I have, once again, found myself at the helm of a DIY lab, this one with a chemical wetlab focus. I’m sure this will provide lots of material in the future; right now, I want to share a protip I came up with the other night. I have been using soda can alcohol stoves for heat, but this isn’t always appropriate. You can’t heat flammable mixtures, and they leave soot on my glassware. But I don’t have a hotplate yet! What’s a gutterpunk labnerd to do?
Don’t forget the boiling chips!
It’s won’t spin a stir bar, but a clothes iron will do fine as a hotplate! You can see that I’ve secured this one to the lab bench with wood and a clamp for extra stability.
There is a more philosophically focussed companion article over at ArkFab.
At long last, second generation DIY spectro has arrived!
The spectrophotometer. Yes, that is an invisibility cloak. You can't see the stuff that's under it can you? Then that stuff is invisible!
If you recall, when last we left our humble spectrophotometer, it was a shambling mess of stone-age technology. Now, its a shambling mess of information-age technology!
Let’s take a closer look… Continue reading
A Detective Story
About to run the Final Qualifying Round for some second generation DIY Spectro, I placed the first blank into the cuvette holder, and pressed start (or rather ran python tryna.py; I’m tryna measure a spectrum, gosh!). The machine hummed into action, now that the motor control wire was plugged into slot 9, which the computer was communicating with rather than slot 2, which the computer was not.
A few minutes later I got the results: Nothing. The machine was not seeing any light. At all.
See, normally when I scan a blank sample, the detector (which has different sensitivities at different colors) shows a characteristic hill shape:
- Some typical blank sample runs. Horizontal axis is motor position in degrees (0-180) and vertical axis is detector response. Black is the mean of the time series coming from the detector at a given motor position (1 sec data per degree); green is the standard deviation of the time series, and red denotes the maxima/minima. Time series were preprocessed to remove annoying serial communications glitches.
But when I ran this blank: Continue reading