Spectral study of the interaction between 2-pyridinecarbaldehyde-p-phenyldihydrazone and ferric iron and its analytical application.

The synthesis and spectral characterization of a schiff base, 2-pyridinecarbaldehyde-p-phenylenedihydrazone (short for 2PC-PPH), were described. It was found that ferric ion (Fe(3+)) could selectively quench the fluorescence of 2PC-PPH, whereas many other metal ions, such as Mn(2+), Zn(2+), Cu(2+), K(+), Al(3+), Ca(2+), Ni(2+), Co(2+), Cr(3+) and Fe(2+), could not quench its fluorescence. Based on this, a sensitive method for ferric ion selective detection was established. Under the optimum conditions, the decreasing fluorescence intensity of 2PC-PPH is proportional to the concentration of Fe(3+) within the range of 6.0×10(-7)-1.0×10(-5) mol L(-1). The detection limit (3σ) for Fe(3+) determination is 3.6×10(-7) mol L(-1). The proposed method was successfully applied to determine iron in tea and milk powder.