Study on S2 emission response from sulphones and sulphonic acids in molecular emission cavity analysis

In general, sulphones and sulphonic acids show low S2 emissivity in comparison with sulphides and thiols. The cause of the low sensitivity and a technique for enhancing the emission intensity are investigated in molecular emission cavity analysis. Sulphides and thiols are rapidly desulphurized with hydrogen, but sulphones and sulphonic acids vaporize or decompose slowly. The emission intensities of sulphones and sulphonic acids significantly decrease with increase in vaporization temperature of the compounds and tm values (the time at which an emission reaches maximum intensity after the cavity has been introduced into the flame). It is found that the direct flow of air to the cavity is effective for promotion of the vaporization of the compounds and enhances the S2 emission. It is suggested that low emissivity for sulphones and sulphonic acids is attributed to the difference in the vaporization process of the compounds rather than the strong S = O bond.