The Analysis of Complex Organic Compounds by Gas Solid Chromatography on Various Phthalocyanines

Abstract

The adsorption properties of the surfaces obtained by coating various phthalocyanines (metal free, copper, nickel, cobalt and zinc) on graphitized carbon black have been studied. The graphitized carbon black allows highly efficient columns to be obtained because of its large surface area and its non-selective adsorption properties. It also allows the adsorptive behavior of each phthalocyanine to be determined since the effect of the support is kept very small. Using GSC we have compared the selectivities of the various phthalocyanines and determined their affinity towards different organic functions (saturated, unsaturated and aromatic hydrocarbons, phenols, amines, pyridines, alcohols, ethers, esters). The adsorptive properties of all the phthalocyanines studied here are different and this makes it possible to understand better the conditions leading to separations in GSC. The phthalocyanines which have a weak specificity towards polar compounds like ethyl ether, acetone, methyl proprionate, and suitable adsorbents for the separation of alcohols, phenols, aromatic bases (pyridine, picolines, aniline, …). The adsorption enthalpy of these compounds is relatively low and the elution peaks are symmetrical. Cobalt phthalocyanine is very interesting in practice for it is a specific adsorbent towards the aromatic rings and a non-specific adsorbent towards OH or NH2 groups. The separation of phenols and aromatic amines on this adsorbent depends on the position of the methyl substituant on the aromatic ring; the elution peaks are symmetrical.