Dependence of GC-RRTs on the electrical charge at substituents of chlorinated dioxins and related compounds

The correlation between gas chromatograph relative retention times (GC-RRTs) of polychlorinated dioxins and related compounds (PCBs, PCDDs, PCDFs, and PCNs) and descriptors calculated from the electrical charges at substituents, such as the sums of the charges at hydrogen atoms (QH), and chlorine atoms (QCl), and the sum of QH and QCl (Qall), was analyzed for their congeners and isomers. The dependence of GC-RRTs on these descriptors varied dramatically. For the congeners, there was an approximately linear relationship between GC-RRTs and all the descriptors. For the isomers, although there was little significant relationships, by classifying GC-RRTs based on Nad-Cl or Nad-H defined from the number of adjacent chlorine and hydrogen substituents, a linear relationship between GC-RRTs and QH was found for CBs, CDDs, and CDFs, and GC-RRTs for CNs could be classified. From an analysis of the electrical charges at hydrogen substitutents bonded to adjacent and non-adjacent positions, the average-charge of such substituents bonded to adjacent positions decreased with an increase in Nad-H, and this tendency was similar to that for bonding to ortho-, meta-, para-, α-, and β-positions.