Mass spectrometry (MS) is an analytical technique that uses mass-to-charge (m/z) ratio to identify compounds in a sample. The method identifies a compound by determining its molecular weight and analyzing its isotopic abundance. A mass spectrometer ionizes the sample into gaseous ions and then identifies the ions by their mass-to-charge ratios and relative abundances.
Today, mass spectrometry is a well-established detection method that offers a multitude of benefits, such as selectivity, sensitivity, and multi-sample analysis.
It can be coupled to various chromatographic techniques, such as liquid chromatography, thin layer chromatography, gas chromatography, or inductively coupled plasma. Mass spectrometry is widely used across many research fields and industries, including the pharmaceutical and food industries, health clinics, clinical research labs, and forensic and environmental testing labs.
A mass spectrometer works by converting individual molecules into ions and then analyzing the relative abundance of the generated ions. In the ion chamber of a mass spectrometer, each individual molecule is ionized to form a molecular ion, having one electron less than the parent molecule. Molecular ions, or ‘radical cations’, then undergo fragmentation into ions which, in turn, are further fragmented, and so on. From one complex sample, a mass spectrometer generates many ions. The ions are then accelerated in an electromagnetic field and separated based on their mass-to-charge (m/z) ratios. The instrument’s detector records the ions in proportion to their relative abundance and generates a mass spectrum of the molecule.
Due to the sensitivity of mass spectrometry, it is widely used to measure very low molecular weights at extremely low concentrations, below nanograms per milliliter (ng/mL). The ability to couple mass spectrometry to other separation techniques such as capillary electrophoresis, GC, and HPLC makes it a versatile analytical tool for the simultaneous separation and identification of analytes.
Typical applications of mass spectrometry include: