Table 1 summarized the obtained results. The tolerance concentration was taken as the maximum concentration of the foreign substances that caused an approximately ±5% relative error in the determination. The tolerated ratio of the foreign substances was 200 for Na+, NH4 +, Cl−, NO3− and CO3 2 −; 50forK+ and I−and 25 for uric acid. As can be seen, these species did not interfere which shows the extent of selectivity of the proposed method for the determination of BPR.