Well, I don’t think I have ever seen that on my TLC. Goddamn spots ran as loops. Also, I have no starting material left. And I have blue glowie fluorescence! WOOT! Easiest macrocycle I’ve ever made.
(My normal lab camera, a Nikon D80, is resting at home. If you’re going to get a camera for lab and blog use, you should invest in a decent digital SLR. As you can see, that picture is bullshit.
Up next… Sigma Aldrich, I fucking hate you.
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That’s one big fucking macrocycle.
Mine is bigger than yours.
Whilst I am a useless chromatographer I have seen that before. I think it happens when the solvent you spot your compound on the plate with moves the compound up/around the silica very fast, so each time you spot your compound moves out to the edge of the little blob of solvent.
I think your compound is saying to you that dissolving your stuff in straight methanol (or some other ridiculously polar solvent) and not drying the spots properly between repeated spotting can make you look like tits
this. seems to happen more often when you have to re-spot a lot–i’ve seen it with EtOAc too
What do you mean by respot? For the last 8 years I’ve done the same thing – 3 spots off the spotter and I have never seen loops.
Toluene, actually – no methanol to be found.
“Toluene, actually – no methanol to be found. ”
so? aromatic solvents can be very “polar”, especially when the analyte is aromatic (you know, that whole pi-pi thing). Also, running the tlc in an open chamber opften accelerates the vertical elution, which can lead to rings…
milkshake gets the prize
they are pretty, though!
Seems that microscopic nonuniformities on your plate are messing with the spreading dynamics of your compound. Why does coffee coalesce around the edges in a spilled drop?
First of all, use a plate with a preadsorbent zone.
Second of all, I use a cheap ass HP scanner to record my TLC plates. I circle the UV active spots (then apply I2 or ninhydrin or H2SO4 as needed), write on the plate with a #1 pencil all the compound information – instant permanent record. So if I can buy a basic scanner for $150 or so, and a UV lamp bulb for well under $100, why can’t someone figure out how to hack the scanner to use and thus record the UV of a plate? There are a couple of companies (one in France, one sketchy on in China) who want to sell you something similar for five figures. It should be trivial to cook up something that quickly records this information for parts less than 2 or 3 hundred bucks. The added benefit being that your no frills scanner is less likely to go missing from the lab or your office desk drawer than a digital camera nice enough to get an equivalent image.
Geiger turned from the hood at last and put down the empty syringe, unaware of the paradox of his death/nondeath. He unscrewed the green plastic top from a clear jar, reached in with a pair of tweezers and pulled up a flat white plate. The whiteness was made translucent almost to its top by liquid wicked up from a shallow pool at the bottom of the jar. The plate was thin glass, five by ten centimeters, and the whiteness was upon one surface only, a thin layer of silica dust. The albedo of the plate began to increase at once as the volatile liquid evaporated from the silica, helped along by his gentle breath blown thorough pursed lips against the surface, until the whole plate was a homogenous bright alabaster. Geiger then unscrewed the top of a jar identical to the first. This one was filled with purple vapor and crusted on the inside with tiny ruby-black nuggets. He carefully dropped the plate into the red fog and watched as two spots on the plate, oblong and perfectly-matched, side by side, slowly took shape and became coral and then cardinal and then maroon. At the bottom of the plate he had drawn a fine line in pencil. One spot rose straight from the line, from a region marked “sm”. Its twin rose from the mark “rxn”.
Geiger’s face was placid. He removed the plate and flicked it like a small playing card toward the window. It spun, wobbling but true, through the open portion and out into the world.
Several people have already highlighted the likely culprit of re-spotting and spreading of your compound on the TLC plate prior to developing. Another manner through which rings can form is if there is another spot that co-travels with the UV active materials, but does not light up under the lamp. I have seen this happen a few times after running a column and discovering that the little, white spot simply isn’t the result of spotting too many times, but instead was an impurity that co-eluted with my product. However, I’ve only had this happen 2-3 times with a specific set of compounds I’ve worked on.
Those are clearly the eyes of Jebus there. God speaks in mysterious ways.
I think God is speaking to Kyle about how to apply the nipple ointment in a circular motion before a marathon run – to avoid bleeding abrasions
It makes sense that Jesus continues to reach out to Kyle-
remember that Kyle saw Christ in a FID.
(one of the funniest things that I have ever read-
http://www.thechemblog.com/?p=756)
I’ve seen that too–actually it happens to be quite a bit because in certain moods I can be a really sloppy chemist. It happens (as other posters have mentioned) when I spot solvent multiple times. Usually it happens more when I’m careless and don’t spot in exactly the same place each time or let the spot dry completely before re-spotting.
That’s cool as hell! I have to agree with a couple of the previous posts. It looks like you either have Pi-Pi stacking with respect to the solvent and product, which in turn is carried with your product up the plate, but shows no staining.
Are you sure it is just one spot? Maybe you should try a different stain to see if it resolves out into two overlapping spots.
Third, try a 2-D TLC. That should answer the above question.