A new quaternary luminescence enhancement system of Eu–N-(3-methoxysalicylidene)-2-aminopyridine–1,10-phenanthroline–Zn and its application in determining trace amounts of Eu3+ and Zn2+

A new sensitive quaternary luminescence enhancement system was developed successfully to determine the trace amounts of Eu3+ and Zn2+. The luminescence intensity of Eu–N-(3-methoxysalicylidene)-2-aminopyridine system was greatly increased by the addition of 1,10-phenanthroline and Zn2+. The excitation and emission wavelengths were 274 and 617 nm, respectively. Under optimal conditions, the luminescence intensity of the system showed a linear response toward Eu3+ in the range of 6.0 × 10−6–2.5 × 10−5 mol L−1 with a detection limit of 2.0 × 10−9 mol L−1. This method was successfully applied for the determination of trace amounts of Eu3+ in a high purity Gd2O3 matrix and a synthetic matrix. In addition, it was found that under optimal conditions, the luminescence intensity of the system decreased linearly with the increase of Zn2+ concentration, ranging from 2.0 × 10−6 to 1.8 × 10−5 mol L−1 with a detection limit of 2.8 × 10−8 mol L−1. This method was also successfully applied to determine the trace amounts of Zn2+ in a high purity Mg(NO3)2·6H2O matrix and a synthetic sample. The interferences of other lanthanide ions and some common coexisting ions were investigated. The mechanism for energy transfer and luminescence enhancement of this quaternary system was also studied systematically.