TRIANGLE PROGRAMMED COULOMETRIC FLOW TITRATION WITH POTENTIOMETRIC AND OPTICAL-DETECTION

The application of a flow-through titration technique, the so-called triangle programmed coulometric titration, is presented for acid-base titrations using potentiometric and photometric detection. A flow-through capillary glass electrode-saturated calomel electrode pair was employed for potentiometric detection, and an indicator mixture and a light-emitting diode-phototransistor system was used for photometric detection. In photometric detection the precision of the end-point location was enhanced by the addition of a suitable mixture of Methyl Red and m-Cresol Purple acid-base colour indicators. The suitability of the technique was demonstrated for different acid-base titrations. As an example, the determination of the drug content of a nicotinic acid-containing experimental pharmaceutical preparation is described.