I analyse Effluent for Anions(Ion Chromatography). Recently, the Sulphate peak has been displaying a jagged tip. Retention time is consistent, as are peak height and area. This issue is exclusive to the Sulphate peak. Anyone any ideas.

I need a bit more information to make an assessment. Do you mean that the top of the sulfate peak is jagged (i.e. your data system is detecting multiple peak maxima) or do you mean the tail of the peak (or the front of the peak) is jagged. Also, it would be helpful to know which instrument, column, detector, eluent system and suppressor you are using (assuming you are using a suppressor).