Tubular detectors for flow-injection potentiometric determination of tetrafluoroborate in electroplating baths

Abstract

PVC tetrafluoroborate tubular electrodes without an inner reference solution, based on tetraoctylammonium as the ion exchanger and 2-nitrophenyloctyl ether as the mediator solvent, were constructed. The general operating characteristics of the tubular detectors were evaluated by a single line flow-injection system with low sample dispersion and compared to those of corresponding conventionally-shaped electrodes, determined in batch conditions. In flow-injection analysis (FIA), the detector response was linear in the concentration range between 4 × 10 −6 and 10 −1 M, with a mean slope of 59.2 ± 0.9 mV/dec in the pH range between of 2.7 and 11.5 The reproducibility of the detector potentials was approximately 0.2 mV during a day of continuous operation. The membrane used showed a high degree of selectivity. The tubular detectors remained operational over a long period of time (approximately 36 months) and had a response time that enabled a sampling rate of 360 h −1. The electrodes were later used in the determination of tetrafluoroborate in concentrated electrolytic baths for which a high dispersion FIA system was developed. The analyses of seven baths with different compositions presented results with mean recovery values of 98.8% with a coefficient variation of 1.9%.