Cation chelant; reacts with metal ions to form stable, intensely colored complexes. Prepn: A. Tschitschibabin, M. Rjasanzew, Chem. Zentralbl. 1916, III, 228. Improved synthesis: S. Wiejak et al., Pol. J. Chem. 58, 895 (1984). Spectroscopy studies of PAN and its metal chelates: D. Betteridge, D. John, Analyst 98, 377, 390 (1973) DOI. Electronic absorption spectra: M. S. Masoud, H. H. Hammud, Spectrochim. Acta A 57, 977 (2001) DOI PubMed. Metal ion extraction applications: J. Gao et al., Talanta 40, 195 (1993) DOI; I. Narin, M. Soylak, ibid. 60, 215 (2003) DOI; M. Tuzen et al., Anal. Lett. 37, 473 (2004) DOI.