It's been a while since my last post! I was on vacation with my family for a week, and lab has been keeping my busy since I got back. This is my 9th consecutive day in lab now, and it's only Tuesday. I think. Turns out that, even though I only worked half days on Saturday and Sunday, not having any full days off makes it quite easy to lose track of time.
When I'm in lab for too long, I start thinking about weird stuff. Let me start by explaining a little about what I actually do in lab. I more or less do "metabolomics" which means I measure metabolites. Metabolites are small molecules that pretty much do everything in your body. They include things like sugars, amino acids, vitamins, hormones, neurotransmitters, etc. There are literally thousands of them.
I measure these molecules with mass spectrometry. You may be familiar with the term from a chemistry class or your favorite forensic-type tv show. The mass spec ionizes everything in your sample, and separates things based on their mass/charge ratio (m/z). How the ions are separated depends entirely on the type of mass spec you're using, and it's not really relevant. The end result is a spectrum which tells you how much stuff there is in your sample at each m/z. Oh but wait, remember how there's thousands of chemicals floating around in your body? Turns out that the spectrum is too complex to get any useful information out of. Especially since lots of the metabolites can have the same m/z.
How do we solve this? By adding in an additional separation step. In this case, liquid chromatography. Have you ever taken a coffee filter, dotted some markers on it, and then stuck it in some water? As the water is drawn up the filter (capillary action), the colors in the marker separate and smear out, like so. That happens because the different chemicals that make up the marker inks have different levels of attraction to the water and the coffee filter. Chemicals that are more attracted to the paper don't want to move because they're happy on the paper, so they don't move very far. Chemicals that are more attracted to the water will just hang out with the water and they travel up the paper faster.
Take that same principle, but make it much more expensive, and you get liquid chromatography. You have a column packed with your stationary phase (i.e. the paper) and you flow your sample through with the mobile phase (i.e. the water). Compounds that is more attracted to the mobile phase travel through the column faster than the compounds which are more attracted to the stationary phase. After they finish going through the column, they enter the mass spec. So now you get a mass spectrum at many many time points, and each spectrum will have fewer compounds on it so it's easier to figure out what you have in your sample.
But wait! Given how many metabolites there are, it's still pretty likely that you can have multiple compounds with the same m/z that will elute from the column at the same time. How do we deal with this? After all, if I say that this is dopamine I'm measuring, it better actually be dopamine!
Answer here is to smash stuff up. Again, there are a few different ways to do this, but the point is that molecules will break up in specific ways, giving new ions with new m/z's. So if this thing that you think is dopamine elutes at the same time as dopamine, has the same initial mass as dopamine, and the same mass after smashing it up as dopamine, well now you can be pretty certain it actually is dopamine.
Ok, so a lot of the chemicals I specifically measure are neurotransmitters. People in my lab do work with cerebrospinal fluid, but most of my work has been with blood plasma or more recently, smashed up fruit flies. But the same methods I use can be applied to urine and saliva as well. Sometimes I get bored and think, hmm I could just spit in a tube and see what's actually going on in my saliva. If I did this every day, would I see a decrease in serotonin on the days when I'm sad? What if I don't get "runner's high" because I have low levels of epinephine (adrenaline)? I don't actually do this ever because I think there's some ethical issues somewhere in it. But it's crossed my mind more times than I can count.
Or when I'm making up solutions of these compounds. Would ingesting ATP give me more energy? Is the sucrose we have really identical to table sugar? Would amines taste like fish just because they smell fishy? What would HPLC grade (super pure) water taste like?
Maybe I need to get a hobby to get my mind off science all the time. I had a dream once that a labmate attacked me with histamine so I'd get allergy symptoms. That is not normal. But alas, I have more smashed up fruit flies to attend to.
No comments:
Post a Comment