Isotope-ratio mass spectrometry (IRMS) is a specialization of mass spectrometry, in which mass spectrometric methods are used to measure the relative abundance of isotopes in a given sample. This technique has two different applications in the earth and environmental. In the first one, we provide a step-by-step beginner's guide for performing multi-elemental, intramolecular and site-specific stable isotope analysis in unlabeled polar solutes by direct infusion. The analysis. Laser-ablation resonance ionization MS, LA-RIMS, is a method in which the laser ablation of solid samples is coupled with mass-selective detection in a mass spectrometer. It can achieve isotope ratios at the ppm-level in geological, nuclear, and archaeological samples. With MS, we are looking at the mass of a molecule, or of different fragments of that molecule.
