Abstract: Samples of acids (15 µL) were injected into a stream of water which was merged with a stream of 2 M NaI and 50 mM NaIO3 (2.4 mL min-1). The detector placed 10 cm from the merging point was a flow cell containing two 8-mm x 0.3-mm diameter platinum electrodes at a constant polarizing voltage of 100 mV. Rectilinear graphs of concentration. vs. current were obtained for 1 to 10 mM acid and, with online microcomputer data processing, a coefficient of variation <0.2% was achieved.

Abstract: An automated flow injection system for online monitoring of monochloroacetic acid (I) in industrial processes for the prodn. of zwitterionic surfactants (betaines) was developed, which can treat samples with chloride ion concentration. up to 1 M. The system features an ion-exchange column for the separation of I from the interfering compounds in the complex sample. The sample is injected at low pH so that interfering anions, mainly Cl-, are retained in the ion-exchange column. Detection was carried out using specially constructed all-solid-state tubular flow-through ion-selective electrodes sensitive to monochloroacetate. Selectivity data of the constructed electrodes were given; their pH working range was 4.0-11.0, with a lifetime of >30 days at a concentration. of 10^-4 to 10^-1 M. Once applied to the treatment of real samples, the system developed can detect I at concentrations. 5 x 10^-3 - 10^-1 M, with a max. deviation of 5% when compared to standard photometric methods of anal. The short time used in each determination (30 s) in addition to its simplicity, leads to an improvement of available anal. techniques.