- Isotachophoretic separation behavior of rare-earth EDTA chelates and analysis of minor rare-earth elements in an iron ore by bidirectional isotachophoresis-particle-induced X-ray emission. Hirokawa, T., Nishimoto, K., Jie, Y., Ito, K., Nishiyama, F., Ikuta, N., Hayakawa, S. Journal of chromatography. A. (2001)