Simultaneous determination of Fe(II) and Fe(III) in waters by capillary isotachophoresis

An ITP method for the simultaneous determination of Fe(II) and Fe(III) in w aters, based on separation of their EDTA and fluoride complexes, respective ly, was developed. The leading electrolyte used consists of chlorides, La(I II) as co-counter ion and is buffered with p-alanine to pH = 3.5. The termi nating electrolyte contains caproic acid and L-histidine (pH = 4.5). The me thod was validated and tested with samples of artificial, ground and treate d water with good results, comparable to those obtained by other analytical techniques. Fe(II) and Fe(III) up to 20 mg/L were measured with an RSD = 1 .4-1.5% and detection and determination limits of 0.8-0.9 and 3.0-3.5 mg/L, respectively. The ITP method can be recommended for routine utilization in hydroanalytical laboratories.