4 ms·

> Join us for our continued lecture series, covering topics such as Please share/blog these! I too have several degenerate chemistry undergrad stories. > The

by kortex 4y ago

> Join us for our continued lecture series, covering topics such as Please share/blog these! I too have several degenerate chemistry undergrad stories. > The poor efficacy of DMSO in assisting drug translocation through skin Yep. During one particularly sleep-deprived finals week, and after recently learning about DMSO's transdermal transportation abilities, my friend and I tried making caffeine skin patches. It worked...vaguely increasing alertness. However, it itched and burned worse than just about anything I've ever experienced. Also I can concur that chloroform isn't some instant knock-out juice. But one time, a lab mate and I were running massive columns and had accumulated several hundred liters of DCM (dichloromethane) fractions in flasks (yes, it was a loong day). Despite the walk-in hoods running at full bore, by the end of the day, coworker and I were loopy, giggly idiots. Was it above OSHA PEL? Possibly, but probably not. I think the disinhibition was a combination of energy drinks, fatigue+boredom of running hundreds of fractions, and suggestibility, as much as it was the fumes. But my lab manager did walk in at one point and immediately recoiled from the fumes (which we were nose-deaf to at that point).

zoklet-enjoyer 4y ago
You have to really dilute DMSO if you're going to put it on your skin.
- kortex 4y ago
  I mean, pure DMSO on the skin feels fine, albeit not the safest.
  - throwawaymaths 4y ago
    Can you not taste the garlic in your mouth for hours after?
    - ta988 4y ago
      Not everybody does.
joosters 4y ago
But my lab manager did walk in at one point and immediately recoiled from the fumes (which we were nose-deaf to at that point). I don't know whether it's true or not, but I remember a chemistry lecturer telling me that you don't need to worry about terrible smells in the lab, our noses are sensitive to extremely miniscule levels of chemicals. It's when the levels are so high that they have overpowered our senses and knocked out our sense of smell, that's when you need to worry! A wonderfully paradoxical piece of advice...
- somebodynew 4y ago
  Hydrogen sulfide is a severe example: it initially smells strongly of rotten eggs but quickly damages the nose until it is undetectable and further exposure can be lethal. For most other chemicals, smells only fade to the background during prolonged lab work through mundane desensitization.
- kortex 4y ago
  More or less, but with caveats. It's true that many smells (eg H2S, HCN) are detectable before toxic levels, and then become un-smellable at higher levels (saturates and depletes olfactory receptors). But you should still worry about certain terrible smells, because that's often the first sign that something is going wrong. Containment failure, reaction runaway, maybe someone dumped the wrong thing in the wrong waste barrel and now it's reacting, etc. There's also things which are toxic at the same levels as olfaction, and of course there toxins which are dangerous by the time you have smelled them, or you lack the gene to smell. Most really smelly things aren't acutely toxic like that though. Take DMS (dimethyl sulfide, byproduct of Swern oxidation. Smells like boiling cabbage at low concentration, and liquid ass at high concentration. If you are running a Swern in a fume hood, you are likely quite well-contained even if you've made the whole lab smell like a cesspit. When we ran cyanation at the kilo scale, you better believe we had HCN detectors all over the place, wore full-face respirators, etc.
  - jamesash 4y ago
    I pass along this amusing advice, no doubt familiar to you, but probably not to the general HN readership. "Gattermann (Ann. 357, 318 (1907)) recommends that the operator smoke during the preparation [of HCN], for he found that a trace of hydrogen cyanide is sufficient to give the tobacco smoke a highly characteristic flavor. This preliminary warning is useful in case of leaky apparatus or a faulty hood" - from Org Syn http://www.orgsyn.org/demo.aspx?prep=CV1P0314 http://www.orgsyn.org/demo.aspx?prep=CV1P0314
FPGAhacker 4y ago
[flagged]
mschuster91 4y ago
> But my lab manager did walk in at one point and immediately recoiled from the fumes (which we were nose-deaf to at that point). Reminds me of NileRed's attempts to create enormously stinky substances [1][2]. In one of the videos he said he's basically smell-blind. [1] https://www.youtube.com/watch?v=C_eYLWLsWPg https://www.youtube.com/watch?v=C_eYLWLsWPg [2] https://www.youtube.com/watch?v=LmAG8-V_WQY https://www.youtube.com/watch?v=LmAG8-V_WQY

by kortex 4y ago

zoklet-enjoyer 4y ago

You have to really dilute DMSO if you're going to put it on your skin.

kortex 4y ago
I mean, pure DMSO on the skin feels fine, albeit not the safest.
- throwawaymaths 4y ago
  Can you not taste the garlic in your mouth for hours after?
  - ta988 4y ago
    Not everybody does.

joosters 4y ago

But my lab manager did walk in at one point and immediately recoiled from the fumes (which we were nose-deaf to at that point). I don't know whether it's true or not, but I remember a chemistry lecturer telling me that you don't need to worry about terrible smells in the lab, our noses are sensitive to extremely miniscule levels of chemicals. It's when the levels are so high that they have overpowered our senses and knocked out our sense of smell, that's when you need to worry! A wonderfully paradoxical piece of advice...

somebodynew 4y ago
Hydrogen sulfide is a severe example: it initially smells strongly of rotten eggs but quickly damages the nose until it is undetectable and further exposure can be lethal. For most other chemicals, smells only fade to the background during prolonged lab work through mundane desensitization.
kortex 4y ago
More or less, but with caveats. It's true that many smells (eg H2S, HCN) are detectable before toxic levels, and then become un-smellable at higher levels (saturates and depletes olfactory receptors). But you should still worry about certain terrible smells, because that's often the first sign that something is going wrong. Containment failure, reaction runaway, maybe someone dumped the wrong thing in the wrong waste barrel and now it's reacting, etc. There's also things which are toxic at the same levels as olfaction, and of course there toxins which are dangerous by the time you have smelled them, or you lack the gene to smell. Most really smelly things aren't acutely toxic like that though. Take DMS (dimethyl sulfide, byproduct of Swern oxidation. Smells like boiling cabbage at low concentration, and liquid ass at high concentration. If you are running a Swern in a fume hood, you are likely quite well-contained even if you've made the whole lab smell like a cesspit. When we ran cyanation at the kilo scale, you better believe we had HCN detectors all over the place, wore full-face respirators, etc.
- jamesash 4y ago
  I pass along this amusing advice, no doubt familiar to you, but probably not to the general HN readership. "Gattermann (Ann. 357, 318 (1907)) recommends that the operator smoke during the preparation [of HCN], for he found that a trace of hydrogen cyanide is sufficient to give the tobacco smoke a highly characteristic flavor. This preliminary warning is useful in case of leaky apparatus or a faulty hood" - from Org Syn http://www.orgsyn.org/demo.aspx?prep=CV1P0314 http://www.orgsyn.org/demo.aspx?prep=CV1P0314

FPGAhacker 4y ago

[flagged]

mschuster91 4y ago

> But my lab manager did walk in at one point and immediately recoiled from the fumes (which we were nose-deaf to at that point). Reminds me of NileRed's attempts to create enormously stinky substances [1][2]. In one of the videos he said he's basically smell-blind. [1] https://www.youtube.com/watch?v=C_eYLWLsWPg https://www.youtube.com/watch?v=C_eYLWLsWPg [2] https://www.youtube.com/watch?v=LmAG8-V_WQY https://www.youtube.com/watch?v=LmAG8-V_WQY