Isotachophoretic Determination of Sulphite in Mustard

A capillary isotachophoretic (CITP) method of sulphite (free, bound and total) determination in mustard is described. A clear separation of the sulphite from other components of water extract of mustard paste was achieved within 20 min. Method characteristics, i.e., linearity (0–1250 mg of SO2/kg), accuracy (recovery >95%), precision (RSD=3%) and detection limit (6 mg/kg) were determined. Low laboriousness, sufficient sensitivity and low running cost are the important attributes of the CITP method. The developed method was successfully applied to analyses of real mustard samples and used for the determination of sulphite in mustard paste during its storage.