Analysis of hydroxy-containing seed oils using atmospheric pressure chemical ionization mass spectrometry

Atmospheric pressure chemical ionization mass spectrometry (APCI-MS) coupled to reversed-phase high performance liquid chromatography (RP-HPLC) was used for direct analysis of intact triacylglycerols (TAGs) from hydroxy-containing plant oils. Castor bean oil, Lesquerella fendleri and Lesquerella gordonii oils were separated into tri-hydroxy, di-hydroxy, mono-hydroxy, and non-hydroxy TAGs using the RP-HPLC method. The APCI-MS ionization source produced fragments representing loss of zero (protonated molecular ion), one, two, and three hydroxy groups. The primary fragments (base peaks) in the mass spectra resulted from loss of all hydroxy groups from the TAGs. Using the acetonitrile/methylene chloride solvent system, diagnostically important acetonitrile adducts were formed which allowed identification of the molecular weights of the hydroxy TAGs as well as confirmation of the number of hydroxy groups contained therein. A series of four adducts was formed: [M+23](+), [M+39](+), [M+54](+), and [M+59](+).