Saburo Nakano

Fluorometric Determination of Some Primary Aromatic Amines with 4-Methoxy-m-phenylenediamine

A sensitive fluorometric method for the determination of primary aromatic amines is described. The procedure consists of diazotization of the amino group followed by coupling with 4-methoxy-m-phenylenediamine (MPD), and reaction of the resulting azo compound with ammoniacal cupric sulfate. By this reaction, primary aromatic amines are derivatized to intensely fluorescent compounds, and a method for the determination of p-aminobenzoic acid (PABA) was established. A linear relationship was observed between the PABA concentration and the fluorescence intensity in the range of 0.001-1.0 μg/ml. The proposed method is applicable to the determination of other primary aromatic amines.

2(1H)-quinolinethione derivatives as organic reagents. II. Properties of some 2(1H)-quinolinethione derivatives and application to the potentiometric titration of the silver ion.

Halogen derivatives of 2 (1H)-quinolinethione, alkyl derivatives of 1, 2-dihydro-2-thioxo-4-quinolinecarboxylic acid, and alkyl 1, 2-dihydro-2-thioxo-4-quinolinecarboxylate were synthesized. The detection limits for metal ions with these reagents were examined by spot tests. The metal ions which gave a precipitate with these reagents were the same as those reported previously. iso-Amyl 1, 2-dihydro-2-thioxo-4-quinolinecarboxylate (ATQ) forms a 1-to-1 compound with silver, and an ethanolic solution of ATQ was used as a titrant to determine 0.01-0.0001 M silver ions potentiometrically. The coefficient of variation was 1.8% (n=10) for 107.4 μg of silver. Silver protein was titrated potentiometrically with ATQ in 50% (v/v) ethanolic solution. The silver content was 8.0%, with a coefficient of variation of 1.8% (n=5).