Potentiometric membrane sensor for determination of saccharin

A potentiometric poly(vinyl chloride) membrane sensor for determination of saccharin is described. It is based on the use of Aliquat 336S-saccharinate ion-pair as an electroactive material in plasticized PVC membranes with o-nitrophenyloctylether or dioctylphthalate. The sensor is conditioned for at least two days in 0.1mol L-1 sodium saccharinate before use. It exhibits fast, stable and Nernstian response for saccharinate ions over the concentration range of 1.0 x 10(-1) - 5.0 x 10(-5) mol L-1 and pH range of 4.5-11. The sensor is used for determination of saccharin in some dosage forms. Results with an average recovery of 101\% and a mean standard deviation of 0.2\% are obtained which is compared favourably with data obtained using the British pharmacopoeia method. The sensor shows reasonable selectivity towards saccharin in presence of many anions and natural sweeteners.