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Hydrophilic vitamins play an important role in human health. The analysis of these compounds is indispensable for monitoring their content in pharmaceuticals and food in order to prevent some human diseases. The separation and identification of eight hydrophilic vitamins, i.e., B 1 , B 2 , B 3 , B 5 , B 6 , B 9 , B 12 , and C, was achieved by thin layer chromatography and Raman spectrometry. After chromatographic experiments, the best results were obtained using programmed multiple development. The unambiguous identification of superimposed spots can be done without using standards of vitamins.

The limit of detection (LOD) improvement in TLC determination of uranium and thorium in presence of other metal ions is presented in this paper. The mobile phase system contains iso-propyldithiophosphotic acid (i-PrDTP), as a complexing agent, in order to differentiate the studied species by modifying their retention. The paper reports the successful separation and the quantitative determination of uranium and thorium in the presence of other metal ions in the concentration range 2.5 30 p~g/p~l.

Mobile phase optimization is highly important in planar chromatography. Solvent selection based on experience and chromatographic intuition can be very time consuming when applied to complex mixtures. In these cases, more systematic strategies are needed. This paper presents a new mathematical model for the optimization of the mobile phase composition used for the separation of a mixture of 1,4-benzodiazepines and a comparison of this mathematical approach with other models.