US Patent 4,735,692
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
A novel ion-selective membrane electrode for the determination of phosphate anions. This device possesses an excellent selectivity for phosphate over many common anions such as sulfate, chloride, bromide, iodide, nitrate, and acetate. The unique feature of this electrode is the use of a di-substituted aryl tin compound as the membrane active material. The incorporation of either dibenzyltin dichloride or bis-p-methylbenzyltin dichloride in a plasticized poly(vinyl) chloride membrane results in a selective membrane electrode for phosphate.
Arnold, Mark A. and Glazier, Scott A. Phosphate selective membrane electrode and method of determining phosphate. US Patent 4,735,692 filed April 08, 1987 and issued April 05, 1988. https://ir.uiowa.edu/patents/56