Effects of temperature and sample amount on the electron capture negative ion mass spectra of polychloro-n-alkanes.

Article abstract of DOI:10.1016/S0045-6535(98)00130-1

Ion source temperature, sample amount and the positions of the chlorine atoms attached to the neutral molecule all had profound effects on the appearance of the ECNI mass spectra of a number of synthesized polychloro-n-alkanes (PCAs). Increases in the ion source temperature resulted in a decrease in the abundances of both the [M + Cl]^- and [M - Cl]^- ions, while the abundances of the structurally non-characteristic ions, HCl₂^- and Cl₂^-, increased. An increase in the amount of the injected PCA resulted in an increase in the abundance of the [M + Cl]^- ion, most notably for congeners containing chlorine atoms only 1,2-substituted at both ends of the alkane chain. The abundance of the [M - Cl]^- ion increases with decreasing ion source temperature down to 120°C, the lowest temperature easily maintained with our instrument. For analytical purposes we recommend that this source temperature be used.