Determination of melamine in different milk batches using a novel chemosensor based on the luminescence quenching of Ru(II) carbonyl complex

A novel, simple, sensitive and precise spectrofluorimetric method was developed for measuring the melamine concentration in different milk batch samples. The method was based upon measuring the quenching of the luminescence intensity of the produced yellow colored ruthenium(II) carbonyl complex of the general formula [Ru(CO)2(L)] (where L = anion of tetradentate Schiff base). The Ru(II) complex exhibited characteristic luminescence band in the visible region. The remarkable quenching of the luminescence intensity of [Ru(CO)2(L)] complex by various concentrations of melamine was successfully used as a chemosensor for the assessment of melamine in different milk samples at λex = 400 nm and pH 7.4 in DMSO with a linear dynamic range 1.0 × 10−6 to 3.0 × 10−9 mol L−1 and lower detection limit (LOD) and quantification detection limit (QOD) of 3.3 × 10−10 and 1.0 × 10−9 mol L−1, respectively.