Estimation of Tb³⁺ by mellitic acid sensitized luminescence in methanol

Abstract

Mellitic acid sensitized luminescence of Tb³⁺ in methanol exhibits a strong emission which is about 500 times more intense than that observed in water. Under optimal conditions, the luminescence intensity exhibits an excellent linear relationship in the concentration range of 5 × 10^-10–5 × 10^-8 <em>M</em> with a detection limit of 3 × 10^-11<em>M</em>. The interferences due to other lanthanides have been examined and found to be tolerated up to about 100-fold excess and hence estimation of Tb³⁺ in the presence of excess of lanthanides is possible. This method has been applied to the estimation of Tb³⁺ in simulated rare earth and tap water samples and the result is comparable to the result obtained from ICP-MS. Mechanism of enhanced luminescence is also proposed. This is the first report where mellitic acid sensitized luminescence is applied for the estimation of Tb³⁺.