Abstract: Linear-sweep anodic peaks of synthetic food coloring matters at a stationary carbon paste electrode have been found to be generally sharper, to be better resolved from the cut-off current and to have a lower base-line current than those obtained at a glassy carbon electrode. All of the food colors studied also gave cathodic peaks at a stationary glassy carbon electrode but there was fluctuation of peak potential and instability of peak shape with some colors. The cathodic peak potentials of the yellow food colors were particularly well separated. The more limited negative potential range available with carbon paste restricted study to ten food colors.The voltammetric waves of four food colors showed some reversibility when studied by cyclic voltammetry. The anodic peaks of the triphenyl-methane colors, Green S, Patent Blue V and Brilliant Blue FCF, show small peaks on the reverse scan. Indigo carmine is unique in having a large peak on the reverse scan of the cathodic peak.Carbon paste and glassy carbon electrodes used anodically in the wall-jet configuration have been shown to give good precision, rectilinear calibration graphs and low limits of detection for the determination of food colors by flow-injection analysis.

Abstract: The construction of a simple wall-jet detector cell, which can be used either with a solid electrode or with a sessile mercury-drop electrode, is described. The cell consists of two interlocking parts that hold separately the working electrode and the eluent inlet. The detector is used partly immersed in electrolyte solution to give contact with a counter and a reference electrode. Use of the cell is illustrated by determination of permitted synthetic food coloring matters at the 0.1 µg ml-1 level with both electrodes.

Abstract: This paper describes an improved instrument (DP90, Groton Technol., Acton, MA), the design of which was based on experience with the DP82. The DP90 can be used in a traditional manner in unstirred bulk solution or in flow streams as detectors for HPLC or FIA. It operates with a commercial PC as a host computer and features a real-time display of operating parameters and acquired data, the unique ability to change parameters repeatedly during an experiment, the capacity to store all data and parameter values, and the capability of compensating background currents on a point-by-point basis during voltammetric sweeps to allow increased gain in the instrument. (SFS)