Seems the initial reporting may have been misleading. There was apparently *no* dimethylmercury exposure, after all: and MIT doubts it was synthesized in the first place.
She had very high levels of mercury in her blood, and all attempts at chelation therapy to remove it were ineffective. That’s surely because it had spread throughout her body by the time the problem was recognized, but frankly no one can be sure if there were any measures that could have been effective enough after the initial exposure.
Is this accurate? I read the original Wetterhahn report (it's the first search result on Google) and chelation did appear to reduce whole blood mercury, but didn't do anything for the CNS exposure.
That would be important because it suggests immediate Succimer treatment could avert fatal CNS exposure (it takes hours/days for the blood/brain transfer to occur, apparently).
There are also some studies suggesting that the amount of excess mercury in fish compared to selenium may be more relevant than the absolute mercury concentration in causing potential toxicity.
Oh thank goodness. I was honestly shaken just thinking about how horrifying it would be to be a college-aged student who managed to expose themselves to dimethylmercury. Even if they were doing something stupid and reckless, that's a horrible way to go.
Note that it seems increasingly unlikely that it was actually synthesized.
> Emerging information calls into question whether this compound was in fact synthesized.
> while the student remains under medical supervision, their initial blood test result, which was received today, shows no sign of exposure to mercury.
Imagine thinking you'd killed yourself, and then breathing the intense sigh of relief when you realize you're bad at chemistry and you didn't manage to synthesize the compound correctly.
Other "sources" (using the word loosely as their provenance is unclear)
> "based on the information available, this was a localized issue with only one student directly exposed. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury." [1]
Karen Wetterhahn's exposure and death [3] is a cautionary tale of the extreme toxicity of dimethyl mercury, and was instrumental in new safety recommendations, including strongly discouraging the use of dimethyl mercury for any purpose.
Yes, dimethyl mercury is terrifying stuff - it killed Karen Wetterhahn from a few drops that went _through_ the gloves she had on:
> The case proved that the standard precautions at the time, all of which Wetterhahn had carefully followed, were inadequate for "super-toxic" chemicals like dimethylmercury
There was a time not so long ago when it was common for chemistry teachers to show off pools of mercury in their bare hands.
By the time I first took chemistry classes, though, that practice had stopped, less out of concern of exposure to liquid mercury and more for accidental exposure to gaseous forms due to spills.
Back in 1998, I scored a consulting job at a silicon plant outside of Salem, OR. Now I was working as a systems admin and I was expected to be responsible for the computer systems, which were basically located in the normal offices, rather than a dedicated machine room floor.
However, since it was an active silicon manufacturing plant, all employees and contractors were obligated to complete safety training sessions. And I swear now that these safety sessions were designed to weed out the faint-hearted guys who weren't serious about supporting this silicon brand.
The safety sessions were simple lectures, with some handouts and PowerPoints, and some of the chemicals they described were absolutely insidious stuff. They were colorless, odorless, and some could melt or disintegrate bone without noticeably affecting the skin or muscles. They said you would just end up with a limp and useless appendage if you spilled some of this stuff on you. Other stuff was highly toxic and you didn't want to breathe anything. Basically it was a big warning to just stay out of the manufacturing floor, especially if we didn't know what we were doing.
I never went near the manufacturing floor. It was a pretty cool job and I wish I lasted longer there. They couldn't scare me away with a safety session, since my Dad had worked for decades in Environmental Health and Safety. Dad knew all about the nastiest stuff and he was always responding to hazardous laboratory accidents. Dad made us the safest home in our ZIP code.
I think Hydrofluoric acid is probably the substance you're describing which leaches the calcium out of your bones. It will certainly burn you too though. It's a common byproduct from heating fluorinated gases and is sometimes used in its own right for wet etching.
As an aside, I love it when they tell you in the safety WBT what the highly toxic gas smells like.
Rechargeable lithium batteries pose a higher risk than single-use lithium batteries. Only the rechargeable ones have a thermal runaway hazard. I figured it was wise to get rid of old rechargeable lithium batteries that I no longer need or use.
Fwiw, there is a BurnBuster brand of fire extinguisher for stopping lithium runaway. See ASIN B0DZ9R7Q51. It is a ripoff but probably good to have.
Single use ones too can contain fluorine, but not the runaway risk. Nevertheless, they require significant care to avoid shorting during storage. Never store them loose or where they can contact each other. Tape them well from all sides, and put them in a sealed ziploc bag before disposing.
For lower concentrations (< 50%) HF burns aren't always immediately visible (and often not immediately painful), which can delay treatment as people may assume it's not serious.
Reminds me of something from chemistry class but I can"t remember exactly what it was (this was several decades ago now), I think it was sometimes used for etching glass, but if it got into your body -- I'm not sure if getting it just on your skin was necessarily a lethal hazard -- it would leech the calcium from your bones and was considered an especially nasty way to go. Our prof was helping her father in law clean out his garage and he had a bunch of it in a container, bought in the 60's or 70's for a glass etching kit, and was like "Okay I'm getting rid of this, but have you got any other hobbies you've been meaning to get around to that I should know about?".
His "Things I Won't Work With" series on Science (https://www.science.org/topic/blog-category/things-i-wont-wo...) is fun to read. The link in the article itself now unfortunately just points to the science.org homepage so you have to do some clicking around to get to this blog series.
> One problem with this subject is that it tends to lead to bragging contests about who has run the most hazardous reactions. But think about it: if these reactions have all been run for good reasons with the best protective equipment there is less to brag about. And if they haven’t, then the discussion turns into figuring out who has been the biggest fool
I suspect the answer is "bragging rights" in this case.
Sadly old.reddit.com has started requiring a login now. It worked for me up until today. Another site off the reading list, unless someone knows a workaround (I tried deleting cookies).
> "A message sent out from the chair of the department of chemistry at the school identifying the substance in question:"
> "“Dear Chemistry Colleagues,"
> "I am writing to provide an update on efforts to reopen Building 18 safely."
> "A specialized team from Triumvirate Environmental worked overnight on decontamination efforts in the building. This work includes wipe-downs of relevant surfaces in the lab and common areas, as well as the safe disposal of items that may have been contaminated. Decontamination work will continue throughout the day, and the building will remain closed until the work is complete."
> "In addition to our health and safety experts, we have been working continuously with staff and colleagues from departments across the Institute. Our highest priority is community safety, and we continue to make decisions accordingly and gather as much information as we can."
> "It remains the case that, based on the information available, this was a localized issue with only one student directly exposed, and this student was the individual working with the compound. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury."
> "I want to reiterate that, based on the information available to me, our industrial hygienists, MIT Health medical experts, and other resources we've consulted, the risk of secondary or tertiary exposures remains low, given the compound's characteristics and the information available to us."
> "Please feel free to reach out with questions. I will continue to provide regular updates as we learn and have more to share."
Can someone who knows a thing or two about chemistry explain why one would need to synthesize or purchase this chemical. Given that it involves a student I'll take "because of bragging rights to impress everyone" as a valid response, but wondering if it has any value is otherwise? Is it one of those "well despite its danger it's still the best at X, Y and Z and nothing else comes even close"?
I forget the guy's name, but he writes entertaining articles about chemistry things he'll never mess with. I wonder if Dimethyl Mercury is one of them.
Edit: reading further down the comments, Derek Lowe is guy.
Wow, I wonder if chelation therapy early enough can reduce the damage to the student's nervous system. I'm not aware of how quickly organic mercury crosses the BBB once it enters the bloodstream, but my guess is "faster than you'd like".
I hope it was worth working with such a notoriously unsafe compound against regulations and all sense.
Yeah that was awful, but in her case she was unaware of the poisoning for months iirc. Then again I don't really buy that chelation therapy works that well for something as absurdly toxic as this even if you found a safe and workable ligand.
I guess the student just needs to hope their exposure was incredibly minute, otherwise they really have only a hard death to look forward to.
There are some new results for treatment with selenium and acetyl cysteine. MGH is probably the best place to get treatment for this. We’ll have to wait and see, and there is not any information out about the extent of exposure. Prior cases all seem to have only sought treatment upon getting symptoms, so I am cautiously optimistic about this case
Why were they working with an unauthorised potent neurotoxin? MIT didn't "permit" this, although you could ask how student supervision allows it to arise.
Is there some interesting aspect which danger aside might motivate this or was it just a dick move? Were they possibly motivated for bad reasons, seeking to commit harm?
Dimethylmercury is (or was, at least historically) used as a reference material for nuclear magnetic resonance (a common analytical method used in chemistry):
This MIT incident was in a chemistry building that has been in use since 1970, so it could have been accidental release of an old, unused container or sample tube of the material.
The synthesis attempt was not for this. It's unclear what they were attempting and it's impossible that they didn't know the stakes. Their lab develops fundamental organic methods.
Thanks! 40+ years ago I worked in a marine biology lab as a dishpig for seawater analysis and we had fun times when the annual clear out found a gallon jug of benzene at the point of panic about benzene being replaced by toluene.
If the lab is going to check for trace benzene in the water, ideally you would have some pure material for reference purposes.
Put that in perspective against industrial quantities where a hardhat operator opens the hatch on a very full compartment of a chemical tanker, looking at their mirror image reflecting up from the surface of a few hundred tonnes of cargo a few feet below.
Which is then carefully sampled and delivered to a lab where they check for trace water in the benzene.
"Emerging information calls into question whether this compound was in fact synthesized. We are also able to disclose, with the student’s permission, that while the student remains under medical supervision, their initial blood test result, which was received today, shows no sign of exposure to mercury."
Dimethylmercury evaporates to a known degree. Way way more than elemental mercury.
To detect elemental mercury vapor, the air is drawn in to a controlled chamber where if present it amalgamates with pure gold as the reference (zero) material, and determined electronically.
I don't think this works with organic mercury like dimethylmercury. It is an organo-metallic compound and behaves very unlike elemental mercury.
I'd be running the AA's from the analytical labs in mercury-vapor mode, putting them on carts if necessary since they do not need gas supplies for mercury detection & measurement.
Before plasma-emission spectrometers became widespread, more people were familiar with the traditional atomic-absorption (AA) instruments.
Instead of measuring the combined emission of any elements present in the sample, the AA used the steady emission of the target element alone as reference, from a (expensive) lamp having that specific element present within its hollow cathode.
AA normally uses a clean acetylene flame to vaporize the sample, with the reference light beam passing above the flame. If the target element is present in the sample, it absorbs some of the characteristic wavelength from the beam and is detected as a negative deviation from baseline.
For trace mercury though, the flame was not good enough, so an even more expensive and complex graphite furnace was installed in place of the burner.
Either way the light beam passes through a few inches of lab air to get from the lamp to the optical detector.
And you don't need the burner or the furnace to detect things that are already vaporized.
The graphite furnace would be good to calibrate with later if you couldn't do it in advance.
I wonder if their contractor has as good detection ability as MIT itself.
Out of curiosity, does this reset/modify the timestamps of the old posts? I was confused at reading comments from "hours ago" I thought for sure I'd read days ago.
Sorry for the confusion—I know it's weird but the alternative turns out to be even more confusing and we've never figured out how to square that circle!
Derek Lowe has comments about this incident,
https://www.science.org/content/blog-post/alleged-dimethylme... ("The Alleged Dimethylmercury Incident")
Seems the initial reporting may have been misleading. There was apparently *no* dimethylmercury exposure, after all: and MIT doubts it was synthesized in the first place.
She had very high levels of mercury in her blood, and all attempts at chelation therapy to remove it were ineffective. That’s surely because it had spread throughout her body by the time the problem was recognized, but frankly no one can be sure if there were any measures that could have been effective enough after the initial exposure.
Is this accurate? I read the original Wetterhahn report (it's the first search result on Google) and chelation did appear to reduce whole blood mercury, but didn't do anything for the CNS exposure.
That would be important because it suggests immediate Succimer treatment could avert fatal CNS exposure (it takes hours/days for the blood/brain transfer to occur, apparently).
Obviously, not an expert.
Here’s an interesting article suggesting that selenium and acetylcysteine may be superior to succimer:
https://www.tandfonline.com/doi/full/10.1080/24734306.2020.1...
There are also some studies suggesting that the amount of excess mercury in fish compared to selenium may be more relevant than the absolute mercury concentration in causing potential toxicity.
I think the article meant "ineffective" as in "it didn't save her life", not "it didn't do anything".
Oh thank goodness. I was honestly shaken just thinking about how horrifying it would be to be a college-aged student who managed to expose themselves to dimethylmercury. Even if they were doing something stupid and reckless, that's a horrible way to go.
Note that it seems increasingly unlikely that it was actually synthesized.
> Emerging information calls into question whether this compound was in fact synthesized.
> while the student remains under medical supervision, their initial blood test result, which was received today, shows no sign of exposure to mercury.
Taken from https://emergency.mit.edu/
Imagine thinking you'd killed yourself, and then breathing the intense sigh of relief when you realize you're bad at chemistry and you didn't manage to synthesize the compound correctly.
The student could have just made it all up for some reason too.
Other "sources" (using the word loosely as their provenance is unclear)
Karen Wetterhahn's exposure and death [3] is a cautionary tale of the extreme toxicity of dimethyl mercury, and was instrumental in new safety recommendations, including strongly discouraging the use of dimethyl mercury for any purpose.[1] https://www.reddit.com/r/mit/comments/1w12gb9/dimethyl_mercu...
[2] https://www.nbcboston.com/news/local/hazmat-crews-respond-to...
[3] https://en.wikipedia.org/wiki/Karen_Wetterhahn
Yes, dimethyl mercury is terrifying stuff - it killed Karen Wetterhahn from a few drops that went _through_ the gloves she had on:
> The case proved that the standard precautions at the time, all of which Wetterhahn had carefully followed, were inadequate for "super-toxic" chemicals like dimethylmercury
(from the Wikipedia page [3])
> Less than 0.1 mL is capable of inducing severe mercury poisoning resulting in death
Holy hell. I would've have believed it was possible for a non-biological substance to be so toxic.
The density of Dimethyl Mercury is almost 3g/ml, so 0.1 mL is like 300 mg.
From https://en.wikipedia.org/wiki/Cyanide_poisoning
> A fatal dose for humans is on average 1.52 mg/kg of body weight
Assuming 80kg(175pounds), that's like 120mg of Cyanide.
There is probably even more nasty stuff.
well, easily. any organophosphorus stuff for example.
If you're worried about >100mg (0.1ml) then, don't think about the dosages people use for botox! It's 1x,2x,3x 80picograms per injection.
I guess it's a biological product, but it's certainly not "living".
Then there's carfentanil and similar which are deadly only at much higher 100 microgram levels.
the methyl groups make it organic chemistry (and dangerous), elemental mercury is fairly safe
There was a time not so long ago when it was common for chemistry teachers to show off pools of mercury in their bare hands.
By the time I first took chemistry classes, though, that practice had stopped, less out of concern of exposure to liquid mercury and more for accidental exposure to gaseous forms due to spills.
Good video about what happened to her body: https://www.youtube.com/watch?v=NJ7M01jV058
Back in 1998, I scored a consulting job at a silicon plant outside of Salem, OR. Now I was working as a systems admin and I was expected to be responsible for the computer systems, which were basically located in the normal offices, rather than a dedicated machine room floor.
However, since it was an active silicon manufacturing plant, all employees and contractors were obligated to complete safety training sessions. And I swear now that these safety sessions were designed to weed out the faint-hearted guys who weren't serious about supporting this silicon brand.
The safety sessions were simple lectures, with some handouts and PowerPoints, and some of the chemicals they described were absolutely insidious stuff. They were colorless, odorless, and some could melt or disintegrate bone without noticeably affecting the skin or muscles. They said you would just end up with a limp and useless appendage if you spilled some of this stuff on you. Other stuff was highly toxic and you didn't want to breathe anything. Basically it was a big warning to just stay out of the manufacturing floor, especially if we didn't know what we were doing.
I never went near the manufacturing floor. It was a pretty cool job and I wish I lasted longer there. They couldn't scare me away with a safety session, since my Dad had worked for decades in Environmental Health and Safety. Dad knew all about the nastiest stuff and he was always responding to hazardous laboratory accidents. Dad made us the safest home in our ZIP code.
I think Hydrofluoric acid is probably the substance you're describing which leaches the calcium out of your bones. It will certainly burn you too though. It's a common byproduct from heating fluorinated gases and is sometimes used in its own right for wet etching.
As an aside, I love it when they tell you in the safety WBT what the highly toxic gas smells like.
HF is released in lithium ion battery fires. Just one reason why the correct response to such a fire is GTFO as fast as you can.
Reading through https://www.mass.gov/doc/toxicology-of-the-lithium-ion-batte..., especially seeing the skin impact of a battery combustion in someone's pocket, is enough to make me think I should keep an inventory of every Li-ion battery in the house.
Rechargeable lithium batteries pose a higher risk than single-use lithium batteries. Only the rechargeable ones have a thermal runaway hazard. I figured it was wise to get rid of old rechargeable lithium batteries that I no longer need or use.
Fwiw, there is a BurnBuster brand of fire extinguisher for stopping lithium runaway. See ASIN B0DZ9R7Q51. It is a ripoff but probably good to have.
Single use ones too can contain fluorine, but not the runaway risk. Nevertheless, they require significant care to avoid shorting during storage. Never store them loose or where they can contact each other. Tape them well from all sides, and put them in a sealed ziploc bag before disposing.
For lower concentrations (< 50%) HF burns aren't always immediately visible (and often not immediately painful), which can delay treatment as people may assume it's not serious.
Yes it can destroy your nerves faster than you register pain, so you might not even feel the damage HF caused
Reminds me of something from chemistry class but I can"t remember exactly what it was (this was several decades ago now), I think it was sometimes used for etching glass, but if it got into your body -- I'm not sure if getting it just on your skin was necessarily a lethal hazard -- it would leech the calcium from your bones and was considered an especially nasty way to go. Our prof was helping her father in law clean out his garage and he had a bunch of it in a container, bought in the 60's or 70's for a glass etching kit, and was like "Okay I'm getting rid of this, but have you got any other hobbies you've been meaning to get around to that I should know about?".
Sorry I believe it was copper etching maybe, probably not glass. Been a while...
Oh yeah, cleaning chemical vapor deposition chambers in semiconductor industry, that's another one from Derek Lowe: https://www.science.org/content/blog-post/sand-won-t-save-yo...
Silicon fabs are definitely up there for 'regular use of scary chemicals'.
Derek Lowe mentions dimethyl mercury as the first substance that's not worth the risk:
https://www.chemistryworld.com/opinion/a-risk-not-worth-taki...
His "Things I Won't Work With" series on Science (https://www.science.org/topic/blog-category/things-i-wont-wo...) is fun to read. The link in the article itself now unfortunately just points to the science.org homepage so you have to do some clicking around to get to this blog series.
From the link:
> One problem with this subject is that it tends to lead to bragging contests about who has run the most hazardous reactions. But think about it: if these reactions have all been run for good reasons with the best protective equipment there is less to brag about. And if they haven’t, then the discussion turns into figuring out who has been the biggest fool
I suspect the answer is "bragging rights" in this case.
This was my first thought.-
(Well, the poor woman, then, this article ...)
some will be unfriendly or hostile towards the safety-conservative.
Usually the managers of the people that could be affected.
Mods censoring the post for being trolling "disrespectful to the community" is classic Reddit.
Some guy's in the hospital from handling droplets of instant liquid death and they're worried about feelings being hurt?
Apparently the article was, in fact, trolling with inaccurate speculative 'information.'
The deleted post was a "Dear Colleagues" letter written by an MIT chemistry faculty member. It's the same letter posted here:
https://old.reddit.com/r/labrats/comments/1w1ukrv/mit_studen... ("A message sent out from the chair of the department of chemistry...")
Sadly old.reddit.com has started requiring a login now. It worked for me up until today. Another site off the reading list, unless someone knows a workaround (I tried deleting cookies).
Ahh, that was thoughtless of me!
> "A message sent out from the chair of the department of chemistry at the school identifying the substance in question:"
> "“Dear Chemistry Colleagues,"
> "I am writing to provide an update on efforts to reopen Building 18 safely."
> "A specialized team from Triumvirate Environmental worked overnight on decontamination efforts in the building. This work includes wipe-downs of relevant surfaces in the lab and common areas, as well as the safe disposal of items that may have been contaminated. Decontamination work will continue throughout the day, and the building will remain closed until the work is complete."
> "In addition to our health and safety experts, we have been working continuously with staff and colleagues from departments across the Institute. Our highest priority is community safety, and we continue to make decisions accordingly and gather as much information as we can."
> "It remains the case that, based on the information available, this was a localized issue with only one student directly exposed, and this student was the individual working with the compound. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury."
> "I want to reiterate that, based on the information available to me, our industrial hygienists, MIT Health medical experts, and other resources we've consulted, the risk of secondary or tertiary exposures remains low, given the compound's characteristics and the information available to us."
> "Please feel free to reach out with questions. I will continue to provide regular updates as we learn and have more to share."
> "With care and regards,"
> "Matt Shoulders”"
>Log in to use old Reddit
>To keep Reddit safe, accounts are required to access old Reddit.
God, I hate that horrible website. How does this keep people "safe"
Legend has it that shareholders are people. None can prove it though.
Can someone who knows a thing or two about chemistry explain why one would need to synthesize or purchase this chemical. Given that it involves a student I'll take "because of bragging rights to impress everyone" as a valid response, but wondering if it has any value is otherwise? Is it one of those "well despite its danger it's still the best at X, Y and Z and nothing else comes even close"?
It can theoretically be used as rocket fuel.
I forget the guy's name, but he writes entertaining articles about chemistry things he'll never mess with. I wonder if Dimethyl Mercury is one of them.
Edit: reading further down the comments, Derek Lowe is guy.
It is: https://news.ycombinator.com/item?id=49488014
Wow, I wonder if chelation therapy early enough can reduce the damage to the student's nervous system. I'm not aware of how quickly organic mercury crosses the BBB once it enters the bloodstream, but my guess is "faster than you'd like".
I hope it was worth working with such a notoriously unsafe compound against regulations and all sense.
If you look at the reddit thread, there is a horrific story:
https://en.wikipedia.org/wiki/Karen_Wetterhahn#Accident_and_...
Yeah that was awful, but in her case she was unaware of the poisoning for months iirc. Then again I don't really buy that chelation therapy works that well for something as absurdly toxic as this even if you found a safe and workable ligand.
I guess the student just needs to hope their exposure was incredibly minute, otherwise they really have only a hard death to look forward to.
There are some new results for treatment with selenium and acetyl cysteine. MGH is probably the best place to get treatment for this. We’ll have to wait and see, and there is not any information out about the extent of exposure. Prior cases all seem to have only sought treatment upon getting symptoms, so I am cautiously optimistic about this case
Why were they working with an unauthorised potent neurotoxin? MIT didn't "permit" this, although you could ask how student supervision allows it to arise.
Is there some interesting aspect which danger aside might motivate this or was it just a dick move? Were they possibly motivated for bad reasons, seeking to commit harm?
Dimethylmercury is (or was, at least historically) used as a reference material for nuclear magnetic resonance (a common analytical method used in chemistry):
https://sites.northwestern.edu/ohalloran/199hg-nmr-standards...
This MIT incident was in a chemistry building that has been in use since 1970, so it could have been accidental release of an old, unused container or sample tube of the material.
The synthesis attempt was not for this. It's unclear what they were attempting and it's impossible that they didn't know the stakes. Their lab develops fundamental organic methods.
Thanks! 40+ years ago I worked in a marine biology lab as a dishpig for seawater analysis and we had fun times when the annual clear out found a gallon jug of benzene at the point of panic about benzene being replaced by toluene.
If the lab is going to check for trace benzene in the water, ideally you would have some pure material for reference purposes.
Put that in perspective against industrial quantities where a hardhat operator opens the hatch on a very full compartment of a chemical tanker, looking at their mirror image reflecting up from the surface of a few hundred tonnes of cargo a few feet below.
Which is then carefully sampled and delivered to a lab where they check for trace water in the benzene.
The wording of the announcements, sounds like a student synthesized it. Can't imagine why, hopefully it wasn't a fatal mistake.
There's also an alert on the MIT emergency page, though it doesn't mention the substance by name: https://emergency.mit.net/
Latest update reads in part:
"Emerging information calls into question whether this compound was in fact synthesized. We are also able to disclose, with the student’s permission, that while the student remains under medical supervision, their initial blood test result, which was received today, shows no sign of exposure to mercury."
Dimethylmercury evaporates to a known degree. Way way more than elemental mercury.
To detect elemental mercury vapor, the air is drawn in to a controlled chamber where if present it amalgamates with pure gold as the reference (zero) material, and determined electronically.
I don't think this works with organic mercury like dimethylmercury. It is an organo-metallic compound and behaves very unlike elemental mercury.
I'd be running the AA's from the analytical labs in mercury-vapor mode, putting them on carts if necessary since they do not need gas supplies for mercury detection & measurement.
Before plasma-emission spectrometers became widespread, more people were familiar with the traditional atomic-absorption (AA) instruments.
Instead of measuring the combined emission of any elements present in the sample, the AA used the steady emission of the target element alone as reference, from a (expensive) lamp having that specific element present within its hollow cathode.
AA normally uses a clean acetylene flame to vaporize the sample, with the reference light beam passing above the flame. If the target element is present in the sample, it absorbs some of the characteristic wavelength from the beam and is detected as a negative deviation from baseline.
For trace mercury though, the flame was not good enough, so an even more expensive and complex graphite furnace was installed in place of the burner.
Either way the light beam passes through a few inches of lab air to get from the lamp to the optical detector.
And you don't need the burner or the furnace to detect things that are already vaporized.
The graphite furnace would be good to calibrate with later if you couldn't do it in advance.
I wonder if their contractor has as good detection ability as MIT itself.
https://xprivate.lol/andrew_n_carr/status/209352439039069423...
Related thread: https://news.ycombinator.com/item?id=49484912
(since merged hither)
Out of curiosity, does this reset/modify the timestamps of the old posts? I was confused at reading comments from "hours ago" I thought for sure I'd read days ago.
Yes. The re-upping system is described at https://news.ycombinator.com/item?id=26998308 and links back from there. About the timestamps, there are past explanations here: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que.... I hope that will make sense.
Sorry for the confusion—I know it's weird but the alternative turns out to be even more confusing and we've never figured out how to square that circle!