THE APPLICATION OF DIARYLAMINE COMPOUNDS IN ANALYTICAL-CHEMISTRY .1. FLUORESCENCE REACTIONS AMONG 4-(4-METHYL-2-QUINOLYL)AMINOSALICYLIC ACID, COBALT(II) AND HYDROGEN-PEROXIDE, AND THE FLUORIMETRY OF COBALT(II) BY USING ITS FLUORESCENCE REACTION

The fluorescence reactions among 4-(4-methyl-2-quinolyl)aminosalicylic acid (MQAS) as a diarylamine compound, hydrogen peroxide as an oxidizing agent, and various metal ions such as cobalt(II) were spectrofluorometrically investigated in the presence or in the absence of various surfactants. The MQAS-hydrogen peroxide solution in the presence of trimethylstearylammonium chloride (STAC) as a cationic surfactant was catalytically converted to a fluorescence product by the coexistence trace amounts of cobalt(II), and its relative fluorescence intensity at 400 nm in the fluorescence reaction product was proportional to the cobalt(II) concentrations. Moreover, a highly selective and sensitive fluorimetric method for the determination of cobalt(II) using MQAS and hydrogen peroxide in the presence of STAC in basic media was proposed. The calibration graph was linear in the range of 0 - 45 ng cobalt(II) per 10 cm3 at an emission wavelength of 400 nm, with an excitation wavelength of 320 nm.