate in the range of 0.02 ~ 0.10 V/s, which indicates the electrode process is controlled by surface. Steady state current is linear with PG concentration from 4.0×10-5 to 1.1×10-4 mol/L(R2=0.9980)with a detection limit of 3.3×10-6 mol/L. Detection for artificial PG sample gains relative standard deviation of 7.82% and a recovery ratio of 68.3% ~ 86.0%.On RGO/CPE as working electrode, with RGO carbon ratio is 0.25 μL/mg, PG creates a CV oxidation peak in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.260 V. Oxidation peak current is proportional to scan rate in the range of 0.06 ~ 0.30 V/s, which indicates the electrode process is controlled by surface. Steady state current is linear with PG concentration from 3.0×10-5 to 9.0×10-5 mol/L(R2=0.9975)with a detection limit of 7.4×10-6 mol/L. Detection for artificial PG sample gains relative standard deviation of 2.81% and a recovery ratio of 73.2% ~ 78.6%.(3) On GCE as working electrode, AA creates a CV oxidation peak in 0.2 mol/L p H 6.0 PBS with peak potential of Epa=0.335 V. Oxidation peak current is proportional to square root of scan rate in the range of 0.02 ~ 0.30 V/s, which indicates the electrode process is controlled by diffusion. Steady state current is linear with AA concentration from 1.0×10-5 to 1.9×10-4 mol/L(R2=0.9980)with a detection limit of 4.6×10-6 mol/L. Detection for artificial TBHQ sample gains relative standard deviation of 4.52% and a recovery ratio of 88.0% ~ 1118.8%.On CPE as working electrode, AA creates a CV oxidation peak in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.454 V. Oxidation peak current proportional to square root of scan rate in the range of 0.02 ~ 0.10 V/s, which indicates the electrode process is controlled by diffusion. Steady state current is linear with AA concentration from 5.0×10-5 to 4.0×10-4 mol/L(R2=0.9906)with a detection limit of 5.3×10-6 mol/L. Detection for artificial AA sample gains relative standard deviation of 11.75% and a recovery ratio of 42.0% ~ 43.1%.On RGO/CPE as working electrode, with RGO carbon ratio is 0.5 μL/mg, AA creates a CV oxidation peak in 0.2 mol/L p H 7.0 PBS with peak potential of Epa=0.345 V. Oxidation peak current is proportional to square root of scan rate in the range of 0.02 ~ 0.10 V/s, which indicates the electrode process is controlled by diffusion. Steady state current is linear with AA concentration from 5.0×10-5 to 4.0×10-4 mol/L(R2=0.9969)with a detection limit of 2.2×10-6 mol/L. Detection for artificial AA sample gains relative standard deviation of 3.69% and a recovery ratio of 61.0% ~ 66.6%.Experiments show that, RGO / CPE has making reproducibility and good stability for detection TBHQ、PG and AA.