Outtake Chapter One- “Headache”

My grades resulted from excelling in every science course I took, with one exception. I lost my perfect record to tainted aspirin. Biological Instrumentation was an upper-division class consisting of two lectures and a four-hour lab every week. The course exposed students to laboratory-based scientific equipment and techniques. The final exam for the lab portion followed a tricky recipe: precisely weighing pure chemical ingredients, mixing them to create chemical reactions under highly controlled conditions, followed by distillation in a sophisticated apparatus to synthesize acetylsalicylic acid, the primary component of aspirin. My grade rested on the purity of the final distillate: ten cc’s of clear, colorless, odorless liquid. Only six students were in this class, and when we all completed the distillation process, we moved on to the final step, using gas chromatography to assess the purity of individual end products.

            A gas chromatograph is a table top instrument in the shape of a large box that volatilizes (turns to gas) a sample of liquid injected through a port on the front. The machine separates different chemicals based on how fast or slow they transit through a long, coiled tube to a “detector” at the end of the coil. Each chemical has a different transit time based on the physical properties of its molecules. The detector sends a signal to a printer, which produces a graphic representation of the chemical as a spike or peak. In our exercise, a perfect score consisted of precisely two peaks registered on the printout. One peak was ether, which was used to clean the micro-syringe of any impurities before taking up the sample. Traces of the ether would remain in the syringe and be caught by the detector. The other peak was acetylsalicylic acid, the liquid gold of the exercise. Any other peaks would be impurities, which could enter the process anywhere along the line: a contaminant in the glassware, a beaker left uncovered, improper distillation, weighing and measuring errors, etc.

            We assembled in a line to inject our samples, using a freshly cleaned micro-syringe to place three microliters of sample into the port, a microliter being one-millionth of a liter. Each sample was processed in a matter of a few minutes. Dr. Chris Skreptos, the instructor, held court as we hovered around the printout console, chattering nervously and feigning nonchalance. It felt like a competition. In the end, no one got two clean peaks; I got four, meaning two impurities. The printout provided additional data; it calculated the area under each peak, representing its percentage of the entire sample.  My impurity peaks were small, but the bottom line was 84% acetylsalicylic acid and 16% impurities (including the ether), which converted to a “C” for the exercise, a “B” for the course, and an “H” for headache.