HPLC methods parameter modification

The trends among the parameters studied by the UNCA racemization assay have been borne out when other activation methods are used. By a modification of chiral HPLC procedure below, the assay can be used to study any method of activation (for example, uronium or phosphonium methods), keeping in mind that the activation must be rapid and that epimerization by multiple mechanisms becomes possible. These findings also hold for solid-phase synthesis reactions. 

Extraction of Active Compounds from Food. Vitamins are the group of compounds more usually extracted from foods using SFE (83). A method for the analysis of the natural contents of vitamins A and E in milk powder based on SFE, a miniaturized alkaline saponification procedure, and HPLC was proposed by Turner and Mathiasson (84). Modifications of the sample matrix, the combination of static and dynamic extraction modes, and the effect of changes in extraction parameters such as temperature, flow rate, time, collection solvent, and collection temperature were optimized, obtaining recoveries of 99% and 96% for vitamins A and E, respectively. Another method for the determination of vitamins A and E based on the coupling of SFE-enzymic hydrolysis-HPLC has also been proposed providing recoveries between 79% and 152% (85). 

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