title: Anomalous temperature dependence of gas chromatographic retention indices of polar compounds on non-polar stationary phases.
abstract: Increasing the reliability of both GC and GC-MS identification requires appropriate interlaboratory reproducibility of gas chromatographic retention indices (I). Known temperature dependence, I(T), is the main source of non-reproducibility of these parameters. It can be approximated with a simple linear function I(T). However, since mid-1990s-beginning of 2000s some examples of anomalous temperature dependence, I(T), preferably for polar analytes on non-polar stationary phases were revealed independently by different authors. The effect implies the variations in the sign of the temperature coefficients β=dI/dT for selected compounds and, hence, the appearance of the I-extrema (usually, minima). The current work provides evidence that the character of the anomalous I(Т) dependences (ascending, descending, or with extrema) is strongly influenced by the amounts of analytes injected into the chromatographic column, but these anomalies appeared not to be connected directly with the mass overloading of separation systems. The physicochemical model is proposed to describe the observed anomalies of I(T) dependence. This model is based on three previously known principles of chromatography, namely: The superposition of these objectives allows understanding both the unusual temperature dependence of retention indices, and the influence of the amounts of polar analytes injected into GC column on the parameters of this dependence.
authors.affiliation: St. Petersburg State University, Institute for Chemistry, Universitetsky pr., 26, St. Petersburg 198504, Russia.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Pavlovskii
authors.affiliation: Research Center for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest XI, Magyar Tudósok krt. 2, Hungary.
authors.forename: Károly
authors.initials: K
authors.lastname: Héberger
authors.affiliation: St. Petersburg State University, Institute for Chemistry, Universitetsky pr., 26, St. Petersburg 198504, Russia. Electronic address: izenkevich@mail15.com.
authors.forename: Igor G
authors.initials: IG
authors.lastname: Zenkevich
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002849:Chromatography, Gas; D008956:Models, Chemical; D009930:Organic Chemicals / Q000737:chemistry*; D015203:Reproducibility of Results; D013696:Temperature
chemical_list: D009930:Organic Chemicals
keywords: Gas chromatography; Non-Polar phases; Polar analytes; Retention anomalies; Retention indices; Temperature dependence