1 / 13

Understanding Extraction: Techniques, Benefits, and Challenges in Compound Analysis

Extraction is a critical process in analytical chemistry used to selectively transfer compounds of interest to another medium for further analysis. This lecture covers the importance of extraction techniques, such as liquid-liquid and supercritical fluid extraction, highlighting the need for sample clean-up and concentration to mitigate contamination and losses during sampling. The role of physical properties, polarity control, and the implications of equilibrium versus exhaustive extraction strategies will also be discussed, providing insights into effective extraction methods and their respective challenges.

tuesday
Télécharger la présentation

Understanding Extraction: Techniques, Benefits, and Challenges in Compound Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 5 Sample Preparation

  2. What is an extraction? Move compounds of interest ‘selectively’ to another media.

  3. Why extract? • Sampling media cannot be analyzed • Clean-up • Concentration

  4. Why simplify extractions? • Possibility of contamination • All steps involve some loss • Random errors possible at all steps

  5. Extractions exploit the physical properties of the compounds of interest Air KOA KAW Octanol (hydrophobic) Water KOW

  6. Small Non-polar (non-interactive) Air KOA KAW Octanol (hydrophobic) Small Polar (interactive) Water KOW Large Non-polar (non-interactive)

  7. pH can control polarity Acidic compounds Low pH (acidic) High pH (basic) nonpolar Polar (charged) Basic compounds Low pH (acidic) High pH (basic) Polar (charged) nonpolar

  8. Equilibrium vs. Exhaustive Extraction • All extractions involve an equilibrium Hexane • Exhaustive extractions usually involve repeating the process until all of the analyte is essentially in only one phase Water

  9. 90% 99% ext 1 ext 2 10% 1% Liquid-Liquid Extraction (Exhaustive Extraction) KOW = 10 0% 100% initial

  10. Super Critical Fluid Extraction (Exhaustive Extraction) Advantages • Very effective • Non-toxic • Easy to remove solvent Disadvantages • Expensive

More Related