Isolation and Gas Chromatographic Analysis of Dextromethorphan from Cough Syrup

In the previous laboratory experiment, we saw how the intermolecular forces between molecules determined the boiling point of a liquid. Distillation was one method which could be used to separate (or purify) chemical compounds. Unfortunately, distillation is not always a practical method to employ for purifications. Large molecules can have extremely high boiling points, even under reduced pressure. Many times, the heat required for a distillation will cause the compound to decompose. A milder method of purifying chemicals involves exploiting a compound’s physical properties to extract the compound of interest away from the other components of a mixture. This laboratory experiment will use liquid-liquid extraction to separate dextromethorphan from cough syrup. Gas chromatographic analysis will then be used on the extract to determine the purity of the extracted dextromethorphan. We will also determine the melting point of the isolated dextromethorphan and investigate how purity affects the melting point of a compound.