The use of a graphite-castor oil polyurethane composite electrode for the determination of hydroquinone in photographic developers

The performance of a new graphite-castor oil polyurethane composite electrode in the determination of hydroquinone in photographic developers in a differential pulse voltammetric (DPV) procedure is described. The 60% (graphite, w/w) composite electrode presented good stability, repeatability and accurate response. Limit of detection of 934 nmol L-1 was observed for hydroquinone within a linear dynamic range from 66 to 530 nmol L-1. The determination of hydroquinone in a photographic developer sample showed agreement with the label values in a 95% confidence level with maximum 2% relative error and recoveries between 100.1 and 100.4%. No need of sample preparation was required since the p-methylaminophenol sulfate (metol) present in the developer formulation did not interfered in the measurements. (c) 2005 Elsevier B.V. All rights reserved.