Mass Spectrophotometer

It’s Sunday. I had planned on getting the next part of my shed done (laying the concrete and bricks for the foundation), but forgot that shops don’t open Sundays. Damn.

The next time I’ll be free to work on this will be Wednesday, so I’m stuck here with nothing much to do but imagine.

I was trying to figure out which tools I need to build first once the lab is completed.

The end goal is to produce my own medicines/drugs, so I will need to develop a protein synthesis machine. I said yesterday that I thought it would be possible to do with home-built equipment. After reading up on it further, I am certain of that now.

But, there is no point starting off with that, yet. Even if I built a machine which could build proteins (using “solid state protein synthesis” – very simplified explanation here), I would have no way of being sure that it worked.

So, I need to build a measurement device first that can identify proteins.

The most common method used in a lab is by using a mass spectrometer. Those are quite expensive, even if you build them yourself.


Mass spectrophotometers, though, are cheap to build. The idea is simple – dissolve your sample in a solution, shine light of various colours through the solution, and measure the strength of the light that gets through the sample by using a light-dependent resistor. Here’s a video showing one in action. The diffraction grate is rotated a little at a time to change the frequency of light being inspected, and the voltage change is shown on screen.

The diffraction grate, by the way, is made from a piece of CD or DVD! If you shine light onto a DVD and look at the reflection, the light is broken apart into its various colours. This happens because of quantum mechanics. I thought I understood the mechanism (as described in Brian Cox’s book “The Quantum Universe”), but Wikipedia’s description is confusing.

Even while I’m building the protein synthesis machine, this will still be useful – I can use it to analyse the content of my garden’s soil to figure out the best crops to grow in it 😉

So, I now have a small shopping list of things to buy to build this spectrophotometer.

In fact, I might already have all the ingredients! I think I’m missing a light dependent resistor, but might not be…

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