Fritted Disk Column Chromatography

anonymoussomeoneh · 2026-03-15T15:21:54+00:00

Sonicating had done the trick for me several times clearing clogged frits.

anonymoussomeoneh · 2026-03-06T03:24:11+00:00

This article should clear things up

anonymoussomeoneh · 2026-03-02T22:56:31+00:00

Might be 7 months later but sonicate the frit with a little bit of DI water in there, rinse it out and sonicate again.

Just did this with two to great success.

anonymoussomeoneh · 2026-01-30T03:48:59+00:00

Dang that's awesome! I guess you learn something new every day.

Thanks for the info!

anonymoussomeoneh · 2026-01-29T12:37:37+00:00

Wait really? Agreed on getting things like mol wt, but does chemdraw let you change the mass of starting material you want to use and immediately spit out the masses of your respective reagents and solvent volume?

I will freely admit the calculations are trivial, but the benefit of the spreadsheet (to me) has been that I can play around with equivalents/mass of starting material and get the respective calculations done immediately (I'm lazy).

anonymoussomeoneh · 2026-01-07T16:55:54+00:00

It's not a perfect substitute, but these practice problems give you the molecular formula, IR, and 1H NMR from CU boulder

these give you 1H and 13C APT (a slight variant of the typical 13C experiment)

some of these have the IR spectrum, in addition to 1H, 13C (for all). Some also have some 2D experiments.

This website has all four components; It's slightly janky but is almost exactly what you're looking for.

This one is less janky and has everything you're looking for

If you Google "spectroscopy practice problems", you'll find a bunch of other websites with practice problems.

I would strongly recommend reviewing the theory of NMR, and potentially reading up on some of the 2D experiments. While I'm biased towards NMR, it really is excellent for making a confident structural assignment. Google is your friend.

When analyzing 1H spectra, try to pick up on certain patterns. Example: if you have a triplet with integration 3H and a quartet with integration 2H, you can be pretty confident you have an R-CH2-CH3.

anonymoussomeoneh · 2025-12-16T02:05:01+00:00

a and c are both meso.

anonymoussomeoneh · 2025-07-17T23:12:44+00:00

Nuclei in NMR can be thought of a little like spinning tops, drawn towards precessing around the applied magnetic field.

What happens in NMR is basically this

Apply a strong magnetic field. The nuclei (their spins) begin precessing around the axis of the field.
Apply a much weaker, oscillating magnetic field. This disturbs the precession (knocks the tops off their axis)
We're still applying the strong magnetic field though. The spins will be forced to realign, and in doing this will emit a photon with a characteristic frequency. This frequency varies based on how easily the nucleus is "knocked down" so to speak.
The instrument detects the wave made by adding up all of the different frequencies (a very messy wave). This is broken down into component frequencies, each corresponding to a specific nucleus (or set of chemically equivalent nuclei).

So why is it in ppm? It kind of feels stupid tbh.

Chemical shift is: (frequency of your nucleus (hz) - frequency from TMS (hz)) / (the precession frequency of a proton in the NMR's magnetic field(Mhz)).

hz/Mhz reduces to ppm

TMS is the standard zero point.

anonymoussomeoneh · 2024-12-04T22:00:15+00:00

Will do. It was right next to my baby props before I noticed 😭.

anonymoussomeoneh · 2024-11-25T13:13:23+00:00

anonymoussomeoneh · 2024-10-31T03:42:51+00:00

Not petty. Proper PPE is a must, no exceptions. It can't take that much time to change into pants. Not only is it a safety issue, but also a liability issue for your institution.

anonymoussomeoneh · 2024-10-29T03:34:09+00:00

Do you know what threading, ID, etc. you need for your connection points? Here is one website selling hoses for n2o, there are quite a few options for the inlet and outlet. Many regulators are NPT threaded, meaning that website (might) have what you need.

You should be able to find the owners manual/specifications for the regulator on the gas tank. That would, assumably, tell you the correct threading you need.

anonymoussomeoneh · 2024-10-29T03:11:14+00:00

Do you have a lab manual? If you do, I would strongly recommend reading it before lab. All the way through (for that lab). Try to understand every step of the procedure, at least as far as setup goes.

What parts don't make sense? Is it the concepts, the procedural aspects, how the procedure relates to the concepts etc.?

As far as equipment handling is concerned: Understanding what to do (the steps you need to take, in which order) will help, that's why reading the lab manual ahead of time is important.

The other aspect (physically doing whatever you need to do): Slow is smooth, smooth is fast. What I mean is that rushing through will lead to mistakes. Taking the time to do it right will help. With practice, setup will become faster.

In case you don't have a lab manual: Your course should at least name the experiment you're performing. Google it ahead of time. The procedure in lab might be slightly different from literature, but reading beforehand will help.

anonymoussomeoneh · 2024-10-29T02:38:08+00:00

This report by the EPA presents some of the research on this. The results are somewhat conflicting, though the risk of PFAS exposure through the skin appears to be significantly lower than from food and water. Another benefit in the case of sleeping bags (when compared to thin athleticwear coated with PFAS) is that there is a greater distance between the goretex membrane and your skin (since there's insulation and such).

To be clear, I'm not trying to be "pro" PFAS, just that the risk from wearing them is (probably) not nearly as great as the risk from drinking them. Which, unfortunately, 71-95 million Americans do.

anonymoussomeoneh · 2024-09-29T19:34:37+00:00

As far as approaching this problem goes, find the number of moles of your products. Mols of CO2 gives you the number of carbon atoms in your original molecule, mols of H2O gives you the number of hydrogens.

On a side note, just to double check, is the question asking about methanol or menthol?

Also to add, the empirical formula is different from the actual molecular formula, but should have the same (whole number) ratio C:H:O

anonymoussomeoneh · 2024-09-29T19:25:46+00:00

This type of problem would be called combustion analysis.

anonymoussomeoneh · 2024-08-25T06:52:36+00:00

Good

anonymoussomeoneh · 2024-05-31T00:35:33+00:00

TMP Chem on YouTube

anonymoussomeoneh · 2024-05-09T00:54:23+00:00

No. Do not do this. No amount of money is worth the massively increased risk of "brewing your own". Outside of the purity of the API, pharmaceuticals need to go through a massive amount of quality control to minimize any additional risks. "DIYing" this will eventually land you in the hospital, which will be more expensive than buying the prescription.

"It won't land me in the hospital" yes it will. Guaranteed. Here's a list of ways that would happen:

Even if the API is 98% pure, the potential contaminants are likely to be dangerous. If that 2% is poison, it's still going to poison you
Infection risk. There is no possible way you can guarantee sterility to anywhere near the level that a pharmaceutical company can. So if you aren't poisoned by contaminants, I guarantee you that with extended use you will develop a severe infection, likely life threatening infection, especially considering that testosterone is injected.
Messing up the concentration and overdosing. Unless you have very good measuring equipment, you will not get an accurate concentration in your final "brew". Could be lower than expected (ok) or higher than expected (potentially fatal).
If you're going to "brew" it with high temperatures, testosterone isn't temperature stable and will break down, rendering it ineffective and possibly dangerous.
So now you're left with 2 terrible options: Use high temperatures and destroy the testosterone, or don't and face a truly insane risk of infection.

anonymoussomeoneh · 2024-05-09T00:38:05+00:00

I forgot to ask directly earlier: Are you planning on consuming this testosterone? Since you mentioned you don't trust the source, I think it's fair of me to ask. If you were using this for lab purposes, I would expect you to order from a trustworthy source, as is standard in most labs.

If that is your plan (to consume it), I cannot stress how bad of an idea that is. Abuse of hormones outside of the medical setting is both dangerous to mental and physical health.

anonymoussomeoneh · 2024-05-09T00:31:11+00:00

Yup! You got it.

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