Automated system for performing pH-based titrations

Abstract

Liquid delivery and endpoint determination during titrations may be problematic if an analyst does not have adequate training or formal education. This can lead to issues with method accuracy and precision. This work is focused on the development of a simple, low-cost, automated system capable of performing potentiometric titrations with a push of a button. A single-board computer (Raspberry Pi), a stepper motor-based syringe pump, and a commercially available pH sensor circuit board were the primary components used to construct the auto-titrator system. Open-source Python programming language was used to control and coordinate components and provide a simple-to-use graphical user interface. A standard alkalinity method for drinking and raw water was evaluated and yielded an accuracy (recovery) between 92% and 104% for concentrations above 10 mg L−1. The precision of the method was less than 5% regardless of concentration. The developed titrator was tested at Lebanon, TN, and Woodruff, SC water treatment plants. The system was also certified by LabtronX to perform alkalinity measurements in Lebanon, TN, and served the plant operators for the past two years.