Chemical separations are an important part of an undergraduate chemistry curriculum. Sophomore students often get experience with liquid−liquid extraction in organic chemistry classes, but liquid−liquid extraction is not as often introduced as a quantitative sample preparation method in honors general chemistry or quantitative analysis classes. This experiment offers a relevant, interesting way to use liquid−liquid extraction and high-performance liquid chromatography (HPLC) to analyze popular lotions and creams for niacinamide content. After completing the experiment, students will have a better understanding of the extraction technique, Beer−Lambert law, and HPLC. The percent recovery from a spiked sample of Olay Original Active Hydrating Beauty Fluid was found to be 99.22% with a standard deviation of 0.01%.
A chemical separation experiment can be an interesting addition to an introductory analytical chemistry laboratory course. We have developed an experiment to extract FD&C Red Dye #40 from beverages containing cranberry juice. After extraction, the dye is quantified using colorimetry. The experiment gives students hands-on experience in using solid phase extraction to extract the red dye from other colorants in the red beverages. Students are also given experience with colorimetry, the Beer−Lambert law, and some wet chemical techniques. The recovery of the red dye from spiked cranberry juice was found to be 99% with a standard deviation of 2%.
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