A sequential injection analysis system for potassium clavulanate determination using two potentiometric detectors.

Two almost independent potentiometric methods were implemented in a multi-task flow system based on the concept of sequential injection analysis for the analytical control of potassium clavulanate in pharmaceutical formulations. In addition to in-line preparation of the solutions submitted to the analysis, the system simultaneously detected the clavulanate anion and the potassium cation using two potentiometric detectors selective to each of the species referred. For the two determinations, the system developed presented an analytical range of 2 mM-0.1 M. Relative standard deviations of 0.5 and 0.6%, respectively, for clavulanate and potassium, were calculated from the signals obtained for 10 consecutive injections of a solution of 5x10(-3) M potassium clavulanate. The frequency of sampling was 53 samples h(-1). The quality of results supplied was evaluated by comparison with the reference procedure revealing relative errors less than 2% for the two determinations. The simultaneous attainment of two measurements permitted the standardisation of results in real time, the detection of faults in the procedure and monitoring the chemical stability of clavulanate.