Sulphanilic

The main aim of this method is measurement of wave length of azo-dye which is formed by the reaction of 1-naphthylamine with diazonium salt, formed by the reaction of sulphanilic acid with nitrous acid (Figure 2A) [43].

Sodium sulfate, acetone, alcohol, sulphanilic acid, sodium nitrite, trisodium phosphate was purchased from S.D.

Keliher, "Spectrophotometric determination of nitrite with composite reagents containing sulphanilamide, sulphanilic acid or 4-nitroaniline as the diazotisable aromatic amine and N-(1-Naphthyl)ethylenediamine as the coupling agent," Analyst, vol.

This study reports a simple FI spectrophotometric method for the determination of ANTU in natural waters, based on the conversion of nitrite into nitrous acid, subsequent diazotization of sulphanilic acid, and formation of the diazonium salt.

This is a method by which bilirubin reacts with diazotised sulphanilic acid to produce azobilirubin (Violet colour).

A number of methods have been reported for the synthesis of 3,4-dihydropyrano[c]chromenes with the catalysts such as pyridine [10], [K.sub.2]C[O.sub.3][11], diammonium hydrogenphosphate [12], MgO [13], TBAB [14], Si[O.sub.2]PrS[O.sub.3]H [15], 4-(dimethylamino)pyridine (DMAP) [16], trisodium citrate [17], ammonium acetate [18], polymer supported sulphanilic acid [19], basic ionic liquid [20], CuO nanoparticles [21], p-dodecylbenzenesulfonic acid [22], amberlyst A21[23], silica-grafted ionic liquid [24] Ti[O.sub.2] [25], thiourea dioxide [26], [Fe.sub.3][O.sub.4]@SiO2-imid-PMAn nanoparticles [27], and A,A-dimethylbenzylamine (DMBA) [28] have also been reported to promote this reaction.

After incubation, 5 drops of both reactive 1 ([alpha]-naphthylamine 1 g, distilled water 22 ml, heat solution, filter, and then adding acetic acid 1 ml) and reactive 2 (sulphanilic acid 0.5 g, diluted acetic acid 150 ml) was added in the tube.

Separation was performed with acetonitrile/ methanol/water (1:1:1) as a solvent system and visualized by short wave length (245 nm) and diazotized sulphanilic acid.