Study of isotachophoretic separation behaviour of metal cations by means of particle-induced X-ray emission VI. Selective separation of twenty metal cations using tartaric acid as a completing agent

Abstract

The selective isotachophoresic (ITP) separation of twenty metal ions that form kinetically labile complexes with tartaric acid was investigated. The leading electrolyte was 20 m M ammonia solution buffered by adding acetic acid (pH 4.8) and the concentration of tartaric acid ( C Tar) was varied in the range 0–5 m M. The terminator was 20 m M carnitine hydrochloride solution. Isotachophoretic qualitative indices ( R E ) of the metal ions were measured by using a high-frequency contactless conductivity detector. An equimolar test mixture was separated by using a micro-preparative apparatus and the fractions were analysed off-line by particle-induced X-ray emission method (ITP-PIXE). When C Tar = 1 m M, the separability was good on average. The migration order was Ba 2+, (Sr 2+, Na +), Ca 2+, Mg 2+, Mn 2+, Fe 2+, Co 2+, Cd 2+, (Ni 2+ , Li +), Zn 2+, La 2+, (Ce 3+, Pb 2+), Y 3+, Gd 3+, Lu 3+, Cu 2+, where the ions in parentheses were not separated. Zr IVO 2+ was not detected. With increase in C Tar, the number of detectable elements decreased owing to the decrease in the effective mobilities of the separands. When C Tar = 5 m M, the migration order was Na +, Ba 2+, Sr 2+, Mg 2+, Li +, Ca 2+, Mn 2+, Cd 2+, CO 2+, Ni 2+ and Zn 2+. A model waste from a nuclear fuel was successfully analysed using the electrolyte system.