Merck
  • Inicio
  • Resultados de la búsqueda
  • The formation of [M-H]+ ions in N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione derivatives during atmospheric pressure photoionization mass spectrometry.

The formation of [M-H]+ ions in N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione derivatives during atmospheric pressure photoionization mass spectrometry.

Rapid communications in mass spectrometry : RCM (2014-10-11)
Salim Sioud, Najeh Kharbatia, Maan H Amad, Zhiyong Zhu, Clement Cabanetos, Alain Lesimple, Pierre Beaujuge
RESUMEN

The formation of ions during atmospheric pressure photoionization (APPI) mass spectrometry in the positive mode usually provides radical cations and/or protonated species. Intriguingly, during the analysis of some N-alkyl-substituted thieno[3,4-c]pyrrole-4,6-dione (TPD) derivatives synthesized in our laboratory, unusual [M-H](+) ion peaks were observed. In this work we investigate the formation of [M-H](+) ions observed under APPI conditions. Multiple experimental parameters, including the type of ionization source, the composition of the solvent, the type of dopant, the infusion flow rate, and the length of the alkyl side chain were investigated to determine their effects on the formation of [M-H](+) ions. In addition, a comparison study of the gas-phase tandem mass spectrometric (MS/MS) fragmentation of [M + H](+) vs [M-H](+) ions and computational approaches were used. [M-H](+) ions were observed under APPI conditions. The type of dopant and the length of the alkyl chain affected the formation of these ions. MS/MS fragmentation of [M-H](+) and [M + H](+) ions exhibited completely different patterns. Theoretical calculations revealed that the loss of hydrogen molecules from the [M + H](+) ions is the most favourable condition under which to form [M-H](+) ions. [M-H](+) ions were detected in all the TPD derivatives studied here under the special experimental conditions during APPI, using a halogenated benzene dopant, and TPD containing substituted N-alkyl side chains with a minimum of four carbon atoms. Density functional theory calculations showed that for [M-H](+) ions to be formed under these conditions, the loss of hydrogen molecules from the [M + H](+)  ions is proposed to be necessary.

MATERIALES
Referencia del producto
Marca
Descripción del producto

Sigma-Aldrich
Acetonitrile solution, contains 10.0% acetone, 40.0% 2-propanol, 0.05% formic acid
Sigma-Aldrich
Acetonitrile solution, contains 0.05 % (w/v) ammonium formate, 0.1 % (v/v) formic acid, 5 % (v/v) water, suitable for HPLC
Sigma-Aldrich
Methanol, anhydrous, 99.8%
Sigma-Aldrich
Bromobenzene, ReagentPlus®, 99%
Sigma-Aldrich
Chlorobenzene, anhydrous, 99.8%
Sigma-Aldrich
Acetonitrile solution, contains 0.05 % (v/v) trifluoroacetic acid
Sigma-Aldrich
Acetonitrile solution, contains 0.1 % (v/v) trifluoroacetic acid, suitable for HPLC
Supelco
Methanol, analytical standard
Sigma-Aldrich
Bromobenzene, ≥99.5% (GC)
Sigma-Aldrich
Acetonitrile solution, contains 0.1 % (v/v) formic acid, suitable for HPLC
Supelco
Chlorobenzene, analytical standard
Sigma-Aldrich
Methanol, suitable for HPLC, gradient grade, ≥99.9%
Sigma-Aldrich
Methanol, suitable for HPLC, ≥99.9%
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
Sigma-Aldrich
Methanol, Laboratory Reagent, ≥99.6%
Sigma-Aldrich
Methanol, suitable for HPLC, gradient grade, suitable as ACS-grade LC reagent, ≥99.9%
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
Sigma-Aldrich
Methanol, Absolute - Acetone free
Sigma-Aldrich
Methanol, ACS spectrophotometric grade, ≥99.9%
Sigma-Aldrich
Chlorobenzene, ReagentPlus®, 99%
Sigma-Aldrich
Chlorobenzene, ACS reagent, ≥99.5%
Sigma-Aldrich
Chlorobenzene, puriss. p.a., ACS reagent, ≥99.5% (GC)
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
Sigma-Aldrich
Chlorobenzene, suitable for HPLC, 99.9%
Sigma-Aldrich
Methanol, HPLC Plus, ≥99.9%
Sigma-Aldrich
Methanol, puriss. p.a., ACS reagent, reag. ISO, reag. Ph. Eur., ≥99.8% (GC)
Sigma-Aldrich
Methanol, puriss., meets analytical specification of Ph Eur, ≥99.7% (GC)
Sigma-Aldrich
Acetonitrile solution, contains 0.035 % (v/v) trifluoroacetic acid, suitable for HPLC
Sigma-Aldrich
Methanol, BioReagent, ≥99.93%
Supelco
Methanol, Pharmaceutical Secondary Standard; Certified Reference Material