Reversed-phase HPLC/MS analysis of fatty acid 9-anthrylmethyl ester derivatives

Abstract

We have investigated reversed-phase high-performance liquid chromatography (HPLC) in conjunction with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of the 9-anthrylmethyl ester derivatives of long-chain fatty acids. The positive ESI-MS gave a prominent [M + Na]+ (base peak) ion and a weak [M - RCOO]+ (m/z 191) ion, while the APCI-MS showed prominent [RCOO] - and [M-RCOO]+ (m/z 191) ions in negative and positive ion modes, respectively. By using these ions obtained by ESI-MS and APCI-MS, saturated and unsaturated fatty acids were identified satisfactorily. The detection limit (S/N = 5) by selected ion monitoring (SIM) in negative ESI was 0.1 ng for a mixture of the fatty acid derivatives. The fatty acid compositions (peak area%) of a mink whale oil obtained by positive ESI-MS were in good agreement with those obtained by reversed-phase HPLC with fluorescence detection. The present HPLC/MS method for fatty acid anthrylmethyl esters can be utilized for the identification and quantification of complex fatty acid mixtures in biological samples.