- Quantification of targeted small molecules, both metabolites and drugs
- A variety of assays are currently available for a range of metabolites for amino acids, sugars, nucleotides, intracellular metabolites, & fatty acids.
- For most assays, stable isotopically labeled analogues are used as internal standards for precise quantification (<5% precision), and where stable isotopically labeled analogues are not available, non-natural analogues are used. The internal standards are added at the time of sample collection by the investigator to account for any sample storage, processing, or extraction losses of analytes.
- Dection limits range from <1 to 100 picomoles. Detection limits in terms of concentration are defined by the amount of sample available. E.g. an assay with a quantification limit of 10 pmol would translate to a sensitivity of measurement of 1 pmol/µL for a 10 µL sample or 1 fmol/µL for a 1 ml sample.
- Isotopomer determination of stable isotopically labeled metabolites for kinetic flux analysis
- Dr. Matthews has a 30+ year history developing the most precise measurements of stable isotopically labeled metabolites for kinetic flux analyis (e.g. see Fed. Proc. 1982 or Science 1981) and is responsible for a number of key methods used by a wide range of investigators, including precise and accurate determination of isotopomer patterns (see Anal. Chem. 2005).
- Isotopic enrichment and isotopomer pattern assays are currently available for a range of metabolites for amino acids, sugars, nucleotides, intracellular metabolites, and fatty acids & fatty acid metabolites.
- Stable isotopes that have been used for labeling, both individually and in combination, include 2H, 13C, 15N, 18O.
- Quantification limits of stable isotopic enrichment or isotopomer abundance range from <0.02 to 0.2 mole % (equivalent to 1 tracer molecule per 5,000 to 500 unlabeled metabolite molecules). Multiple isotopes or isotopomer patterns can be defined simultaneously.
- Kinetic flux analysis
- Using stable isotopically labeled data that has been measured in the facility, Dr. Matthews will provide users with the kinetic analysis scheme to calculate the metabolic flux of their analytes. Fluxes can be calculated whole organisms (e.g. humans), tissues and incubated cells. Kinetic analysis can be for specific metabolites, transfer/conversion of one metabolite into another, or metabolic pathway analysis.
- Flux analysis generally involves measurement of multiple samples taken at specific time points.
- Untargeted metabolomics measurements. These measurements take advantage of the high mass accuracy of the QTOF and metabolite databases for identification of metabolites. Relative quantification is performed using Nonlinear Progenesis QI.
