3P-27 PDF
Competitive formation of M⁺• and [M+H]⁺ under ambient high electric field conditions
Ambient ionization is a useful method for in-situ analysis. Here we performed positive-ion atmospheric pressure corona discharge ionization (APCDI) experiments with benzene derivatives, and observed molecular and protonated analytes, M+. and [M+H]+, according to the structure and property of analytes. It was suggested that M+. ions were generated via an electron tunneling due to high electric field (E≈108V/m), while [M+H]+ ions were formed by proton transfer from water clusters H+(H2O)n standing in ambient ion evolution areas. The results indicated that analyte ions M+. and [M+H]+ were competitively generated dependent upon proton affinity and ionization energy of analytes.