The new Targeted Metabolomics Unit is designed to assist in the identification and quantitative measurement of small molecules from biological samples based on mass-spectrometry coupled with chromatography and optical detection.
Mass spectrometry works by ionizing chemical compounds to generate charged molecules or molecule fragments molecule in positive or negative ionization mode and measuring their mass-to-charge ratios. The atoms or molecules in the sample can be identified by correlating known masses to the identified masses or through a characteristic fragmentation and/or isotopic pattern.
Different atmospheric pressure ionization modes can be applied (separately or in pairs) in order to get optimal ionization of the given sample:
- Electrospray ionization (ESI) uses high voltage applied to a liquid to generate charged aerosol droplets and then ions of analyte through solvent evaporation.
- Atmospheric pressure chemical ionization (APCI) occurs in a gas phase, where the corona discharges on a solvent spray and the latter ionizes the sample.
- Atmospheric pressure photoionization (APPI) arises when ultraviolet light in gas phase ionized sample directly or via solvent or dopant assistance./p>
Mass spectrometers are fronted by either gas or liquid chromatography (GC, LC). Chromatographic retention being an additional parameter in compound’s characteristics allows “purer” compounds to be introduced into MS, enhancing its identification capabilities.
- quantitative measurement of known small molecules in matrix from biological tissues;
- profiling of known compounds’ classes;
- compound’s assignment on chromatogram when a standard is not available in complex samples of biological origin
determination and quantification of small molecules from biological tissues: volatile compounds (VOCs, saturated hydrocarbons, fatty acids, alcohols, esters, etc.), small polar non-volatile compounds (amino acids, small organic acids, sugars, etc.) after volatilization (derivatization).