s-Benzylthiuronium PVC matrix membrane sensor for potentiometric determination of cationic surfactants in some pharmaceutical formulation.
The construction and characteristic performance of s-benzylthiuronium (s-BT)-PVC membrane sensor responsive for cetylpyridinium chloride (CPC) are described. The sensor is based on the use of s-BT-tetraphenylborate (TPB) ion pair as electroactive material in PVC matrix in presence of dioctylphthalate as solvent mediator. The membrane sensor shows a fast, stable and near Nernstian response for CPC over the concentration range of 6 x 10(-6)-1 x 10(-3)M at 25 degrees C and pH range 6-12 with cationic slope of 57.0+/-0.4. The lower detection limit is 4 x 0(-6)M and the response time is 10-30 s. Selectivity coefficients for CPC relative to a number of different species were investigated, which there is negligible intereferences are caused by most of investigated cations, anions, and some organic compounds. The determination of 2.0-350.0 microg/ml of CPC in aqueous solutions shows an average recovery of 98.8%and a mean relative standard deviation of 1.87% at 64.0 microg/ml. The determination of CPC in mouthwash pharmaceutical solution gave results that compare favorably with those obtained by the British pharmacopoeia method. The s-benzylthiuronium electrode has been utilized as an end point indicator electrode for some precipitation titration reactions involving CPC as titrant.
Microanalytical Laboratory, Applied Organic Chemistry Department, National Research Center, Dokki, Cairo, Egypt. gamal_most@yahoo.com
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Mostafa
D002594:Cetylpyridinium / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003902:Detergents / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D017736:Ion-Selective Electrodes; D008567:Membranes, Artificial; D010670:Phenylthiourea / Q000031:analogs & derivatives*; D011143:Polyvinyl Chloride; D011199:Potentiometry / Q000379:methods*; D013501:Surface-Active Agents / Q000737:chemistry*
D003902:Detergents; D008567:Membranes, Artificial; D013501:Surface-Active Agents; D010670:Phenylthiourea; D011143:Polyvinyl Chloride; D002594:Cetylpyridinium; C037877:benzylthiourea