CONSTRUCTION AND EVALUATION OF TETRAFLUOROBORATE SELECTIVE ELECTRODES- APPLICATION TO PLATING BATHS ANALYSIS

The construction and evaluation of three types of tetrafluoroborate el ectrodes without internal reference solution is described. Sensors for electrodes of Type A and Type B use tetraoctylammonium tetrafluorobor ate as carrier and 2-nitrophenyloctylether and dibutylphthalate, respe ctively, as solvent mediators. Electrodes of Type C use the 99-05-02 O rion commercial sensor based on a complex of tris(1,10-phenanthroline) -Ni(II) dissolved in p-nitrocymene. Membranes were applied on a conduc tive support consisting of a mixture of graphite with a non-conductive epoxy resin. The three types of electrodes showed a similar behaviour with linear responses within the concentration range 10(-5) - 10(-1) mol/l in tetrafluoroborate, with slopes of 58 mV per decade when the p H of the solutions was between 3 and 11.5. Electrodes of Type A showed the lowest short term hysteresis after treatment with interfering spe cies and offered the best reproducibility and lifetime. Therefore, the y were used in the determination of tetrafluoroborate ion in plating b aths by means of the sample addition method, giving results with an av erage spike recovery of 100.5% and a mean coefficient of variation of 1.0%.