Debating Resolution and Mass Accuracy

A mass spectrometer's resolution and mass accuracy are the primary considerations for determining whether an instrument suits its intended purpose. Unlike UV and other chromatographic detectors that provide inferential data, mass spectrometers have traditionally provided chromatographers with qualitative information. Now that these instruments are becoming fairly commonplace in liquid chromatography (LC) systems, chromatographers expect them to provide not only mass data but also to possess all the usual performance attributes of traditional detectors, such as dynamic range and sensitivity. colleague and a well-recognized practitioner in proteomics work, underscores the confusion most practitioners face when they attempt to evaluate and employ a mass spectrometer's capabilities. He describes their almost daily frustration with the failure of well-intended attempts to replace good analytical practice with new technology. Martin's succinct argument is: " A well-prepared sample, a well-defined analytical goal, the appropriate use of accurate mass, reproducible retention times and good instrument control generates unassailable data. " To this he adds: " Make it run in triplicate, and [you] get real data from which to draw conclusions. " But there's an opposing argument, one brought by those who embrace the ever-increasing technological sophistication of these instruments and the software that operates them. It propounds the " one-time " phenomenon, where an operator requires only a single run to obtain a correct result. This argument champions an easy alternative to the daunting prospect of amassing enormous well-conceived data files, hinting seductively at something novel and more intriguing than the grunt work entailed in complex tasks such as characterizing facile changes in metabolic–host interactions in systems biology. This month we take a quick look at what has become a confusing debate for many: When considering accurate mass and greater resolution, which mass spectrometer provides the information needed at the best purchase price and with the most accessible operational prospects? An industry report summarizing a number of interviews states: It often seems that end-users are confused as to which types of LC–MS [instruments] are best for them. While in some cases, the performance requirements are so stringent that the choice is simple, more often than not, a potential customer must attempt to weigh the trade-offs of a particular type of LC–MS [instrument] for the application. 1 When Klaus Biemann, renowned scientist and professor of chemistry at Massachusetts Institute of Technology (Cambridge, Massachusetts, USA), submitted in 1962 what would become a pivotal manuscript to the Journal of the …