Beaker is running an old UV spec, it has a flow through cuvette. such a beast would also solve the running blind problem.
I’m not sure how much he paid for it. not a fortune. He’s just doing this for fun/personal meds.
you’re right. no reason to expect an anti-oxidant to be required in much more than catalytic amounts. I’m high and was working from first principles. didn’t get as far as consulting [currently inaccessible] stored data on anti-oxidants.
hmmm, it’s either little, or there is f.all of it.
Attack strategy sounds appropriate. I’ll gladly share data once I have my hands on a WFE.
I should also clarify that, fats & waxes, even if it might be AN answer (certainly not THE answer) to slowing down oxidation, it is certainly not an acceptable one:
unwinterized distillate hasn’t been acceptable since 2013/2014 at least
there are way too many examples of distillate with fats and waxes removed, that don’t have oxidation issues
ideally you want a device that reads out from the eluate drip tube, stores & displays that data (chart recorder is old school) AND automagically dispenses into measured aliquots (fractions, in tubes/vials/mason jars… .). you can get by with out the automagic fraction collection (they’re usually shit anyway) if you’re not planning on doing it on a regular basis. or once you learn where your magic elutes.
I’m sure @Beaker will respond with a model number if we keep paging
I would assume summit’s detector looked much like the $500 ebay unit linked above. perhaps without the fraction collector.
I seen folks buildingcell sorters using $5 UV emitting diodes and cheap photo-detectors to detect their target.
ideally you want a diode array, with LED’s emitting at a variety of wavelengths.
A UV/Vis spec with a flow through cuvette would give you access to a lot more information. it would take up more room on your lab bench, but should come relatively cheap used.
I searched for UV/Vis Spectrophotometer flow through. pulls up some other candidates. none qualify as cheap.
I imagine an old Gilson or Beckman UV detector would get you most of the way. I’m pretty sure that’s what I’ve seen paired with a fraction detector and a chart recorder on older HPLC’s
At a guess I’d say the gilson would be easier to interface with.
My unit is a Hach DRU 4000 with a pour through module. It is 15+ years old.
The unit uses two bulbs. A tungsten bulb for VIS and Dueterium bulb for UV. The bulbs have a shelf life and it is taken up in warm up and runnning both. So turning on a bulb from cold puts about as much wear on the bulb as if you left it on for 8 hours or more. The unit is fairly slow at producing a spectrum scan but obviously you are wishing a single wavelength scan. The pour through module makes this pretty simple because you do not have to remove cuvettes.
I would not recommend a used Hach unit. The one I have works for the data but the old ones are notoriously finicky. There is a multitude of seperate circuit boards inside as was the design style back then . Power supply boards and the interconnects between boards are with plastic electrical clips on the wire ends that plug the boards together. I worked a career as a control systems design engineer and saw this over and over because I had to design with this kind of component. Over time those connections tend to oxidize and resistance builds. The problem with an oxidized connection is that it is not like either a broken wire or a short circuit and so a voltmeter is very tricky to use to track down problems. Voltages must be read across the connection which most electricians will not understand to do to track this stuff down.
All sorts of glitches creep with oxidized connections and components that will drive you nuts. Error codes will come and go and you have to know where to bang the cabinet and why to make some things boot up lolz. I am certain without an extensive electronics and motion control machine design knowledge a typical user would have returned the unit or trashed it immediately. It has value to me because I have only used it to take single measurements here and there and it is hobby. When I hit the lottery again, or at least if I make it through my disability review, I am looking at a new uv/vis unit.
The new models are surface mount circuitry and generally like all electronics are much more reliable. Plus a unit with a halogen bulb likely never needs the bulb replaced unlike standard tungsten and Dueterium bulbs. Old units like mine needed several minutes to warm the bulb up to temp. Halogen bulbs provide both UV and VIS light and need no warm up. If I sacrifice a small amount of resolution and select a model that scans the entire spectrum at the same time then every scan will have the entire spectrum stored in the same time it took me to scan just one wavelength on my old machine. This type of unit is called a photo detector array unit and they sacrifice a bit of resolution for the incredible option of full spectrum scanning instantaneously.
I don’t disagree with your concerns about such ancient technology. replacement bulbs are pretty expensive from what I recall. finding a manual & then chasing down replacement bulb options before jumping would not be a bad idea.
If you wanted to purchase new, you would be looking in the $5k range. for a fairly simple unit.
What about blow down evaporation? Use a length of copper tubing coiled inside a heating mantle. Have a bottle of nitrogen in a flow meter hooked to the coil, the other end should have a blunt needle or something to direct the hot gas into the top of the tube. If your fancy you can make a mantafold to do all your samples at once.
Might sound like something super basic. But I have had luck with loading the flask with C-Bleach and adding about a teaspoon of citric acid. Very limited to no oxidation over time.
