How to Read LC-MS Chromatograms: A Brief Overview
LC-MS chromatography is a method used to separate compounds from their components. There are two main types of chromatography: capillary and column based methods.
Capillary chromatography separates compounds into their individual components while column chromatography separates them out from each other.
Capillary chromatography uses small tubes called capillaries (or “capillary columns”) which contain tiny holes or channels through which molecules pass. The bigger the molecule, the less likely it is to pass through a channel of a certain size.
This is how compounds are separated according to their sizes.
How does this work?
When a mixture of compounds is put into the column, different compounds move at different speeds, depending on their sizes. Smaller compounds move faster through the column, while bigger compounds move more slowly.
Why do we use Capillary Chromatography?
We use column chromatography because it allows us to separate mixtures of compounds very precisely. It doesn’t matter how complex the mixture is, we can always break it down into its individual components. And once separated, we can identify each component according to its physical properties (i.e. the time it takes to travel through the column).
How does Capillary LC work?
In liquid chromatography, the mixture is dissolved in a liquid (called the mobile phase). This mixture is then forced (at a high pressure) through a strip of porous material (like the plug of a bathtub). As the mixture flows through the column, the different components travel at different speeds. This is because they interact differently with the porous material. The physical and chemical properties of the various components in the mixture determine how they interact with this material.
The goal of liquid chromatography is to separate the components of a mixture. The speed that the different components move through the column is related to their physical and chemical properties.
Who invented liquid chromatography?
Sources & references used in this article:
- Minimising iTRAQ ratio compression through understanding LC‐MS elution dependence and high‐resolution HILIC fractionation (SY Ow, M Salim, J Noirel, C Evans, PC Wright – Proteomics, 2011 – Wiley Online Library)
- Metabolic profiling using combined GC–MS and LC–MS provides a systems understanding of aristolochic acid-induced nephrotoxicity in rat (Y Ni, M Su, Y Qiu, M Chen, Y Liu, A Zhao, W Jia – FEBS letters, 2007 – Elsevier)
- Toward understanding molecular heterogeneity of polysorbates by application of liquid chromatography–mass spectrometry with computer-aided data analysis (OV Borisov, JA Ji, YJ Wang, F Vega… – Analytical chemistry, 2011 – ACS Publications)
- Understanding the complexity of porous graphitic carbon (PGC) chromatography: modulation of mobile-stationary phase interactions overcomes loss of retention and … (TE Bapiro, FM Richards, DI Jodrell – Analytical chemistry, 2016 – ACS Publications)
- A proteomics approach to understanding protein ubiquitination (J Peng, D Schwartz, JE Elias, CC Thoreen… – Nature …, 2003 – nature.com)
- Understanding and manipulating the separation in hydrophilic interaction liquid chromatography (DV McCalley – Journal of chromatography A, 2017 – Elsevier)
- BatMass: a Java software platform for LC–MS data visualization in proteomics and metabolomics (DM Avtonomov, A Raskind… – Journal of proteome …, 2016 – ACS Publications)