The most important duty of the chemistry interns is FDA testing (yes, the Food and Drug Administration FDA), and I began performing this process for the first time this week. It will be a major responsibility for us interns for the entire summer. This testing is performed on all food-grade materials that we produce and is used to detect the presence of aromatic compounds, which can commonly be toxic and/or carcinogenic. Part of the refining process is meant to take out these impurities, and the FDA tests make sure that this properly occurred. Any remaining aromatics are extracted from a wax or petrolatum sample using a series of washes, including multiple rounds of DMSO/phosphoric acid, isooctane, and water in separate processes. In the end, we result in a 25 mL sample of isooctane that contains any remaining products that would be harmful to human health, and run a UVA spectroscopy on the sample using pure isooctane as the blank. These spectra are compared and given an allowed threshold of difference to decide whether or not the material passes the test. If there is too much difference in the spectra, we know that the material is unsafe for consumption. These tests are passed close to 100% of the time, as the refining process seldom makes major mistakes.
Typically, an FDA test will take a majority of the work day, as it involves a lot of long steps and clean up, as well as taking out the solvent waste and refilling the many materials used in the process (such as isopropanol, isooctane, etc.).