Chelating agent. Prepn: H. Schl"apfer, J. Bindler, US 2709178 (1955 to Geigy). Toxicology: J. E. Wynn et al., Toxicol. Appl. Pharmacol. 16, 807 (1970). Thermal properties: M. F. G. Esteban et al., Thermochim. Acta 62, 267 (1983). Cathodic-stripping determn: M. Ciszkowska, Z. Stojek, Talanta 33, 817 (1986). Use in calcium measurements: J. D. Johnson et al., Am. J. Physiol. 272, C1437 (1997); in heavy metal remobilization from river sediment: K.-C. Yu et al., Toxicol. Environ. Chem. 58, 85 (1997). Review of regulation of Ca+2 concentration in biological systems: S. Robertson, J. D. Potter, Methods Pharmacol. 5, 63-75 (1984).