Behaviour of different eluents and stabilizing agents in the determination of sulphite in water by ion-chromatography

Ion-chromatography has been used for the determination of sulphite in water. The eluents were solutions of Na(2)CO(3) (1.1mM)-NaHCO(3) (1.4mM) or NaHCO(3) (1.0mM)-formaldehyde (0.2% w/w), and formaldehyde, glycerol or fructose was used as stabilizing agent. With the first eluent, fructose or glycerol can be used to stabilize samples against sulphite oxidation, but formaldehyde affects the peak height. On the other hand, formaldehyde can stabilize sulphite in the presence of Fe(III), whereas glycerol and fructose can not. If Fe(III) is present, the second eluent is used and sulphite is eluted directly as hydroxymethanesulphonate; formaldehyde will not then affect the peak height. This eluent allows a good peak separation and is suitable for the sulphite concentration range 0.1-12.0 mg/l.