ESI-Orbitrap IRMS: A Revolutionary Tool with Pros and Cons

Electrospray ionization (ESI) with Orbitrap technology gives access to the isotopic anatomy of intact organic and inorganic molecules. Key aspects are soft ionization by ESI, target separation by quadrupole and high-resolution accurate mass (HRAM) spectrometry in the Orbitrap. For the first time we now can read natures fingerprints compounds. Orbitrap IRMS delivers isotope ratios of singly substituted isotopologs, clumped isotopes and position specific isotope analysis.

As many fields of application have started to do research with Orbitrap IRMS a discussion of its pros and cons is required to give guidance in the development of new applications. Some of the key aspects discussed in this presentation are,

-       Analysis of intact molecules from liquid samples

-       Simultaneous access to multiple isotopologs carrying ¹³C,¹⁵N,¹⁸O, ³⁴S, and ²H

-       High sensitivity with concentrations down to 1 pmol/µL and sample consumptions of
< 1 nmol per compound

-       High specificity by HRAM removing contaminants and interferences

-       Equal ESI conditions for samples and references

-       Selection of target compounds by HPLC

-       Peak broadening to acquire data for > 5 min to reach < 1‰ precision

-       2-point referencing and new reference compounds

We also will give insight to Orbitrap IRMS technology, sample introduction techniques, data evaluation and will highlight latest applications on oxyanions, amino acids and first steps in the deconvolution of metabolic pathways.