DIMETHYLGLYOXIME DOPED SOL-GEL CARBON COMPOSITE VOLTAMMETRIC SENSOR FOR TRACE NICKEL

A new class of modified sol-gel carbon composite electrodes, based on the encapsulation of complexing ligands, is described. Such modified e lectrodes couple the versatility and tunability of sol-gel processes w ith the advantages of the preconcentration/voltammetric strategy. The incorporation of the ligand dimethylglyoxime (DMG) within the carbon-s ilicate ceramic network is used to illustrate the new concept in conne ction with the voltammetric sensing of trace nickel. The sol-gel carbo n composite serves as a favorable host matrix for DMG, which retains i ts nickel binding characteristics. Factors influencing the sensor resp onse, including the sol-gel hydrolysis time, DMG loading or preconcent ration time are explored. The electrode displays good linearity up to 800 mu g/L nickel, a detection limit of 15 mu g/L (following a 5 min a ccumulation), and a relative standard deviation of 7.7%. Applicability to assays of river water is illustrated. Doping of other ligands into sol-gel carbon composites should result in similar voltammetric senso rs for other important metals.