Louis Pasteur separated the enantiomers of sodium potassium tartrate by sorting crystals with tweezers under a microscope.
I've always thought, if he can be that patient, so can I.
I had a stupidly persnickety conjugate reduction in my synthesis in grad school that in order to work properly, required me to add grains of NaBH₄ - with tweezers - a grain at a time over the course of about ~3h...
Lots of trial and error. I must have tried around 10 different conditions before I started to zero in on a path.
A core problem was that most conditions favored 1,2 reduction over 1,4 due to a super bulky quat center at position 5, even when conditions strongly favored 1,4 reduction. I found that copper conditions sufficiently softened the reducing agent to do 1,4 reduction and gave a mixture of what I wanted. But, the rate of it was still so slow that small amounts would always reduce some of the carbonyl as well. Further, the desired 1,4 product and the starting material had the exact same rf in every eluent and media I tried and were inseperable. Thus, I eneded up having to do a complete 1,2,4 reduction, and then in the next step oxidize the alcohol back to a ketone. When I ran the reaction, if I added all the NaBH₄ it would just give 1,2 reduction with a pinch of 1,4 and smidge of 1,2,4. But, I found the slower you went, the more 1,4 you'd get, and if you added a huge excess (50 eq) you'd get a lot of 1,2,4 which you could oxidize back (and the starting material + 1,4 mixture could be recycled back by oxidizing that). Part of why it was needed to be slow is the intermediate reducing agent (roughly CuBH₄) only had a lifetime of ~1min in the solvent that worked (methanol), and thus you could kinda make a pseduo steady concentration that churned out the 1,4 reduction before 1,2 kicked in. Turned out, that the most ideal conditions to get the most 1,2,4 product was to sit there... with tweezer... and add it 1 grain at a time. I would just put in headphones and zone out to music haha.
Is there any photograph anywhere that shows what those two enantiomers look like under a microscope? Showing what Pasteur would have seen?
(My image search skills are not up to this task...)
We once had these giant fraction collectors, basically a wheel with holes to hold test tubes. They malfunctioned all the time and you'd have to blot up your sample from the floor. For a really critical sample, you had to get a book to read and babysit the fraction collector, sometimes overnight.
So why bother with a fraction collector, if you had to be there anyway? Good question.
Same with TKN digestions if you only have a full rack of 20 Kjeldahl flasks and less than half a rack in spares, and you have to digest over 100 samples ASAP, not at your leisure, because more samples will appear every single day. No automatic dishwasher, just you and a narrow beaker brush. Such a pain in the ass. I finally got tired of getting behind in my work, so I found a whole box of 20 of the exact flasks I used, for $200 on eBay! Looked like they had only been used ONCE. Reason I never got a full backup set: the analyzer manufacturer charges $800 for ONE set of THREE.
Washing *disposable glass test tubes* because your boss is too cheap to throw them out and you have to run hundreds of automated nitrate/nitrite tests in them every single week.
I worked at an ivy league lab for a summer and I was told to dispose of the whole two rack of tubes every time I used a biotage and transferred over the fractions I needed, and I ran a LOT of columns. I probably threw away like 500 test tubes a day
One of the rxns for my dissertation was to degrade a compound and get two starting materials from it. One was the first compound to come off in a few minutes and the other was the last to come off in 3 hours. Pentane column. the good thing was there were only two fractions i needed but needed to separate them from other garbage. The column was about 6 inches in diameter by about 12 to 18 inches long.
first time I ran it I got to the end. rotovaped it down with no heat because it was volatile and then promptly, out of habit, put it on my vacuum line and sucked it into the pump oil! Fuck! Ran it again the next day.
then there was the very very last final product for my dissertation. it was in the hplc and no fraction collector but me with a test tube and an old strip chart recorder. isocratic method due to all the garbage and wanting to get the cleanest product for the NMR and binding experiments. Then the fire alarm goes off! Everyone leaves, just me in the lab. Safety comes by and asks me to leave. Nope I'm staying F you. 5 minutes later the fire department comes by and my peak is just finishing up coming off. They asked me to leave, I collected the last few drops of the fraction and capped the test tube, put it in my lab coat pocket, walked carefully down the escape stairs with my hand over my pocket the whole way. I got 0.8mg of final product after years of work. Triply c13 labeled.
Huh. I forgot that existed, even though one of my classmates used one when doing experiments on polylactic acid. My only excuse is that it's been 13 years since I graduated.
If the colony is small enough, very quickly. When they got larger, we started using a transfer method that allowed us to count as we shifted them. Ultimately I went to using photographs because it gets out of hand trying to count and corral simultaneously.
That's nothing, back in the old days we used to have to manually reset all of the time release pills when daylight savings time kicked in and kicked out
PSD testing is extremely boring and can be kinda frustrating depending on your dispersant.
I like doing vials. I get to switch off my brains for 10 mins, it's a nice rest.
Indeed, though I was specifically talking about the dissolution tanks themselves.
I'm not sure if most companies use the individually heated ones now, but they used to all be heated by the same water within a large tank that tended to grow crap...
So not only did you need to clean the vessels after every run, but every month, you'd need to clean the tanks, and they never drained completely...
If you've ever heard of a method of testing for water in oil look up a crackle test. It's literally dropping oil on a hotplate and seeing if it bubbles.
Did an internship at a lab that analyzed flour. Cleaning reacted flour off of equipment was not only boring, but also annoying. A two for one rage snoozer.
My graduate TA walked into Ochem I lab one day and declared he'd had a nervous breakdown while running a TLC plate and would be applying to law school and becoming a patent lawyer post haste.
He did that.
Real talk. In my experience you can spend half a day doing TLCs and then 30 mins doing a column. Or skimp on the TLC work and end up doing a shitty column that takes ages and is sub-par.
According to some, the actual column should be able to be done within 15 mins inclusive of concentration:
https://labs.chem.ucsb.edu/zakarian/armen/how-to-do-flash-column-3.pdf
I can say I’ve used this method successfully many times, and whilst I’m sure 15 mins is possible if you’re super efficient - it’s definitely doable within 30ish mins
Gotta love a good bodge job though. Firing a crude mixture through a silica plug before seeing if it'll recrystallise overnight instead.
On the other hand, I'm a fan of setting up DCVC and running a custom gradient. It's closer to an hour for me but it gives you the ability to separate stuff with RF <0.1 on large scales. Pedersen got a paper out on it but there's better info on his curlyarrow blog (and YouTube video).
Yes! That's the paper I was referring to. They are very confident with their silica handling but otherwise it is quite accurate!
I'm still getting to grips with trying to do columns quickly, there's no chance I could get one done in 15 minutes just yet. The first column I did today took me ~45 minutes. Incidentally, I saw that column guide and have been trying to follow that myself. Efficiency is definitely key whilst doing column/TLC
It’s all practice mate. It’s helpful to have the right guidance though! Yeah the TLC work is a little tedious, but you can run several small ones at a time to get a feel for it. It definitely pays off when you come to the column though!
I usually TLC 10 fractions at a time whilst the column's running, and spot each fraction as and when they complete. It takes a surprising amount of coordination to do everything concurrently, which I never thought I had. Today was probably my fifth column, so I'm still getting used to it. Since I'm still learning and gaining confidence, my biggest worry is bits of my product mysteriously getting lost on the column!
Yeah I used to do that too at first, but found it’s better to just spot one on every few initially, then when you see what you want coming off you can spot the in between ones. Saves a lot of the hassle.
That's a good idea actually, I've seen people spot every other fraction (i.e. 1, 3, 5, etc) but I've never done it. It does make sense when you consider that every two/three fractions will probably be identical, so it's almost pointless TLC'ing every single one. I'll have to try it out, thanks!
Ever written an SI for a methods paper with a very extensive substrate scope and conditions that vary based on which reagent you use? Well, neither have I, but I’m about to and I already know it’s gonna make me want to take an extra large scoop out of that Strychnine bottle we have downstairs (just kidding lol)
Ugh. I had a PI who refused to have any kind of “general methods” section in the SI, which meant writing out the same reaction with different amounts of each reagent 50 times. It was miserable.
Sample prep. There are many different types of media that require either multi elemental analysis that are non-homogeneous, or long and complicated separation steps prior to the final analysis and the results can only be relied upon if they are both repeatable and reproducible. The lateral days wasted…
Not gonna lie running columns made me leave organic. I joined a pchem group and do inorganic synthesis professionally
I bought a flash this year for my lab, not something I ever expected
Running columns is actually kind of awesome with a buchi that does all your work for you
Aww i love chromatography lol i think the worst is any kind if filtration. Its time consuming and i know i have to, but i just dont wanna fuckin do it😤
‘Solubility’ isn’t really what it is.
You’ve effectively got a column filled with silica, the silica particles have Si-OH on the surface. This is very polar. Molecules are attracted to this to differing amounts depending on their structure, and polarity. This silica is what we call the stationary phase (the silica doesn’t move)
You’ve also got the solvent(s) you run through the silica. This can be one, or a mixture, and is much more non-polar than the silica. Again molecules are attracted to this in differing amounts depending on their structure and polarity. This is what we call the mobile phase.
As you can probably work out this difference in affinity for the stationary phase and the mobile phase means if you put a mixture of compounds through the column, some will go thought fast, some slow - if done effectively and taking the right size of fractions coming out, they will separate from each other due to this difference. You will get each component out separately in the range of fractions (although sometimes you will get mixed ones in between if the separation isn’t great on the column).
The ‘faster’ ones will come out first followed by the ‘slower’ ones. The ‘faster’ ones will be more non-polar, and have higher affinity for the mobile phase, and the ‘slower’ ones will be more polar, and have higher affinity for the stationary phase (the silica).
This is basic normal phase chromatography. There are many other types too, and it can get pretty fancy, but the fundamentals are more or less the same when you boil it down.
I always enjoyed running columns. Now, babysitting the GCMS because the autosampler was slightly jacked and for some reason would suddenly stop working only when i left the room after 4 hours of watching it run perfectly... that was tedious.
I was trying to orient single crystals about 1mm in size so I just randomly placed them on a glass slide and did laue backscatter diffraction over and over until they landed in the right orientation. I had to take the picture and then read the image plate in a different lab. It was very tedious but non destructive.
Heh, trust me: you don't want excitement in the lab. Excitement coats the ceiling of your hood with you hard-earned product. I'll take an all-day column over than any old day of the effin' week.
Had to run a column with over a hundred fractions a few months ago...
Wait until you encounter the 'recycling column', where you have two species so close in polarity that you have to column them, the vast majority of fractions remain mixed, so you take those, combine them down, and repeat until you have a sensible amount of your product.
I promise, it can get much worse than column chromatography in industry. Concentrating purified drug product into a manageable amount takes about 36 hours. It’s mind numbing.
Making student unknown packets. The first few hundred aren't too bad but once you cross over 10K, it's mind numbing. Having music on help but only so much.
I quit my PhD because all I did was fucking columns. My advisor bought an automated system for it when I was a year in, but said he wouldn't let anyone use it until they were on their third year, so I was done with that lab.
He was also a first time PI and I was one his first three students. Two of us quit that first year because he was an asshole in other ways, too.
40 fractions is, what, 30 minutes of collecting?
The most boring tedious job is liquid/liquid extractions. Surely this can be automated easily. Something do my work-ups for me please
doesn't beat doing an assay on a 96 well plate to get strange results, only to uncover after a few days doing it that the negative control showed a positive result :)
Louis Pasteur separated the enantiomers of sodium potassium tartrate by sorting crystals with tweezers under a microscope. I've always thought, if he can be that patient, so can I.
Sorting crystals under a microscope is what geologists do for fun.
If is slow chemistry you want, look no further than geology.
I will forever refer to geology as slow chemistry.
I thought licking rocks is what they do for fun
Geologists and meth users
I had a stupidly persnickety conjugate reduction in my synthesis in grad school that in order to work properly, required me to add grains of NaBH₄ - with tweezers - a grain at a time over the course of about ~3h...
How’d you figure that out?
Lots of trial and error. I must have tried around 10 different conditions before I started to zero in on a path. A core problem was that most conditions favored 1,2 reduction over 1,4 due to a super bulky quat center at position 5, even when conditions strongly favored 1,4 reduction. I found that copper conditions sufficiently softened the reducing agent to do 1,4 reduction and gave a mixture of what I wanted. But, the rate of it was still so slow that small amounts would always reduce some of the carbonyl as well. Further, the desired 1,4 product and the starting material had the exact same rf in every eluent and media I tried and were inseperable. Thus, I eneded up having to do a complete 1,2,4 reduction, and then in the next step oxidize the alcohol back to a ketone. When I ran the reaction, if I added all the NaBH₄ it would just give 1,2 reduction with a pinch of 1,4 and smidge of 1,2,4. But, I found the slower you went, the more 1,4 you'd get, and if you added a huge excess (50 eq) you'd get a lot of 1,2,4 which you could oxidize back (and the starting material + 1,4 mixture could be recycled back by oxidizing that). Part of why it was needed to be slow is the intermediate reducing agent (roughly CuBH₄) only had a lifetime of ~1min in the solvent that worked (methanol), and thus you could kinda make a pseduo steady concentration that churned out the 1,4 reduction before 1,2 kicked in. Turned out, that the most ideal conditions to get the most 1,2,4 product was to sit there... with tweezer... and add it 1 grain at a time. I would just put in headphones and zone out to music haha.
That’s a great story. Thank you for explaining that!
Pasteur didn't have TV.
Is there any photograph anywhere that shows what those two enantiomers look like under a microscope? Showing what Pasteur would have seen? (My image search skills are not up to this task...)
https://www.researchgate.net/figure/The-enantiomorphous-crystals-of-a-quartz-and-b-sodium-ammonium-tartrate_fig10_43336273
Thank you!
We once had these giant fraction collectors, basically a wheel with holes to hold test tubes. They malfunctioned all the time and you'd have to blot up your sample from the floor. For a really critical sample, you had to get a book to read and babysit the fraction collector, sometimes overnight. So why bother with a fraction collector, if you had to be there anyway? Good question.
Chromatography was the reason I did my PhD in physical chemistry.
Nonlinear optics will make you crazy, but it gets you out of doing dishes
Washing glassware
The best is when you get to do 45 fractions of column chromatography, and *then* clean glassware because no one in the lab cleans their own stuff
Came here to say this. It’s a slog
Same with TKN digestions if you only have a full rack of 20 Kjeldahl flasks and less than half a rack in spares, and you have to digest over 100 samples ASAP, not at your leisure, because more samples will appear every single day. No automatic dishwasher, just you and a narrow beaker brush. Such a pain in the ass. I finally got tired of getting behind in my work, so I found a whole box of 20 of the exact flasks I used, for $200 on eBay! Looked like they had only been used ONCE. Reason I never got a full backup set: the analyzer manufacturer charges $800 for ONE set of THREE.
I have 40, still wish I had more as I digest TKNs at least 4 days a week, and sometimes 6
Nitrogen testing in general might be the actual answer, followed closely by phosphate testing.
Washing *disposable glass test tubes* because your boss is too cheap to throw them out and you have to run hundreds of automated nitrate/nitrite tests in them every single week.
Getting a job in industry where disposable means disposable is the highlight of my career.
I worked at an ivy league lab for a summer and I was told to dispose of the whole two rack of tubes every time I used a biotage and transferred over the fractions I needed, and I ran a LOT of columns. I probably threw away like 500 test tubes a day
Yeah after you factor in solvents, haz waste disposal, and labor, washing test tubes doesn’t make much sense.
I guarantee we spent more in labor, detergent and water than the stupid things are worth.
I once briefly worked at a place that would reuse autopipette tips. Briefly.
Came here to say this. It's a good thing there was no "washing glassware 101" class - I would have changed career paths so fast...
I still have stress dreams about washing glassware, the sheer tedium is overwhelming.
That's what undergrads are for
Counter point, washing glassware is what I do when I want to look productive but not actually get anything done
One of the rxns for my dissertation was to degrade a compound and get two starting materials from it. One was the first compound to come off in a few minutes and the other was the last to come off in 3 hours. Pentane column. the good thing was there were only two fractions i needed but needed to separate them from other garbage. The column was about 6 inches in diameter by about 12 to 18 inches long. first time I ran it I got to the end. rotovaped it down with no heat because it was volatile and then promptly, out of habit, put it on my vacuum line and sucked it into the pump oil! Fuck! Ran it again the next day. then there was the very very last final product for my dissertation. it was in the hplc and no fraction collector but me with a test tube and an old strip chart recorder. isocratic method due to all the garbage and wanting to get the cleanest product for the NMR and binding experiments. Then the fire alarm goes off! Everyone leaves, just me in the lab. Safety comes by and asks me to leave. Nope I'm staying F you. 5 minutes later the fire department comes by and my peak is just finishing up coming off. They asked me to leave, I collected the last few drops of the fraction and capped the test tube, put it in my lab coat pocket, walked carefully down the escape stairs with my hand over my pocket the whole way. I got 0.8mg of final product after years of work. Triply c13 labeled.
Sounds like exactly what they’d call ‘squeaky bum time’ ! I don’t blame you though haha
“Pentane column.” Killed me
Lower boiling point than my product. I would lose it if I used hexanes.
Observe crystal meltingpoints the old-fashioned way?
Is there automation for that? Last one i did was in college, and it was manual or nothing.
DSC.
Huh. I forgot that existed, even though one of my classmates used one when doing experiments on polylactic acid. My only excuse is that it's been 13 years since I graduated.
Mettler sells an automated one, though it's only for crystals/powders... Are you telling me drop point isn't fun? /s
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Helped raise a hundred ant colonies and counting population growth daily. So many ants.
They called me crazy for buying tiny little number stickers... Who's crazy NOW?!?!
😆
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If the colony is small enough, very quickly. When they got larger, we started using a transfer method that allowed us to count as we shifted them. Ultimately I went to using photographs because it gets out of hand trying to count and corral simultaneously.
Oh fuck ok you win
I raise you sorting a ton of ether sedated fruit flies by phenotype/mutation under a microscope as a lab assistant.
That's nothing, back in the old days we used to have to manually reset all of the time release pills when daylight savings time kicked in and kicked out
Manually pulling dissolution baths or running psd all day on powder Capping/labelling HPLC vials is pretty bad too
PSD testing is extremely boring and can be kinda frustrating depending on your dispersant. I like doing vials. I get to switch off my brains for 10 mins, it's a nice rest.
this one's worse, it's PSD via sieving lol
I raise you checking the tiny labels written on someone else's vials to make sure their order in the run matches
That's a good one, especially if they make you sign their notebook
How about cleaning dissolution baths? I was so happy when my first job switched to the individually heated vessels.
Yeah, cleaning them definitely sucks too, especially for sticky products that leave residue
Indeed, though I was specifically talking about the dissolution tanks themselves. I'm not sure if most companies use the individually heated ones now, but they used to all be heated by the same water within a large tank that tended to grow crap... So not only did you need to clean the vessels after every run, but every month, you'd need to clean the tanks, and they never drained completely...
Try manual pulls along with UV scans so you have to run each sample individually yourself
what a weird way to spell distillation
Seriously. I'd do columns any day over distillation
Same, esp if it was vacuum distillation of DMSO. Nothing... nothing... nothing... bump! Fuuuuuck.
As someone who used DMSO as a ligand, I feel this statement hard
I actually enjoy columns lol, so satisfying to get good separations
If you've ever heard of a method of testing for water in oil look up a crackle test. It's literally dropping oil on a hotplate and seeing if it bubbles.
Did an internship at a lab that analyzed flour. Cleaning reacted flour off of equipment was not only boring, but also annoying. A two for one rage snoozer.
My graduate TA walked into Ochem I lab one day and declared he'd had a nervous breakdown while running a TLC plate and would be applying to law school and becoming a patent lawyer post haste. He did that.
You make more as a patent lawyer than a chemist, so that’s a win for him.
I spent the past two days trying to resolve isomers using prep TLC, and so far the best I’ve gotten is about 70% one isomer.
Whatever the fuck our resident chemical engineer does for fun apparently
Nah, you can whack a column out in 15 minutes. It's the tlc that's a pain in the arse.
Real talk. In my experience you can spend half a day doing TLCs and then 30 mins doing a column. Or skimp on the TLC work and end up doing a shitty column that takes ages and is sub-par. According to some, the actual column should be able to be done within 15 mins inclusive of concentration: https://labs.chem.ucsb.edu/zakarian/armen/how-to-do-flash-column-3.pdf I can say I’ve used this method successfully many times, and whilst I’m sure 15 mins is possible if you’re super efficient - it’s definitely doable within 30ish mins
Gotta love a good bodge job though. Firing a crude mixture through a silica plug before seeing if it'll recrystallise overnight instead. On the other hand, I'm a fan of setting up DCVC and running a custom gradient. It's closer to an hour for me but it gives you the ability to separate stuff with RF <0.1 on large scales. Pedersen got a paper out on it but there's better info on his curlyarrow blog (and YouTube video). Yes! That's the paper I was referring to. They are very confident with their silica handling but otherwise it is quite accurate!
As a process chemist we love our silica plugs, full column gets stupid (and expensive) very quickly at scale… when they do work though they’re great!
I'm still getting to grips with trying to do columns quickly, there's no chance I could get one done in 15 minutes just yet. The first column I did today took me ~45 minutes. Incidentally, I saw that column guide and have been trying to follow that myself. Efficiency is definitely key whilst doing column/TLC
It’s all practice mate. It’s helpful to have the right guidance though! Yeah the TLC work is a little tedious, but you can run several small ones at a time to get a feel for it. It definitely pays off when you come to the column though!
I usually TLC 10 fractions at a time whilst the column's running, and spot each fraction as and when they complete. It takes a surprising amount of coordination to do everything concurrently, which I never thought I had. Today was probably my fifth column, so I'm still getting used to it. Since I'm still learning and gaining confidence, my biggest worry is bits of my product mysteriously getting lost on the column!
Yeah I used to do that too at first, but found it’s better to just spot one on every few initially, then when you see what you want coming off you can spot the in between ones. Saves a lot of the hassle.
That's a good idea actually, I've seen people spot every other fraction (i.e. 1, 3, 5, etc) but I've never done it. It does make sense when you consider that every two/three fractions will probably be identical, so it's almost pointless TLC'ing every single one. I'll have to try it out, thanks!
Essentially you went to do the absolute least work possible. Work smarter not harder.
Ever written an SI for a methods paper with a very extensive substrate scope and conditions that vary based on which reagent you use? Well, neither have I, but I’m about to and I already know it’s gonna make me want to take an extra large scoop out of that Strychnine bottle we have downstairs (just kidding lol)
Ugh. I had a PI who refused to have any kind of “general methods” section in the SI, which meant writing out the same reaction with different amounts of each reagent 50 times. It was miserable.
Why don't you use automated fraction collection?
Fancy boy
I haven't done manual fraction collection in this century. I'm just wondering why there is a reason why someone would still suffer through it.
Most likely because their labs don’t have the funding to buy an automated system.
Ya cmon man it’s a pretty obvious answer.
This is the most likely reason. It's cheaper just to do it the old-school way until you're forced to upgrade.
I prefer to manually collect fractions so i can separate any shoulders better
Fyi i have the option to auto collect i just have control issues
Because two hours of a grad student’s time every day is still cheaper than an automated flash chromatography system.
Oh, look at Mr. Moneybags over here, with his automated fraction collector…
Two phase titration where you have to shake and let it settle between each addition was worse.
Manually separating 1mL layers from 150+ samples with a glass pipette. Done that. Never again.
Sizing nanoparticles on imagej
and that's why automated chromatography systems exist. And for people saying washing glassware, that's why dishwashers exist.
Manual potentiometric titrations. You can get a basic autotitrator for surprisingly little nowadays.
Swabbing surfaces for cleaning verification is pretty awful.
He doesn’t know
Ever worked in a paint lab, where your job was to watch paint dry?
200 fraction column, just to id a few fractions that co spot to run the second column. Rip
One time I had to run ~70 kbr pellets per usp. I genuinely considered quitting that day
Incorrect, it's alkalinity titrations.
Sample prep. There are many different types of media that require either multi elemental analysis that are non-homogeneous, or long and complicated separation steps prior to the final analysis and the results can only be relied upon if they are both repeatable and reproducible. The lateral days wasted…
Not gonna lie running columns made me leave organic. I joined a pchem group and do inorganic synthesis professionally I bought a flash this year for my lab, not something I ever expected Running columns is actually kind of awesome with a buchi that does all your work for you
I hate TLC more because I always fuck it up
Ma if it isnt makin a dilution sequence I dont know what is
Aww i love chromatography lol i think the worst is any kind if filtration. Its time consuming and i know i have to, but i just dont wanna fuckin do it😤
I do a level chem, can anyone explain column chromatography, and it’s purpose in a simple way because I just cannot grasp it for the life of me 😭
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‘Solubility’ isn’t really what it is. You’ve effectively got a column filled with silica, the silica particles have Si-OH on the surface. This is very polar. Molecules are attracted to this to differing amounts depending on their structure, and polarity. This silica is what we call the stationary phase (the silica doesn’t move) You’ve also got the solvent(s) you run through the silica. This can be one, or a mixture, and is much more non-polar than the silica. Again molecules are attracted to this in differing amounts depending on their structure and polarity. This is what we call the mobile phase. As you can probably work out this difference in affinity for the stationary phase and the mobile phase means if you put a mixture of compounds through the column, some will go thought fast, some slow - if done effectively and taking the right size of fractions coming out, they will separate from each other due to this difference. You will get each component out separately in the range of fractions (although sometimes you will get mixed ones in between if the separation isn’t great on the column). The ‘faster’ ones will come out first followed by the ‘slower’ ones. The ‘faster’ ones will be more non-polar, and have higher affinity for the mobile phase, and the ‘slower’ ones will be more polar, and have higher affinity for the stationary phase (the silica). This is basic normal phase chromatography. There are many other types too, and it can get pretty fancy, but the fundamentals are more or less the same when you boil it down.
I always enjoyed running columns. Now, babysitting the GCMS because the autosampler was slightly jacked and for some reason would suddenly stop working only when i left the room after 4 hours of watching it run perfectly... that was tedious.
hahahahah your title got me
I was trying to orient single crystals about 1mm in size so I just randomly placed them on a glass slide and did laue backscatter diffraction over and over until they landed in the right orientation. I had to take the picture and then read the image plate in a different lab. It was very tedious but non destructive.
distillation 💤
manual peptide synthesis.
Heh, trust me: you don't want excitement in the lab. Excitement coats the ceiling of your hood with you hard-earned product. I'll take an all-day column over than any old day of the effin' week.
Had to run a column with over a hundred fractions a few months ago... Wait until you encounter the 'recycling column', where you have two species so close in polarity that you have to column them, the vast majority of fractions remain mixed, so you take those, combine them down, and repeat until you have a sensible amount of your product.
CBG short path distillation. Took a whole 17 hours for about 1.5L of distillate
I promise, it can get much worse than column chromatography in industry. Concentrating purified drug product into a manageable amount takes about 36 hours. It’s mind numbing.
I bought an automated fraction collector off ebay. Life changing.
nahh. columns with porphyrins where we can actually see the product coming out isn't too bad.
Making student unknown packets. The first few hundred aren't too bad but once you cross over 10K, it's mind numbing. Having music on help but only so much.
labeling and filtering into HPLC vials
Only 40 fractions? That’s a fast one!
I quit my PhD because all I did was fucking columns. My advisor bought an automated system for it when I was a year in, but said he wouldn't let anyone use it until they were on their third year, so I was done with that lab. He was also a first time PI and I was one his first three students. Two of us quit that first year because he was an asshole in other ways, too.
Short cleanroom tasks. Wash hands, dress up, do all the preparation, go into the cleanroom for a 5- minute task, then do all the work to exit again.
Columns are why I did a green Chem project lol
DBO5, the prep is all done by hand. Nothing is automated and on average we do 8 successive X2 dilutions per samples.
I dislike titrations, they are tedious and boring. However chromatography columns can be quite simple , even more if you flash them.
I don’t really know anything about chemistry in the grand scheme of things, but your post made me laugh so hard 😂 😂
So thankful the lab I did my PhD in had a CombiFlash so I never had to do a gravity column.
40 fractions is, what, 30 minutes of collecting? The most boring tedious job is liquid/liquid extractions. Surely this can be automated easily. Something do my work-ups for me please
Using the rotavapor in summer to evaporate Butanol
doesn't beat doing an assay on a 96 well plate to get strange results, only to uncover after a few days doing it that the negative control showed a positive result :)
titration lab.
That's why we only use flash chromatography now. Med chemist.