Some mass spectrometric techniques may generate spectra whose appearance is very dependent on the experimental conditions and sample preparation. To allow the management and search of diverse product spectra with an identical precursor ion for a single chemical entity, Mass Frontier uses spectral trees that can contain nodes with several node items. The node item stands for any product or calculated spectrum of an identical precursor m/z value or m/z range (node spectra) or for a chromatogram.

Node product spectra represent spectra acquired at various collision energies and isolation widths, or using wide band activation or they can be zoom spectra, or source CID spectra, or any other spectra that enhance reproducibility in compound identification. If a node contains more than two parallel spectra, the average and composite spectra are automatically calculated. In addition to spectra, each node can contain a chromatogram.

There are several reasons for using node spectra. They can significantly contribute to correct compound identification in a tree library search, they allow the study of fragmentation processes by changing the experimental conditions, and they permit the efficient organization of product spectra. The spectral node strategy strengthens the robustness of all the mathematical processing methods and compared to simple spectra averaging does not distort the highly nonlinear peak ratio progress.

Node spectra are easily accessible from a library and can be created or edited using the graphical interface. Every tree item has its own annotation caption that can be edited by double clicking on it.

Node items can be selected by clicking the mouse on the edge of the spectral or chromatographic node item, or by browsing in the combo box displayed below the tree. All processing actions are accessible from the pop-up menu that is called up by double clicking the mouse on the node.

Spectral Tree™ is a trademark of HighChem, Ltd., Slovak Republic