|Caffeine; aka Tree-of-life.|
Recently our chemistry department held a research symposium. A series of morning talks, lunch, and afternoon talks. Each series of lectures was punctuated by a brief coffee/stretch break, in which a hundred or so zombified chemists lined up single-file to the lone coffee dispenser. With a simple push of a button, each of us received, like holy communion, our ration of liquid alertness.
The cups were tiny, but the coffee soon ran dry. The caterer had not, for some reason, adequately estimated our caffeine needs, and thus disgruntled students and postdocs pressed and re-pressed the dispenser button with forlorn faces.
Our organic area chair was not pleased. With the assistance of some choice vocabulary, he expressed wonderment at the incompetence of the caterer.
"There's still some decaf," I pointed out. "We could just drink a couple thousand cups of that." (The decaf had not been touched, being functionally useless).
He chuckled. "There is some caffeine left over in decaffeinated coffee." Then an aside: "You know how they remove it? They market it as nature's effervescence.* But there's nothing natural about supercritical carbon dioxide."
For various reasons, typically health-related, there is a demand for decaffeinated coffee. The first industrial decaffeination processes used benzene (yikes). This method has fallen out of favor; the current most popular methods include ethyl acetate extraction, dichloromethane extraction (hello), water/charcoal, or supercritical carbon dioxide.
Amusingly, ethyl acetate extraction is referred to as "natural". In fact, a lot of coffee sources like to tout their "natural" methods. The popular Swiss Water Process, for example, is touted as "100% chemical-free" by many coffee dealers (despite rumors that the company employs a solution of aqueous dihydrogen monoxide). Caribou Coffee subscribes to this line of chemophobic nonsense.
Although it's tea and not coffee, Numi offers an amusing and confusing account of their "organic decaffeination process":
We use an organic CO2 process to decaffeinate our teas called "Effervescence." The tea is placed in a pressurized chamber and Carbon Dioxide, an inert gas, is pumped in and locks onto the leaves, extracting caffeine from tea leaves. This process does not leave any chemical residues and maintains antioxidant levels and flavor quality (in other processes, polyphenols are removed). This is the only chemical-free decaffeination method that does not extract flavor or health properties.Apparently carbon dioxide isn't a chemical. And it's inert (haha, joke's on you, everyone who's made carboxylates from organolithiums and dry ice!)? And they don't mention that the carbon dioxide is a supercritical fluid and not a gas, pressurized at several hundred atmospheres. But that would sound too much like a chemical, and chemicals are bad.
Altogether, "decaffeinated" is a bit of a misnomer. It's not caffeine-free. It's caffeine-deficient. Some caffeine still remains (this should come as no surprise).
A normal (i.e. useful) cup of coffee contains about 110 mg of caffeine (or more, or less, depending on brew method and whatever source you're looking at). Decaf contains up to around 10 mg (or as little as 2 mg; it depends, I guess). So via some quick computational methods we can say that there are 11 cups of decaf to one cup of real coffee (or 55 cups if you have 2 mg in a cup). Call it ten for sig figs' sake. That's about as good as you'll get.
So don't worry. Chug anywhere from ten to fifty-five cups of decaf when your departmental seminar runs out of regular and you'll be good to go. But since that's 1.9 to 10.3 quarts (1.8 to 9.8 liters) of liquid (a common guideline is a max tolerance of about 1 liter of water per hour max), you may just have to sleep through that materials chemistry seminar.
* This may occasionally also refer to the use of 'sparkling water', which is not natural, either.