Principles of Pattern Recognition

Although elution time from a LC separation provides valuable information for a particular species, definitive identification of the lipid species has to be performed based on its product-ion mass spectrum. For those researchers who are using LC-MS for identification and quantification of lipid species, familiar with the fragmentation patterns of lipid classes, therefore deriving the product-ion mass spectra of individual lipid species, is very important although a few databases and/or libraries (see Chapter 5) can be used to aid the identification. Resolving complex biological lipids into a 

For those who would like to employ shotgun lipidomics (particularly MDMS-SL) for identification and quantification of individual species of a class, familiar with the fragmentation patterns of individual lipid classes, could enable them to design MS/MS scans for building-block analysis in the PIS, NLS, or both modes to selectively identify individual molecular species of a lipid class of interest. 

The following are a few examples to demonstrate how an elucidated fragmentation pattern can be used for identification of individual species of a lipid class present in biological samples by MDMS-SL. These examples well represent different lipid classes (e.g glycerophospholipids, sphingolipid, and glycerolipids), different mass levels (from low abundance to abundance), different polarities (Ifom polar to non-polar), etc. 

---

The concept of transferability and a detailed understanding of these amide modes provides the basis for quantitative estimation of secondary structure for unknown proteins and polypeptides. The quantitative methods currently used to analyze vibrational spectra of proteins can be classified into two categories (1) methods based on decomposition of band contours into underlying components characterized by distinct frequencies, and (2) methods based on principles of pattern recognition. 

---