Studies on 1-alkylamine adduct formation in electrospray ionization mass spectrometry for quantitative analysis

J Pharm Biomed Anal. 2008 Aug 5;47(4-5):962-6. doi: 10.1016/j.jpba.2008.03.025. Epub 2008 Mar 30.

Abstract

We investigated the formation of 1-alkylamine adduct ions using 1,2-, 1,3-, and 1,4-cyclohexanediol (CHD) as model compounds and the relationships of the peak intensity between the protonated molecules ([M+H]+), sodium adduct ions ([M+Na]+), and 1-alkylamine adduct ions ([M+A+H]+) of 16 model compounds using electrospray ionization mass spectrometry. When 1-octylamine was added to 1,2-, 1,3-, and 1,4-CHD solutions, the peak intensity of the 1-octylamine adduct ions ([M+Oct+H]+) was higher than those of [M+H]+ and [M+Na]+. The highest peak intensity of [M+Oct+H]+ was observed in 1,2-CHD, followed by 1,3-CHD and 1,4-CHD and this order was the same as that of [M+Na]+ for CHDs in the solution without 1-octylamine. These results suggest that the mechanism of formation of [M+Oct+H]+ is similar to that of [M+Na]+ and that adduct formation seems to occur between 1-octylamine and two oxygen atoms in CHD in a similar manner to [M+Na]+. Based on these results, 16 model compounds including CHDs were investigated with respect to the relationship between [M+Na]+ and [M+A+H]+. A positive correlation was observed between the peak intensities of [M+Na]+ and [M+A+H]+, supporting that the formation mechanism of [M+A+H]+ is potentially similar to the [M+Na]+ formation mechanism. These data indicate that a sensitivity enhanced quantitative analysis using [M+A+H]+ could be a feasible approach for compounds generating [M+Na]+.

MeSH terms

  • Acetic Acid / chemistry
  • Amines / analysis*
  • Amines / chemistry
  • Cyclohexanols / chemistry*
  • Feasibility Studies
  • Ions / chemistry
  • Methanol / chemistry
  • Models, Molecular
  • Molecular Structure
  • Sensitivity and Specificity
  • Sodium / chemistry
  • Solutions / chemistry
  • Spectrometry, Mass, Electrospray Ionization / methods*
  • Stereoisomerism
  • Water / chemistry

Substances

  • Amines
  • Cyclohexanols
  • Ions
  • Solutions
  • Water
  • Sodium
  • Acetic Acid
  • octylamine
  • Methanol