Abstract: A simple mathematical treatment is applied to the instantaneous acid - base equilibria prevailing at the peak maxima for acid - base indicators when used as reagents in spectrophotometric flow injection determinations. Equations are derived relating the absorbance, the fraction of the relevant form of the indicator and the rate of change of either form with the initial concentration. of the analyte and other relevant parameters. Criteria are set for the choice of reagent/indicator combinations likely to yield rectilinear absorbance/concentration. dependence for general and special instances. Suitable conditions are described for the determination of HCl, H3PO4, acetic acid, NaOH and ethanolamine. Least-squares treatment of data yielded coefficient of variation of 0.5% over a reasonably wide concentration. range. The highest throughput of samples achieved was 144 h-1.

Abstract: Ethanolamine, diethanolamine and triethanolamine are separated by ion-pair chromatography on an ODS column and detected by their suppressive effect on the copper(II)- or cobalt(II)-catalyzed chemiluminescence emission from the luminol reaction. Post-column reaction conditions were simplex optimized using a flow injection manifold. Limits of detection (twice the peak-to-peak noise) for ethanolamine, diethanolamine and triethanolamine was 0.8, 1.2 and 0.2 nmol, respectively.