is to find an optimum stationary phase-mobile phase system.
TLC is the method of choice when many samples must be compared, when flexibility is important, and when rapid quantitative data are needed at low cost per sample. Unfortunately structural analogues are difficult to separate in one chromatographic run, and this is the case in hydrophilic vitamins investigations. Multidimensional chromatography is a popular method for separation of multicomponent mixtures. TLC gives the possibility to perform two-dimensional separations either by use of the same stationary phase with different mobile phase systems [13–16] or by using stationary phase gradient [17–20]. The highest resolution in separation is achieved by combining two systems with different selectivity, such as the case of separations performed on two different stationary phases coated side by side. The stationary phases are usually a normal phase with adsorption separation mechanism, and a reversed phase with partition separation mechanism [15]. Different combinations of adsorbents have been reported: silica gel + alumina, cellulose + silica gel, poliamide + silica, poliamide + cellulose [21]. Due to different mechanisms of interaction, the separations on such adsorbents combinations enable obtaining a complete resolution of very complex samples.
is to find an optimum stationary phase-mobile phase system.TLC is the method of choice when many samples must be compared, when flexibility is important, and when rapid quantitative data are needed at low cost per sample. Unfortunately structural analogues are difficult to separate in one chromatographic run, and this is the case in hydrophilic vitamins investigations. Multidimensional chromatography is a popular method for separation of multicomponent mixtures. TLC gives the possibility to perform two-dimensional separations either by use of the same stationary phase with different mobile phase systems [13–16] or by using stationary phase gradient [17–20]. The highest resolution in separation is achieved by combining two systems with different selectivity, such as the case of separations performed on two different stationary phases coated side by side. The stationary phases are usually a normal phase with adsorption separation mechanism, and a reversed phase with partition separation mechanism [15]. Different combinations of adsorbents have been reported: silica gel + alumina, cellulose + silica gel, poliamide + silica, poliamide + cellulose [21]. Due to different mechanisms of interaction, the separations on such adsorbents combinations enable obtaining a complete resolution of very complex samples.
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