Quantitative Metabolomics

Metabolomics is the large-scale study of metabolites, the small molecules of metabolism, measured in cells, tissues and biofluids. Because metabolites sit downstream of genes and proteins, the metabolome gives the closest molecular readout of what is happening in a biological system. Most studies use liquid chromatography mass spectrometry (LC-MS) or NMR to measure hundreds to thousands of metabolites in each sample.

Untargeted metabolomics measures as many metabolites as possible for discovery, while targeted metabolomics measures a defined panel. Untargeted work finds differences between samples and generates hypotheses; targeted work confirms findings and quantifies known compounds. IROA standards and software support both approaches.

LC-MS signals shift with ion suppression, sample matrix, instrument drift and batch effects, so equal amounts can give unequal signals. Without correction, these effects can be mistaken for biology. Internal standards that behave like each metabolite are the most direct way to correct them.

Ion suppression is the loss of signal that happens when other compounds in a sample compete for ionization in the mass spectrometer source. It varies from compound to compound and from sample to sample, so it distorts comparisons. IROA corrects it compound by compound using a co-eluting carbon-13 labeled internal standard.

A stable isotope labeled standard has the same chemistry as its natural metabolite, so both elute together and experience the same suppression. Measuring the ratio between them corrects for losses that a single unlabeled measurement cannot. The IROA Internal Standard provides labeled counterparts for hundreds of metabolites at once.

IROA adds a carbon-13 labeled yeast extract to every sample, so each shared metabolite shows a natural and a labeled peak. The pair has a recognizable isotope pattern, and ClusterFinder software finds these pairs, identifies the compounds, corrects ion suppression and normalizes the data, so results stay comparable across samples, batches and instruments.

Metabolite libraries of standards are collections of authentic compounds used to record retention times and spectra on your own LC-MS method. Matching a sample feature to an authentic standard is what allows a confident identification. IROA libraries come pre-weighed in 96-well plates with plate maps and MLSDiscovery software.

Most labs start with the TruQuant workflow kit: the IROA internal standard, a long-term reference standard and ClusterFinder software. Our scientists can help you plan the workflow for your instrument and samples, so get in touch with your study details.