[Determination of trace manganese by catalytic kinetic spectrophotometry method with CTMAB as the sensitizer].

A new catalytic spectrophotometric method for the determination of trace amount of Mn(II) was developed. The method is based on the oxidation of 7-(2-nitryl-4-methyl phenylazo)-8-hydroxy-qinolin-5-slfonic acid by potassium periodate in the presence of nitrilo triacec acid as an activator and CTMAB as a sensitizer. The wavelengths for the determination was 509 nm. The linear range of determination is 0-3. 2 x 10(-9) g x mL(-1) for Mn(II). The determination limit is 3.8 x 10(-11) g x mL(-1). The interference of foreign ions was studied. The method can be used for the determination of Mn(II) in mung bean, rice, cereal and soil samples.

[Fluorescence property of OBBE and its application].

The effects of acidity and temperature on the fluorescent characteristics of N-N-bis-(O-Carboxylphenyl)-Oxamide (OBBE) have been studied in details. And the quantum efficiency of fluorescence has been measured. In a pH 8-9.5 buffer medium of H3BO3-NaOH, OBBE has a maximum excitation wavelength at 210 nm and a maximum emission wavelength at 395 nm. The nitrate reacts with OBBE and quenches the fluorescent intensity of OBBE. Thus a new sensitive method using the quenching of synchronous fluorimetry has been developed for the direct determination of nitrate in water. The linear calibration curve was obtained in the range of 0.0028 and 0.16 mg.L-1, the detection limit was 0.0028 mg.L-1. The proposed method has been applied to the determination of nitrate in water with satisfactory results.