Late Night

Post written by Charlie:

So it seems that my previous blog was a bit premature. At the time I was writing it I was under the impression that my night was over a little early. As you can infer from the first sentence of this entry, it wasn't. Shortly after I wrote it, the call came in that we had netted several krill and that we were to right then and there cut off their eyes. There were 38 krill to do this to and while I had a little practice under my belt, it is still a delicate procedure and caution must be taken. I did half of the batch while my lab-mate did the other half. Still, with about 20 krill, the job took a little over an hour.

With those krill eyes, we were able to do quite a bit of work tonight. The eyes were dunked in a little bit of solvent and blasted with sound waves in a machine called a sonicator. It basically uses sound to beat up whatever sample you put into it, in our case it bashed around those eyes and helped get some of the lipids out of them. The compound we were looking for is, as you probably know from the last few blogs, lipofuscin. After we sonicated them, we did a few more steps to prepare the biochemical compounds for analyzing in our HPLC, or High Performance Liquid Chromatography. This machine, in a very simple explanation, detects and quantifies compounds in the sample that you feed into it, so with our lipid sample that we fed into the HPLC, the machine will tell us what is in it and give us an estimate about how much of it there is. It's rather complicated and I'm afraid I still don't know everything about it yet, so I'm sorry that I can't give you a super in-depth explanation about it, not that I would anyway.** I wouldn't want to bore you with a bunch of technical facts, so this simple example of the functions of the HPLC will have to suffice. Anyway, after working on all that krill stuff, which took just about the entire evening, we decided to eat some breakfast and call it a night. We're all really tired so I'm headed off to bed. Keep in touch. Morgan out.

**The webmaster will bore you with the details of HPLC, so for those that are interested, read on:

In general, chromatography refers to techniques that are used to separate complex mixtures into individual chemical compounds for purification or measurement. Here's a handy example: let's say you want to know how much cholesterol is in one Arctic krill. You would take the krill and extract its fat. But now you've got a huge mix of all its lipids, including fatty acids and alcohols, waxes, and sterols. Chromatography provides a way to separate these lipids so you can measure the amount of each individual lipid, including cholesterol.

There are many different types of chromatography that can be used, depending on the samples you are interested in and what chemicals you want to isolate or measure. Some common types are gas, liquid, thin-layer, ion exchange, etc. No matter the type, all chromatography has a stationary phase (a fixed substance that your sample moves through so that individual chemicals can be resolved) and a mobile phase (what you use to move your sample through the stationary phase).

HPLC, or high performance liquid chromatography, uses a liquid as the mobile phase, typically organic solvents or water. The stationary phase is usually a column packed with a type of solid material (often silica or aluminum oxide particles, or chains of carbon atoms bonded together). You inject your sample (a mix of chemicals) into the column. A pump is used to push the liquid mobile phase through the column, sweeping your sample along with it. As your sample moves through the column, some chemicals in the mix react with the column particles and stick or only move very slowly. Other compounds don't react with the stationary phase at all, and move right through. A detector at the outlet of the column allows you to measure the individual compounds exiting the column. You can adjust both the mobile phase and the stationary phase to optimize separation of your compound of interest. I hope this helps explain chromatography a little bit. If you have questions, feel free to post a comment and we will try our best to answer it.