Introducing absorptive stripping voltammetry: wide concentration range voltammetric phenol detection

Carbon paste electrodes are developed for the detection of phenols via a procedure in which the phenols are allowed to accumulate in the paste via transfer from an aqueous solution prior to electro-oxidation. Importantly, the use of such paste electrodes is shown to substantially overcome the self-passivating behaviour of the phenol oxidation which usually constrains the electrode process to low concentrations and single-shot experiments. In this paper, 4-phenoxyphenol could be detected in the range from 2.5 to 40 mu M, phenol from 2.5 mu M to 60 mM and 4-methoxyphenol from 5.0 to 40 mu M. The electrodes were re-usable without surface renewal for concentrations up to 1.0 mM. The use of a bulk phenol solution for pre-concentration via absorptive uptake into a bulk phase followed by electrochemical quantification represents a new form of electroanalysis, namely absorptive stripping voltammetry complementary to adsorptive stripping voltammetry where accumulation occurs via adsorption on an electrode surface.