The Influence of the Surface Chemistry of Sorbents on the Efficiency of Separation of Mixed S,N-Derivatives of 1,1-Dimethylhydrazine

Resumo

The influence of the surface chemistry of nonpolar sorbents (silica gel C18 and porous graphitized carbon), temperature, and liquid phase composition on the parameters of chromatographic retention of S,N-derivatives of 1,1-dimethylhydrazine (thiosemicarbazides) has been studied under the conditions of liquid chromatography. Experimental data have been compared with the results of preliminary estimates obtained for the adsorption characteristics of thiosemicarbazides using a molecular-statistical approache and determination of lipophility factor. Satisfactory agreement has been revealed between the experimental data and theoretical predictions. It has been shown that mixtures of ethyl-, allyl-, and phenylthiosemicarbazide are most efficiently separated by chromatography with the use of porous graphitized carbon packed into a Hypercarb column. The selectivity of this sorbent is 1.5 times higher than that of octadecyl silica gel packed into a Zorbax Eclipse XDB C18 column.