Articles by: Chemjobber

Meth mouth: not ‘toxins’, just good ol’ tooth decay

As a long-time fan of media critic Jack Shafer, I remember well his diatribes against the myth that ‘meth mouth’ (the tooth decay that afflicts long-time methamphetamine abusers) is caused by the chemistry of methamphetamine or any contaminants from the preparation. The causes (dry mouth and lack of dental care) has been discussed in the peer-reviewed literature.

So I was surprised to see it in the middle of a really interesting article on underground chemistry by Discover Magazine:

In attempting to synthesize crystal meth, these do-it-yourselfers have caused a rash of trailer park explosions and often unwittingly produce a drug coated with toxins like hydroiodic acid. The best way to remove those noxious byproducts is by washing the drug in alcohol using a Büchner funnel, a specialized lab vacuum. But most kitchen chemists have never even heard of it. When this final purification step is skipped, the toxins eat away at the user’s gums, teeth, and inner lining of the cheeks, resulting in a toothless, hollowed-out condition known as “meth mouth.”

No, no, no. What causes ‘meth mouth’? Is it toxins? Is it uneluted hydroiodic acid? Well, let’s look at the American Dental Association page that it links:

The extensive tooth decay is probably caused by a combination of drug-induced psychological and physiological changes resulting in dry mouth and long periods of poor oral hygiene. A methamphetamine “high” lasts much longer than that produced by crack cocaine (12 hours versus one hour for cocaine). This can lead to long periods of poor oral hygiene. And while they are high, users often crave high-calorie, carbonated, sugary beverages or they may grind or clench their teeth, all of which can harm teeth.

So, there we have it. There’s no reason to blame hydroiodic acid (or the solvents, or “toxins” or acids in the process) when it comes to ‘meth mouth’; it’s just advanced tooth decay.

By May 26, 2012 2 comments science news, Uncategorized

What is that thing? The new GHS symbol for carcinogens

What's happening to that guy?!?

The Globally Harmonized System of Classification and Labeling of Chemicals (GHS) is the new international standard for shipping and labeling chemicals so that their hazards are communicated in a logical fashion. Since we’re now in a globalized commerce system, where (for example) Aldrich sells chemicals all over the world , GHS creates a single standard for how different hazards (physical, health, environmental) will be communicated to shippers and receivers.

So if you look at the new symbols, they’re all pretty boring. I feel like the skull on the “toxic” label is just a little bit different and the dead fish for the “environmental hazard” is a little graphic, but gets the point across well.

But here’s my question — what’s this label on the right supposed to communicate? Any guesses?

That is the new GHS symbol for carcinogenicity. While I understand that you can’t write “HEY, DUMMY! THIS WILL GIVE YOU CANCER” in fifteen different languages, I feel that this thing that looks like the T-1000 after being hit with a shotgun will just lead to confusion in all parts of the world.

I shouldn’t criticize and not offer a better solution, but I’m not positive that there is one. It’s such a difficult concept to attempt to communicate. The broken double helix motif of the cancer hazard sign is aesthetically pleasing and logical, but it requires an understanding of basic molecular biology that Starman this symbol doesn’t require.

By April 7, 2012 24 comments chemical safety

Ice is not just ice

I'd go for the one on the left.

Dozois' "ice rock" on the left, typical ice on the right (Photo credit: Katie Robbins, for The Atlantic)

Gourmet ice? Yeah, it’s not really my thing either (I’m not much of a drinker, and when I do, it’s mostly microbrew.) But I found the story of entrepreneur Michel Dozois on the The Atlantic’s website to be pretty interesting and something that I find just tiny little bit terrifying as a chemist:

Although he was using recipes he’d made many times before, in this new setting, suddenly none were quite right. “My cocktails sucked. I’m pissed,” he recalls. “The ingredients were almost the same. The recipes, I know, I had them. They were great. That’s the moment where you’re like dude, what am I doing wrong? And you’re flipping out.”

It wasn’t until he took a sip from one of the rejected cocktail glasses, by then just a pool of melted ice, that he realized the source of the foul taste. “l looked down at that and I realized, it’s f–king sh–ty ice. That’s what that is. The ice is f–king up all of my cocktails. Every one of them.”

Now there’s something I haven’t been thinking about as a chemist, which is the contents of the ice that I’m throwing into reactions for cooling, dilution or precipitation. Dozois has begun selling gourmet ice to high-end bars in L.A. with different shapes. Some of Dozois’ ice (like the pictured “ice rock” above, left) allows for cooler drinks without as much dilution. His preparation is quite involved:

Dozois says the key lies in three principles—filtration, aging, and shape. The water is filtered twice, using reverse osmosis, through which he says the company loses about eight ounces of water for every one ounce preserved. Once purified, the water is then frozen, where it is aged for at least 48 hours, increasing its density and making it colder and stronger. Though other ice connoisseurs don’t age their frozen cubes, Dozois considers this step so integral to his product that he took the name Névé, the word for compacted snow that ultimately becomes glacial ice.

The ice is then cut into one of four different products. “Every cocktail calls for different dilution, different ice, different needs,” Dozois explains. In addition to the Old Fashioned cubes, Névé also makes sells a longer, narrower Tom Collins cube made for high ball glasses, and a sexy orb-shaped version, modeled after Japanese ice spheres. Of all the products, Dozois has a special fondness for the “shaking ice,” a small cornerless cube, which because of ageing and its unique design can withstand a vigorous joggle in a cocktail shaker without breaking.

While this doesn’t deal with reaction chemistry directly, I am reminded of the different uses of ice for precipitating compounds from solution. Certainly, you wouldn’t want one big block of ice (less surface area); you’d probably want a smaller, more pellet-like ice for the best precipitating results (and possibly, the best cooling of reactions.) Interesting how the same principles guide mixologists and chemists to different choices.

By February 13, 2011 7 comments fun, physical chemistry, Uncategorized

Separating the lanthanides: physical versus chemical methods?

How do you separate dirt?

Photo credit: Reuters**

There has been much talk about rare earth metals recently. In short, the People’s Republic of China has become the dominant source of rare earth* elements in the world; the PRC government has used that fact to their strategic advantage. I don’t really wish to get into the political debate; suffice it to say that I think there’s more smoke than fire here and that predictions of war are probably overblown.

There are quite a number of articles on the subject, but only one talked about the chemistry. I was struck by a quote in an article on by Tim Worstall, a trader in scandium and other rare earths (now there’s a job I didn’t know about):

Another possibility is that we find a new and different way to separate rare earths, as we find new and different sources for the ores. The main difficulty is that chemistry is all about the electrons in the outer ring around an atom, and the lanthanides all have the same number of electrons in that outer ring. Thus we can’t use chemistry to separate them. It’s very like the uranium business: Separating the stuff that explodes from the stuff that doesn’t is the difficult and expensive part of building an atomic bomb precisely because we cannot use chemistry to do it — we have to use physics.

It’s quite apparent that Mr. Worstall is referring to the unusual electronic configuration of the lanthanides, where the 4f orbitals are ‘hidden’ behind the 4d and 5d orbitals. This electronic configuration is also responsible for the lanthanide contraction, in which the atomic radii of the lanthanides are smaller than predictable by periodic trends.

However, I’m not quite sure what Mr. Worstall means when he draws a distinction between chemical and physical separation of the elements. Both this article (from Oxford) and the Wikipedia article on the lanthanides suggest that countercurrent exchange methods are used on industrial scale; it appears that separation is performed by means of ionic radii and size. While this certainly doesn’t rely on the reaction chemistry of the lanthanides (because it appears they all act similar), I have a difficult time calling these techniques physics-based.

Readers, can you shed any more light on the issue? Do you agree with Mr. Worstall’s distinction between chemical and physical means of purifying elements?

*It should be noted that the rare earths are, as they say, neither rare or nor earths.
**Photo from this International Business Times article.