| Abstract
| - It has been widely recognized that although ionic liquidsshould be colorless, they are frequently not. Coloredsamples appear to be pure by most analytical techniques(e.g., NMR spectroscopy, mass spectrometry, HPLC, andion chromatography), and there have been many attemptsto identify the source of color in our own laboratories andothersafter 20 years the best that can be said is that theimpurities are at a very low level (probably parts perbillion) with very high molar extinction coefficients. In thispaper, we do not identify these impurities but describe apractical method for removing them for spectrochemicalapplications. We clearly note that the method is not“green”, but we anticipate that it will only be applied tothe small volumes of ionic liquids required for fundamental spectroscopic studies in academia but not in industrialprocesses.
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