Determination of Partially Hydrolyzed Polyacrylamide with NH₃-Selective Electrode

It was found that the sensibilized NH3-selective electrode (NH3-ISE) was suitable to be used in the dynamic monitoring of the concentration of partially hydrolyzed polyacrylamide (PHPA) in the process of petroluem recovering for its high selectivity and precision. The sample was digested as in the Kjeldahl method for determination of nitrogen,and amide group in the PHPA molecule was transformed into NH+4 ion by the action of sulfuric acid. Sodium hydroxide solution was added to the sample solution to adjust the pH of the solution to around 11,and the NH+4 was converted to NH3 and detected by the NH3-ISE. The optimum range of PHPA to be determined by this method was found as from 6.00-45.00 mg·L-1,where the RSD′s found were less than 4.1%. Almost all of the inorganic ions do not interfere or only interfere slightly in this determination. But significant interferences were observed by volatile amines. The proposed method was also suitable to be used in the analysis of deionized water and mineral water.