Food analysis APCI interface

The detection and identification of phenolic compounds, including phenolic acids, have also been simph-fied using mass spectrometry (MS) techniques on-hne, coupled to the HPLC equipment. The electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) interfaces dominate the analysis of phenohcs in herbs, fmits, vegetables, peels, seeds, and other plants. In some cases, HPLC, with different sensitivity detectors (UV, electrochemical, fluorescence), and HPLC-MS are simultaneously used for the identification and determination of phenolic acids in natural plants and related food products.In some papers, other spectroscopic instmmental techniques (IR, H NMR, and C NMR) have also been apphed for the identification of isolated phenolic compounds. 

Lately, LC—MS analysis of carotenoids and retinoids has been reported for food matrices such as fish eggs [104] and infant formula [105,106]. Atmospheric pressure chemical ionization (APCI) is the method of choice for their detection in the positive ion mode Retinol gives an intense dehydrated pseudomolecular ion, [MH—H20], at zzz/z 269 retinyl esters are fragmented in the ion source producing [MH—fatty acid—H20] ions (i.e., retinol dehydrated at zzz/z 269) carotenoids generate several ions such as [M + H]" ", [M]" ", and [M—H]" ". The ESI interface is better for the ionization of xanthophylls when semiaqueous mobile phases are used for their separation. 

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