| The design, characterization and application of two complimentary analytical tools useful in the analysis of electroactive substances of pharmaceutical, environmental and industrial significance is described. The first, detailed in part I, is concerned with the evaluation of silver as a reductive amperometric detector electrode for HPLC. Three detector variants have been developed, utilizing silver in the form of a continuous silver disc, a segmented silver oxide grid assembly and in a differential arrangement. The dynamic properties of the three cells, i.le., the linear dynamic range, the reproducibility, and dependence on flow rate and electrode area were tested using a series of quinones and nitro-aromatics as model substances. The electrochemical detector (ECD) with the continuous electrode has a wide linear dynamic range, high sensitivity and an extremely rapid response time for analytes reduced at potentials anodic of ;Part II is concerned with the use of supercritical fluid extraction (SFE) for sample preparation. A simple laboratory-constructed system is described which allows quantitative and selective recovery of quinones and nitro-aromatics from complex matrices. Parameters such as temperature, pressure, modifier type and amount were optimized for maximum recoveries. Quantitative recovery of various quinones from carbon black samples was maintained down to 1-5 ;In part III, HPLC methods incorporating SFE sample preparation with ECD have been developed for the determination of anthraquinone in wood and paper pulp, nitrosoamines in powdered milk, vitamin K... |
