Ion-molecular reactions in the negative ion laser mass spectra of aromatic nitro compounds

Abstract

Negative Ion laser mass spectra of many aromatic nitro compounds show formation of an Ion corresponding to ( + 0 -H)™ formed by an Ion-molecule reaction. It was established that Interaction of N02™ with neutral molecules Is responsible for formation of ( + O -H)". The presence of substituents like -Cl and -S03~I n aromatic nitro compounds leads to formation of ( + 0 -Cl)™ and ( + 0 -S03Na)~, respec-

Rapid determination of trace nitrophenolic organics in water by combining solid-phase extraction with surface-assisted laser desorption/ionization time-of-flight mass spectrometry

“…The SPE‐SALDI analysis was performed as described in the Experimental section. The electron‐withdrawing nitro groups on the aromatic ring promote the formation of the phenoxide pseudo‐molecular ion, [M − H] − , by increasing the hydroxide group acidity 21. The phenoxide ion mass peaks, at m/z 138, 183, and 228, respectively, are marked with an asterisk in each spectrum in Fig.…”

Speciation of Arsenic Oxides Using Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

“…Arsenic pentaoxide formed a greater variety of positive and negative ions than arsenic trioxide, which may be due to decomposition of the pentaoxide during vaporization. [33][34][35] Mixtures of Arsenic(III) and -(V) Oxides. The negative ion mass spectra demonstrate a more diverse set of clusters unique to each arsenic oxide than the positive ion mass spectra.…”

“…32 Negative ions are formed by either electron attachment or by ion-molecule reactions. 33 Simultaneous laser desorption and ionization at 266 nm of the arsenic oxides produces dominant cluster and fragment ions containing different ratios of arsenic and oxygen.…”

“…Ionization mechanisms also include the gain or loss of electrons as well as combination reactions resulting from numerous collisions between cations, anions, and neutrals in the gas phase plume. , The formation of positive ions occurs by photoionization, ion-pair formation, protonation, , and ion−molecule recombination reactions in the gas phase plume directly above the sample surface . Negative ions are formed by either electron attachment or by ion−molecule reactions …”

Analysis of anacardic acid on the surface of Pelargonium × hortorum using matrix assisted laser desorptoin ionization mass spectrometry imaging.

“…In 1988, Viswanadham and Hercules used PNA in MALDI MS experiments to investigate ion-molecule reactions of aromatic nitro compounds (Viswanadham, Hercules, Schreiber, Weller, & Giam, 1988). In the 1990's, more papers were published describing the use of PNA as a MALDI matrix Figure 10: Generation of different ion images from the same location.…”