Determination of gaseous acidic compounds by measuring fluorescence after their reaction with tetra-substituted amino aluminum phthalocyanine

Based on the fluorescence enhancement of a red-region fluorescent dye, tetrasubtituted amino aluminum phthalocyanine (TAAlPc), in strongly acidic medium, a new method was developed for the detection of four strong acids (HCl, HBr, HNO₃ and H₂SO₄). Under optimal conditions the linear ranges of the calibration curves were 0.04-0.67 mol/1 (HCl), 0.04-0.67 mol/1 (HBr), 0.04-0.80 mol/1 (HNO₃) and 0.02-0.80 mol/1 (H₂SO₄), respectively. The detection limits were 0.007 mol/1 for HCl, 0.006 mol/1 for HBr, 0.005 mol/1 for HNO₃ and 0.007 mol/1 H₂SO₄. This method has been applied to the analyses of four artificial samples with satisfactory results.