Asymmetric porphyrin derivative having one reactive site as a highly sensitive spectrophotometric reagent for nitrite

The asymmetric porphyrin derivative having only one reaction site, A1Py3P [5-(4-aminophenyl)-10,15,20-tris(4-pyridyl)porphine], was synthesized [ϵ=2.1×105 M−1 cm−1 (pH 1.0, at 441 nm)]. UV, IR and mass spectral measurements, elemental analysis and thin layer chromatography were carried out for identification of A1Py3P. It was demonstrated that the porphyrin reacted with nitrite in a mole ratio of 1 : 1, giving a useful spectral change. The spectrophotometric determination of nitrite using A1Py3P was excellent with respect to calibration linearity: 0–8.0×10−7 M, detection limit (3σ): 7.0×10−9 M, relative standard deviation: 1.0%, for 10 determinations at 4.0×10−7 M.