Influence of Calixarenes on Chromatographic Separation of Benzene or Uracil Derivatives Olga I. Kalchenko, Sergiy O. Cherenok & , Andriy V. Solovyov, Vitaly I. Kalchenko Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska Str. 5, 02660 Kyiv, 94, Ukraine; E-Mail: vik@ioch.kiev.ua Received: 5 November 2008 / Revised: 13 March 2009 / Accepted: 10 June 2009 Online publication: 9 July 2009 Abstract The addition of calix[4]arenes to MeCN/H 2 O or MeOH/MeCN/THF/H 2 O mobile phases improves LC separation of benzene or uracil derivatives on Separon SGX C18 or Separon SGX NH 2 supports. Structure of the calixarenes and their host–guest supramolecular com- plexes with the analytes are discussed in context of the LC separation. Keywords Column liquid chromatography Chromatographic characteristics Adsorption isotherms Calix[4]arenes Introduction Calix[n]arenes—macrocyclic oligomers consisting of phenolic units linked by methylene spacers are well known com- plexants of cations, anions and organic molecules [1–10]. Due to the ability to form supramolecular complexes with organic molecules, calixarenes have been applied for the design of stationary chromatography phases [11–18] or additives to mobile phases [19] improv- ing LC separation of analytes. In this work chromatographic char- acteristics of the number of calix[4]res- orcinarene and calix[4]arene derivatives (compounds 1–6 on the scheme, Fig. 1) were determined and their adsorption isotherms on chromatographic supports Separon SGX C18 and Separon SGX NH 2 were calculated. The influence of the calixarene additives to mobile phases on selectivity of chromatographic sepa- ration of some benzene or uracil deriv- atives was studied. Experimental Reagents Compounds for the chromatographic investigation were synthesized according to the procedures described earlier: 1 [20], 2–6 [21]. Acetonitrile, methanol and tetrahydrofuran were obtained from Acros Organics. Equipment LC analysis was performed using a high pressure liquid chromatograph manu- factured by the Laboratorni Prystroje (Czech Republic). The columns (150 9 3.3 mm i.d.) were packed with Separon SGX 18 or Separon SGX NH 2 . LC Analysis Chromatographic experiments were performed with isocratic conditions 2009, 70, 717–721 DOI: 10.1365/s10337-009-1229-2 0009-5893/09/09 Ó 2009 Vieweg+Teubner | GWV Fachverlage GmbH Original Chromatographia 2009, 70, September (No. 5/6) 717