Horseradish peroxidase modified electrode based on a film of Co-Al layered double hydroxide modified with sodium dodecylbenzenesulfonate for determination of 2-chlorophenol

Horseradish peroxidase (HRP) was immobilized on a film of Co-Al layered double hydroxide or hydrotalcite-like clay (HT) modified with sodium dodecylbenzenesulfonate, casted on a glassy carbon electrode. The sensitivity of this peroxidase-based modified electrode is limited by high current due to direct electron transfer between the enzyme and the electrode surface when hydrogen peroxide is present. However, in this case the sodium dodecylbenzenesulfonate (SDBS) surfactant blocks the direct electron transfer. Once optimized the operating conditions of the modified electrode for analyzing 2-chlorophenol, the range of linear response, at the applied potential of -150 mV vs. Ag/AgCl, was from 0.005 to 0.05 μmol L^-1 with a good correlation coefficient (0.999, n = 7). The sensitivity was 678 μA/μmol L^-1 and the detection limit was 0.002 μmol L^-1, determined using a signal-noise ratio equal to 3. The modified electrode was used to determine 2-chlorophenol in spiked tap water samples by the standard addition method. According to the measurement the new modified electrode is a good alternative as enzymatic biosensor for determination of other phenols.