Elements Ennoble Bio-Mass Spectrometry

In the early years of the 20th century, mass spectrometry (MS) entered the stage of analytical methods with a spectacular discovery – a proof of the isotopic nature of elements. Decades passed until the challenging problem of intact and sensitive detection of organic molecules and of biopolymers by MS was solved in the mid 1980s. For the final steps in this development, namely the introduction and application of suitable mass spectrometric ionisation techniques, two Nobel Prices were awarded last year.

Although less brightly illuminated, element mass spectrometry has also seen revolutionary innovations in the last decades. The introduction of inductively coupled plasma (ICP) ionisation followed by the development of high resolution ICP-MS instruments and quadrupole ICP-MS instruments with collision/reaction cells has resulted in nearly every element of the periodic system becoming accessible. Among these are important elements of the biosphere, such as selenium, phosphorus, sulfur, chlorine, bromine, or iodine. This has led to innovative studies in the life sciences, where ICP-MS and electrospray MS have been jointly applied to a single analyte for its characterization on the molecular and element level. So far such studies include metabolism of halogenated drugs, structural analyses of selenoproteins, studies of protein phosphorylation, and quantification of proteins.

Analytical departments in the pharmaceutical industry early recognized the potential of the combined approach of element and molecular mass spectrometry coupled to chromatographic methods and appear to take the lead in this field – as for other  advanced MS technologies. The challenges of drug development and quality control have resulted in the historical separation of inorganic and organic MS being gradually replaced by a more interdisciplinary approach. In this way, information on molecular weight, element composition, structure, and  quantity of an individual analyte can be assessed to greater depth and with more confidence than is possible with molecular MS alone.