A Simple Experiment in the Separation of a Solid-Phase Mixture and Infrared Spectroscopy for Introductory Chemistry

This experiment was developed as a means of incorporating instrumental analyses into an introductory chemistry laboratory. A two-component solid mixture of caffeine and ibuprofen is separated through a series of solution extractions and precipitation and their relative amounts measured. These compounds were chosen because the combination of caffeine and ibuprofen as an oral suspension has recently been investigated for pain relieving capabilities superior to those of ibuprofen alone providing a real-world context to the experiment. The solid components once recovered, dried, and weighed are analyzed using infrared spectrophotometry (IR). The goal of the IR analysis is to determine how effectively the two components were separated by comparing their spectra with the known spectra of the pure components. A guided-inquiry approach is utilized throughout the procedure for this experiment.