Use of a Simple Additive Scheme to Predict the GC Retention Indices of Aromatic Compounds with Different Structures Jorge Acevedo-Martı ´nez 1,& , Igor G. Zenkevich 2 , Ramo ´n Carrasco-Velar 3,& 1 Natural Science Faculty, University of Oriente, Patricio Lumumba s/n, Santiago de Cuba, Cuba; E-Mail: jacevedo@cnt.uo.edu.cu 2 Research Institute of Chemistry, St Petersburg State University, St Petersburg, Russia 3 Faculty of Bioinformatics, University of Informatics Sciences, La Habana, Cuba; E-Mail: rcarrasco@uci.cu Received: 2 March 2009 / Revised: 30 January 2010 / Accepted: 7 February 2010 Online publication: 18 April 2010 Abstract A simple algorithm is proposed for prediction of linear retention indices, RI, of organic compounds with different structures. The algorithm is based on the hypothesis that any structural moiety of a molecule contributes to gas chromatographic retention to a different extent, depending on its molecular environment. For a given moiety the mean structural increment (MSI) is calculated from the difference between the retention indices of two molecules, one containing it and one not, in different compound families. The mean of these values is the MSI for the corresponding moiety. The correlation between predicted and experimental values affords r 2 = 0.992 and the mean relative error is 1.65% for n = 92 compounds. Keywords Kova ´ ts retention index Structural increments QSRR QSPR Oxygenated compounds Introduction Gas chromatography (GC) is one of the most powerful tools in analytical chem- istry. Each compound has a property, the retention index, which can be used to aid identification of almost any com- pound under well-defined conditions. Retention in gas chromatography is a very complex process that involves the interaction of several intermolecular forces, for example dispersion (or London forces), orientation (dipole– dipole or Keesom forces), induction (dipole–induced dipole or Debye forces), electron donor–acceptor interactions, and hydrogen bonding. All these forces lead to defined partition of the solute between the gas and liquid phases [1–3]. Other factors, for example adsorption at the gas–liquid and liquid–support inter- faces, steric hindrance of substituent groups within the solute molecule, etc., can also affect retention [4, 5]. Although retention can be expressed in several forms, for example, retention time, retention distance, retention volume, corrected retention volume, etc., the form most often used is the Kova´ ts retention index [6], which was further developed by van den Dool and Kratz [7] for use in linear temperature pro- gramming. In this last case, the retention index is calculated by use of Eq. 1 RI ¼ 100 i t 0 R;x  t 0 R;nðnÞ t 0 R;nþi  t 0 R;nðnÞ þ 100 n ð1Þ where RI is the retention index, n is the number of carbon atoms in an n-alkane marker, and t 0 R;x ; t 0 R;n ðnÞ ; and t 0 R;nþi are, respectively, the adjusted retention times of the analyte, of the alkane marker with n carbon atoms eluting before the ana- lyte, and of the alkane marker with (n + i) carbon atoms eluting after the analyte. Analysis of organic reaction products by gas chromatography is a useful tool for determining the completeness of 2010, 71, 881–889 DOI: 10.1365/s10337-010-1587-9 0009-5893/10/05 Ó 2010 Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH Original Chromatographia 2010, 71, May (No. 9/10) 881