Name:
An introduction to mass spectrometry with Scott Summerfield
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An introduction to mass spectrometry with Scott Summerfield
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T00H04M51S
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https://cadmoreoriginalmedia.blob.core.windows.net/93931002-4240-433d-a848-134fa147a92e/EDITED AUDIO - An introduction to mass spectrometry with Sco.mp4?sv=2019-02-02&sr=c&sig=edYFWHr%2FWED4rQSEtKrXca5obu6MengbeoTF9puPDSA%3D&st=2024-11-22T23%3A34%3A25Z&se=2024-11-23T01%3A39%3A25Z&sp=r
Upload Date:
2021-12-13T00:00:00.0000000
Transcript:
Language: EN.
Segment:1 Overview of mass spectrometry in bioanalysis.
[MUSIC PLAYING]
SCOTT SUMMERFIELD: So the method I'm going to talk about today is mass spectrometry. And it's fundamentally important to bioanalysis because it allows us to get really good sensitivity and really good selectivity on very, very small quantities of sample from human subjects or animals. So mass spectrometry has essentially a few components to it. You have ionization, and the charge is really important because that allows you to move molecules around quite easily using electromagnetic fields.
SCOTT SUMMERFIELD: You have a mass detection stage, which allows you to separate the molecule of interest in its ionized form away from all the other rubbish that you don't want to monitor. And then there's also a stage of detection where you take that molecule and you convert it into an electrical current that can be read by a computer, and then turn into a value that obviously we then measure as a drug concentration, for example, in bioanalysis.
Segment:2 Ionization in mass spectrometry.
SCOTT SUMMERFIELD: So the first element is ionization. And this is where the liquid eluent comes from the HPLC column into what's called the ion source. And this is where that liquid is vaporized into small droplets. And that vaporization takes the droplets down essentially just to the naked ions, which are then transferred directly into the mass spectrometer. After the ionization process in a mass spectrometer, we then need to do the mass selection.
Segment:3 Mass selection.
SCOTT SUMMERFIELD: And, actually, generally in bioanalysis we do two phases of mass selection, one based on molecular weight, and then one based on a structural fragment ion that we generate via a process called collision-induced dissociation. An example of a mass analyzer is here. This is a quadrupole. So this is in the high vacuum. Essentially the ions move through the quadrupole.
SCOTT SUMMERFIELD: And during that movement through, electromagnetic fields essentially push low and high molecular weight ions that you're not interested in away from the one that you want. And then that molecular weight that you want to pass goes from one end of the quadrupole out to the other side. After that we do a process called collision-induced dissociation.
SCOTT SUMMERFIELD: And that's basically the founding technique of tandem mass spectrometry. And essentially that selected ion of a certain molecular weight is accelerated into a cloud of inert gas ions. Essentially what happens is a bit like a car hitting a wall. As that ion, the molecular weight that you've separated, collides with those gas molecules, some of its translational energy gets converted into kinetic energy.
SCOTT SUMMERFIELD: And essentially over time the molecule gets excited. And then it shakes itself apart and generates a fragment ion which is structurally related to the molecule that you're interested in measuring. And then after that we have a second mass selection step, which then takes the fragment that is most abundant and passes that onto the detector. So the final moment in the lifetime of a molecule in a mass spectrometer is detection.
Segment:4 Detection.
SCOTT SUMMERFIELD: And this is where the signal from the ion is turned into an electrical current, which we can then measure as a chromatogram like the one that I'm sharing over here. So essentially the ion is smashed quite hard actually into a plate, which generates electrons. And those electrons are multiplied up to an electrical signal. And the size of that signal is proportional to the concentration or the amount of drug that was on the column.
SCOTT SUMMERFIELD: Now the really big advantage of mass spectrometry is that the mass spec can select different masses and measure them sequentially. So here we have an example of where just in two and 1/2 minutes we're measuring the parent and the metabolites and the internal standards. And this is a mixture of all of them. But, obviously, the mass spec's clever enough to essentially separate them into separate channels.
SCOTT SUMMERFIELD: Now if you were doing this on a UV detector for example, you wouldn't be able to have all of those molecules co-eluting because you would only see them in terms of an absorbance. say 280 nanometers, but the mass spec sees each of those differently. And therefore you can have very fast run times, even things that co-elute with one another. And the detection of those are all discrete within the mass spec, so that then you can quantify them separately.
SCOTT SUMMERFIELD: [MUSIC PLAYING]
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