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In this video, a DPX extraction of an aqueous mixture of 2 different dyes is performed. One dye is acidic (blue), and the other dye is nonpolar
(red). The first step of the extraction is a conditioning step using methanol (middle test tube). After the methanol is dispensed, the sample solution (first test
tube on the left) is drawn into the DPX tip and mixed with air. After equilibration (30 s), the solution is expelled. This step is repeated with a short equilibration
time (10 s) to improve the extraction efficiency, and after expelling the dye solution from the DPX tip, the solution is noted to be colorless indicating that the
dyes were completely extracted from the solution.
The elution of the dyes was accomplished with 2 solvents. The 1st elution solvent, methanol, elutes the acidic blue dye. The 2nd elution solvent was methylene chloride, and high recovery of the nonpolar red dye was achieved. Both elution steps used just 10 second equilibration times. Noteworthy is that the solvent volumes were much less than the sample solution, meaning that a built-in concentration factor was achieved. Some DPX applications may not require any solvent evaporation or additional concentration steps!
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