POTENTIOMETRIC GAS-SENSING PROBE FOR THE SELECTIVE DETERMINATION OF ACETATE ION

A novel potentiometric sensor for simple, sensitive, and selective determination of acetate ion is developed and electrochemically evaluated. This assembly is based on the use of a flat-bottom combination glass pH electrode behind a Teflon membrane and in contact with a thin film of sodium acetate-sodium chloride internal electrolyte solution. Acidifying the analyte acetate solution to pH <2 allows the free acetic acid vapor to diffuse through the membrane and changes the pH of the electrolyte, which is monitored by the pH electrode. The nature and origin of sensor response, response time, potential stability, influence of membrane type, effect of foreign ions, electrolyte osmolality, effect of pH, and effect of temperature are examined. Under optimized conditions, the sensor displays a rapid, stable, and Linear response for a logarithmic concentration of 10(-1)-10(-5) M acetate with a cationic slope of 59.2 +/- 0.3 mV (concentration decade)(-1). The lower limit of detection is similar to 0.6 mu g mL(-1). The sensor is successfully used for accurate determination of acetate in some medical solutions, metal acetates, and vinegar.