Analise cromatografica de acidos carboxilicos




Ion-exclusion partition chromatography is a technique used to separate weak acids, amino acids, sugar, alcohols and other substances on a cation-exchange column. Because of Donnan exclusion, ionic material is rejected by this exchange resin. However, non-ionic substances can undergo partítíon between the stationary phase and the mobile phase. Separations are based on polar and van der Waals interactions between the solute and the resin. The chromatographic behavior of a large number of organic acids and their retention times with respect to acetic acid were determinated. Based on the fact that the resin used is a strong cation exchanger in the.H-form, it is not necessary to regenerate it. Several parameters, such as the resin crosslinkage, the pH and the length of the column were studied, to observe their effects on sample resolutions. The retention times of the acids increase greatly as the cosslinkage decreases. The elution order of the acids may be correlated, in a general way, with their pKa values. Using mineral acids as eluent makes the separation of moderately strong acids easier since the separation cannot be obtained using water as mobile phase. Increasing the column length resul ted in greater retention times, but the resolution for carboxylic acid separations was not improved.


analise cromatografica acidos carboxilicos

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