Separation and determination of aniline and substituted anilinesulphonic acid derivatives by ion-pair reversed-phase high-performance liquid chromatography

A high-performance liquid Chromatographie ion-pair reversed-phase method using tetrabutylammonium hydrogen sulphate (TBAHS) has been developed forthe separation and determination of orthanilic, metanilic, sulphanilic, phenylsulphamic, aniline-2,4-disulphonic, aniline-2,5-disulphonic, aniline-2,4,6-trisulphonic, 4-sulphophenylsulphamic acids and aniline in spiked solutions and in concentrated H₂SO₄ sulphonation mixtures. Several acetonitrile - water eluents were evaluated and the most suitable was that containing 5% acetonitrile, 0.05 M Na₂HPO₄ and 0.005 M TBAHS at a pH of 5.5, used with a Spherisorb 10 ODS column. Aniline-2,4,6-trisulphonic acid did not elute under these conditions and therefore a 15% acetonitrile - water solvent system, pH 6.5, was used to elute this compound. The method reported here offers several major advantages over previously used methods. These include (i) separation and determination of all nine compounds in the same solution in two operations, (ii) no mutual interference between the compounds, (iii) high precision of analysis and detection at low levels and (iv) convenience and speed of analysis.