Luminescent properties of magnesium and calcium 8-hydroxyquinolinates

The dependence of the luminescence intensity of magnesium and calcium 8-hydroxyquinolinates obtained on the paper surface on the type of buffer solution and solvent for 8-hydroxyquinoline was studied. The detection limit of magnesium and calcium cations in an aqueous solution was established: for Mg$^{2+}$ – 77.8 $\mu$g/ml (the highest luminescence intensity was established in an ammonia buffer solution when using a solution of 8-hydroxyquinoline in chloroform); for Ca$^{2+}$ – 252.2 $\mu$g/ml (the highest luminescence intensity was established in a tetraborate buffer solution when using a solution of 8-hydroxyquinoline in ethanol). Regression equations were obtained that make it possible to determine the concentrations of cations (Mg$^{2+}$, Ca$^{2+}$) in the solution depending on the luminescence intensity.