Matrix-Free Laser Desorption/Ionization of Lipid Analytes on Metal Oxide Surfaces

摘要

Nickel oxide with the exposed <100> surface facet reproducibly produces signals for a variety of analytes which are free from matrix interference. Chemisorption through carbonyl oxygen results in an acidic alpha-proton which is likely involved in the ionization process. This was confirmed with DRIFTS and isotope labeling. The NiO system has been succesfully used for analysis of complex lipid mixtures such as vegetable oil shortening and the addition of a proton source pretreatment such as methy acetate has further expanded the application of the method to polypeptides and organo-phosphate esters. NiO laser ionization is a rapid and robust ionization technique for analyzing compounds relevant to biofuels, foods, biomedicine, and national security.