Regularities of Ionization of 92 Industrial Dyestuffs by Q-Orbitrap-High Resolution Mass Spectrometry

A probe into the regularities of ionization of molecular ion peaks of 92 industrial dyestuffs was accomplished by Q-orbitrap-high resolution mass spectrometry in the analytical mode of full scanning of positive and negative ions with rapid switching. It was found that the existing forms of molecular ion peaks of basic dyestuffs were determined by the existing forms of the elements of chlorine or sulfur in the molecules of the dyestuffs. Cl-containing basic dyestuffs with chlorine present as hydrogen chloride formed molecular ionic peaks of^*M+H^- by giving up hydrogen chloride, Cl-containing basic dyestuffs with chlorine present as chloride, and having strongly polar groups (N in the molecule appears in positive ionic state having 4 valency bonds) formed molecular ionic peaks of^*M⁺ by giving up their Cl^-. For S-containing basic dyestuffs with sulfur present as HSO₄^-, and having also the strong polar groups of N⁺ as above, their molecular ionic peaks transformed into^*M⁺ by giving up the HSO₄^- ion. For acidic dyestuffs, forms of their quasi-molecular ionic peak were related to the numbers of Na⁺ and sulfonate group in their molecules, and were tending to give up all the Na⁺ ions and to combine the H⁺ from the solvent to the sulfonate radicals, forming a series of anions conforming to the formula(M-xNa+yH)/(x-y)^-, and giving mainly divalent quasi-molecular ionic peaks for dyestuffs containing 2 and more sulfonate radicals. Dispersed dyestuffs and sudan dyestuffs were weakly polar dyestuffs containing electronegative groups and were tending to form molecular ionic peaks ofM+H⁺ more easily.