Atmospheric pressure laser desorption/ionization of plant metabolites and plant tissue using colloidal graphite.

Colloidal graphite is a promising matrix for atmospheric pressure laser desorption/ionization mass spectrometry. Intact [M+H](+) and [M-H](-) ions are readily produced from a wide range of small molecule plant metabolites, particularly anthocyanins, fatty acids, lipids, glycerides, and ceramides. Compared with a more traditional organic acid matrix, colloidal graphite provides more efficient ionization for small hydrophobic molecules and has a much cleaner background spectrum, especially in negative ion mode. Some important metabolites, e.g., fatty acids and glycosylated flavonoids, can be observed from Arabidopsis thaliana leaf and flower petal tissues in situ.