Hey everyone! It's my favorite time of the month which means it's time for another installment of #Macademics! This week I have an exam in one of my classes so I thought it made sense to teach you all a little bit of what I'm studying. Today I'm going to teach you all about mass spectrometry - which I will now refer to as mass spect for the remainder of this post. My research group does mass spect so this is something I'm very familiar with. This is going to be very general because mass spect instruments come in various types depending on the application and what you're looking at and this would be a long post if I went through all of that. So here we go.
Mass spect is a technique that analyzes the mass-to-charge (m/z) ratio of gas phase ions. The mass spectrometer is the instrument, pictured here in a general format, and has three main parts: the ion source, mass analyzer, and detector. Each part has its own function.
First things first, since mass spect measures the mass-to-charge ratio of gaseous ions, you first need to make them first. The ionization source is how you turn a sample into gas phase ions that get introduced into the mass analyzer. There are many types of ion sources based on the type of analyte that is being detected. Some need to be ionized with the application of voltage, while others need a corona discharge. Another thing about the ionization process is that it can occur both under vacuum or even in ambient conditions.
Once the ions are made, they get sent to the mass analyzer. There are a lot of types of analyzers, just like there are ion sources, and each one serves its own purpose. For example, Time of Flight (TOF) analyzers measure how long ion take to travel from one side of a tube to reach the detector. Quadrupole mass analyzers are used to filter specific m/z values via the application of DC and AC voltages.
Finally, once the ions are made and separated based off their m/z values, they get sent to a detector. No surprise here, there are a few types of detectors too. Some act as ion counters where every ion of a given m/z = a signal. while others amplify electrons that are produced when the ions hit a surface. Most of the time no one talks about the detectors though, so I'm not going to spend a bunch of time on them here.
Overall, mass spect has a million applications. I use it to look at small molecules like illicit drugs, some use it to monitor reactions, and others study large macromolecules like proteins. Basically you can study anything with mass spect because every instrument is unique and you can tune the parts to do the analysis you want. Plus the data is pretty straightforwad to look at.
I hope you learned a little something this week. See you next month for another #Macademics installment.
- The Chemist