Product Description

NN is a colorimetric and chelatometric reagent for calcium (pH 12, λmax=470 nm) and UO₂²⁺ (λmax=570 nm, ε=1.36×10⁵). Although NN is soluble in water, the solution is unstable and decomposes in a few minutes, especially in the presence of oxidative ions. Its proton dissociation constants are reported to be pKa₂=9.26 and pKa₃=13.67 (μ=0.1, 24ºC). An NN solution of 0.1% w/v in 50% aqueous methanol is stable for one week if stored in a cool and dark place. Ascorbic acid is used as a stabilizer of the NN stock solution. Al, Cu, Fe(III), and Ni interfere with the determination of calcium by NN and should be masked by KCN or triethanolamine.

Chemical Structure