CAVITAND SORBENTS FOR THE SELECTIVE ADSORPTION OF ORGANIC-COMPOUNDS BY THE PURGE-AND-TRAP TECHNIQUE

Two cavitand sorbents were tested for the selective adsorption of diff erent analytes by using the purge-and-trap technique. Model mixtures o f esters and ketones covering a wide range of volatilities were used; the trapped compounds were thermally desorbed and analyzed by GC-MS. D iazanaphthalene-bridged cavitand proved to be highly selective toward aliphatic ketones with respect to aliphatic esters. Among ketones sele ctivity differences were observed depending both on the position of th e carbonyl group and on the length of the alkyl residues. The discrimi nation of structural isomers belonging to the same class was also demo nstrated for this receptor. The methylene-bridged cavitand having a mu ch reduced cavity was capable of efficiently trapping small organic mo lecules such as acetonitrile.