Parameter dependent ECNI-MS fragmentation of C10, C11, C12, and C13 polychlorinated alkanes

ECNI mass spectrometric fragmentation of chloroalkanes depends mainly on the degree of chlorination, but also on the chain length and ion source temperature. The interpretation of mass spectra is further complicated by the abundance of spectra of different mixtures obtained with the conventional HRGC-MS, which to compare is tedious and time-consuming. The recently developed short-column GC-MS method, which leads to the elution of all chloroalkanes of the mixture as one peak, can be used to obtain one single MS spectrum, which then may be more conveniently interpreted in comparison with the spectra of mixtures of defined chain length and chlorination degree. To obtain reliable results, the variability of the spectra in dependence on different parameters has to be taken into account. In this work, the MS fragmentation of several C10-C13 polychloroalkanes in dependence on chlorination degree, alkane chain length, and ion source temperature was investigated. The most intensive ion registered under ECNI conditions was either [M-HCl]^- or [M-Cl]^- depending on the chlorination degree or ion source temperature. It was also found that the low boiling compounds cannot completely be detected even at an ion source temperature of 250°C.