3. Extraction yields and quantitative analysis

Yield is defined as the ratio between the quantity of solute extracted and the quantity percolated. In theory, this yield is 100%, if the percolated volume is less than the end-of-fixation volume V _f . As a result, the yield of a solute depends on the volume percolated and the volume at the end of fixation of this solute, these two parameters being linked to the physico-chemical properties of the solute (n-octanol/water partition coefficient (lg P), pK _a , solubility...) and to the nature of the adsorbent chosen.

• For the delayed extraction method, the measurement of yields is based on the comparison of the signal detected (area or peak height) after injection of the extract into the chromatographic system with the signal obtained by direct injection of...