Bi-Curious Laboratory

I created our second lab this semester in an attempt to integrate my research experience and expertise with an organic chemistry laboratory. I have been working with countercurrent chromatography (CCC) for the past eight years. The cornerstone of CCC is the use of two-phase solvent systems to isolate target analytes and separate complex mixtures of compounds. In this lab, students explore two-phase solvent system formulations by starting with a “classic” hexane-ethyl acetate-methanol- water (1:1:1:1 v/v) mix and then systematically modifying it. The challenge was to find accessible ways to generate qualitative and quantitative data. Student measured the volumes and masses of both upper and lower phases. They also determined settling time and the shape of the meniscus between the two phases (total volume approximately 16 ml) in a 20 ml vial. Other more qualitative observations were to determine which phase settles fastest, clarity/turbidity of the phases, and size of settling bubbles. A nice touch was to add Reichardt’s dye to both phases and observe the coloration. Visible spectra were taken of select samples. Reichardt’s dye is a fascinating solvatochromic dye that turns a wide range of colors depending on the polarity of the solvent. Unfortunately, its range is somewhat limited as it is insoluble in water and hexane.


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