Amperometric flow injection analysis of hydroquinone in dermatological creams using a porous diamond-like carbon electrode.

A porous diamond-like carbon film deposited on vertically aligned multi-walled carbon nanotubes (DLC:VAMWCNT) was evaluated as an electrode material in flow injection analysis (FIA) with amperometric detection. The redox behavior of hydroquinone (H 2 Q) was carried out as proof of concept. From cyclic voltammetry tests, H 2 Q gave a heterogeneous electron transfer rate constant (k 0) of 4.9 × 10−3 cm s−1, which is comparable or better than those obtained with conventional electrodes. For the H 2 Q determination with the FIA-amperometry system, optimizations were performed regarding the supporting electrolyte, applied potential and FIA parameters (flow rate and sample injection volume). Under optimal conditions, the amperometric response of the DLC:VAMWCNT electrode was linear in the H 2 Q concentration range from 1.0 × 10−6 to 1.0 × 10−4 mol L−1, with a limit of detection (LOD) of 7.7 × 10−7 mol L−1. Interestingly, the DLC:VAMWCNT electrode displayed a very stable response under hydrodynamic conditions, with no memory effect while retaining accuracy towards the analysis of commercial H 2 Q-based dermatological creams. From these findings, DLC:VAMWCNT appears to be an outstanding candidate for flow injection analysis systems coupled to electrochemical detection. [Display omitted] • Porous diamond-like carbon prepared on vertically aligned carbon nanotubes • Amperometric flow injection analysis with porous diamond-like carbon electrode • Porous-diamond like carbon electrodes display stable response under flow conditions. • Hydroquinone amperometric determination in cosmetic samples [ABSTRACT FROM AUTHOR]