RESUMEN
A novel mass spectrometric imaging method is developed to reduce the data acquisition time and provide rich chemical information using a hybrid linear ion trap-orbitrap mass spectrometer. In this method, the linear ion trap and orbitrap are used in tandem to reduce the acquisition time by incorporating multiple linear ion trap scans during an orbitrap scan utilizing a spiral raster step plate movement. The data acquisition time was decreased by 43-49% in the current experiment compared to that of orbitrap-only scans; however, 75% or more time could be saved for higher mass resolution and with a higher repetition rate laser. Using this approach, a high spatial resolution of 10 µm was maintained at ion trap imaging, while orbitrap spectra were acquired at a lower spatial resolution, 20-40 µm, all with far less data acquisition time. Furthermore, various MS imaging methods were developed by interspersing MS/MS and MS(n) ion trap scans during orbitrap scans to provide more analytical information on the sample. This method was applied to differentiate and localize structural isomers of several flavonol glycosides from an Arabidopsis flower petal in which MS/MS, MS(n), ion trap, and orbitrap images were all acquired in a single data acquisition.
Asunto(s)
Espectrometría de Masas/métodos , Imagen Molecular/métodos , Arabidopsis/metabolismo , Flavonoles/química , Flavonoles/metabolismo , Flores/metabolismo , Análisis de Fourier , Glicosilación , Isomerismo , Imagen Molecular/instrumentación , Espectrometría de Masas en Tándem , Factores de TiempoRESUMEN
Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations at the cellular level.
Asunto(s)
Astrocitos/química , Colesterol/química , Plata/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Animales , Astrocitos/metabolismo , Membrana Celular/química , Membrana Celular/metabolismo , Células Cultivadas , Colesterol/metabolismo , Coloides , Hipocampo/citología , Ratas , Espectrometría de FluorescenciaRESUMEN
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.