How Do You Like Your Caffeine?
Inhaled or oral?
Natural or synthetic?
Two interesting reports came across the interwebs over the last couple of days.
Earlier this week, the US Food and Drug Administration issued a warning letter (press release) to makers of Aeroshot brand of inhaled caffeine. No, it's not an asthma medicine (although oral theophylline is). It's billed as a non-caloric caffeine delivery system, 100 mg per hit. That's roughly the amount in two 12 fl oz/355 mL cans of Mountain Dew or one gulp more than a 8.4 fl oz/250 mL can of Red Bull energy drink. However, the company claims that only 15-25 mg are delivered - perhaps half the amount in a Coca-Cola.
The FDA has concerns about the dual promotion of the product for swallowing and inhalation, the relative safety of inhaled caffeine, and the potential for children and adolescents to use the product in combination with alcohol. The company's FAQ specifically notes that the product is not marketed for use in children. Readers will recall that Four Loko caffeinated alcohol drinks were withdrawn from the market in late 2010 and replaced with alcohol-only versions.
On another front, Analytical Chemistry published a paper by a group led by Maik Jochmann at Essen, Germany on an isotopic ratio method for determining whether caffeine in a consumer product is derived from plants or synthetically. While public demand for naturally-caffeinated products doesn't seem to be especially a big deal in the US, the FDA only requires listing of caffeine content for products with added synthetic caffeine.
(Note: I only just found out this afternoon that C&EN Online had covered this paper back on February 29th. My apologies to all for not linking to it. That report is here.)
The authors show here that 13C ratios can indeed be used to determine the source of caffeine. In general, 13C represents 1.11% of Earth's carbon. However, plants incorporate less 13C in making caffeine via C3 carbon fixation from atmospheric carbon dioxide. I'm still a bit unclear as to whether the method can determine the difference between naturally-occurring caffeine from products spiked with purified, plant-derived caffeine (I don't think so).
From Zhang et al., doi:10.1021/ac203197d
In the paper, I learned something new and of relevance to the American South (where I live): the international standard for 13C/12C ratios is Vienna Pee Dee Belemnite (VPDB).
In 1957, the late Scripps Institution of Oceanography geochemist Harmon Craig, defined terrestrial carbon isotope ratios from a fossilized cephalopod in the Pee Dee limestone formation of South Carolina. Although none of the original specimen remains, secondary standards are now used for calculations.
To complete our history lesson, you should know that the Pee Dee River is named after Native Americans who once populated this river basin that runs from the North Carolina Piedmont into South Carolina.
Hopefully you don't need any extra caffeine after getting to the end of this post.
Behold Planet Earth's carbon isotope standard. Credit: Phil Tyden (click picture for source).