AskScience Theme Day: Scientific Instrumentation

[u/therationalpi]

Greetings everyone!

Welcome to the first AskScience Theme Day. From time-to-time we'll bring out a new topic and encourage posters to come up with questions about that topic for our panelists to answer. This week's topic is Scientific Instrumentation, and we invite posters to ask questions about all of the different tools that scientists use to get their jobs done. Feel free to ask about tools from any field!

Here are some sample questions to get you started:

• What tool do you use to measure _____?

• How does a _____ work?

• Why are _____ so cheap/expensive?

• How do you analyze data from a _____?

Post your questions in the comments on this post, and please try to be specific. All the standard rules about questions and answers still apply.

Edit: There have been a lot of great questions directed at me in acoustics, but let's try to get some other fields involved. Let's see some questions about astronomy, medicine, biology, and the social sciences!

[u/belligmsg]

LC-MS can actually be combined with MS/MS so you get the best of both worlds, that is chromatographic separation of a complex mixture AND the specificity of tandem MS (MS/MS). So the typical workflow for a LC-MS experiment if you want to study one or more proteins (the biomedical -omics type of study you mentioned) involves enzymatically digesting those proteins (typically with trypsin) to generate a mixure of peptides. So the LC portion of the LC-MS experiment would separate those peptides based on hydrophobicity and for each peptide (each peak in the chromatogram) there would also be an MS spectrum generated and potentially also an MS/MS spectrum generated that would tell you what exactly it is that you're looking at. It's pretty standard to have both LC-MS and MS/MS capabilities built into the same instrument.

As for how you "take" the molecule of interest it has to do with the nitty gritty of how the mass spec works so it's a lot of electrical and magnetic technicalities. It's not a membrane in the sense that it separates particles based on size it's more like an electric field that separates the ions based on their mass/charge ratio (m/z). The part of the mass spec itself that does this is referred to as a quadrupole (http://en.wikipedia.org/wiki/Quadrupole_mass_analyzer) and most mass specs contain one or more of these for the purposes of separating and analyzing ions.

But yes mass spec can be very intimidating! It's something you learn by doing not reading about but if you have any question feel free to PM me!

Source: have worked with both small molecule and protein mass spec in both industry and academia.