title: Thermodynamic-based retention time predictions of endogenous steroids in comprehensive two-dimensional gas chromatography.
abstract: This work evaluates the application of a thermodynamic model to comprehensive two-dimensional gas chromatography (GC × GC) coupled with time-of-flight mass spectrometry for anabolic agent investigation. Doping control deals with hundreds of drugs that are prohibited in sports. Drug discovery in biological matrices is a challenging task that requires powerful tools when one is faced with the rapidly changing designer drug landscape. In this work, a thermodynamic model developed for the prediction of both primary and secondary retention times in GC × GC has been applied to trimethylsilylated hydroxyl (O-TMS)- and methoxime-trimethylsilylated carbonyl (MO-TMS)-derivatized endogenous steroids. This model was previously demonstrated on a pneumatically modulated GC × GC system, and is applied for the first time to a thermally modulated GC × GC system. Preliminary one-dimensional experiments allowed the calculation of thermodynamic parameters (ΔH, ΔS, and ΔC p ) which were successfully applied for the prediction of the analytes' interactions with the stationary phases of both the first-dimension column and the second-dimension column. The model was able to predict both first-dimension and second-dimension retention times with high accuracy compared with the GC × GC experimental measurements. Maximum differences of -8.22 s in the first dimension and 0.4 s in the second dimension were encountered for the O-TMS derivatives of 11β-hydroxyandrosterone and 11-ketoetiocholanolone, respectively. For the MO-TMS derivatives, the largest discrepancies were from testosterone (9.65 ) for the first-dimension retention times and 11-keto-etiocholanolone (0.4 s) for the second-dimension retention times.
authors.affiliation: Instituto de Química, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, RJ, 21941-909, Brazil.
authors.forename: Aline C A
authors.initials: AC
authors.lastname: Silva
authors.forename: Heshmatollah
authors.initials: H
authors.lastname: Ebrahimi-Najafadabi
authors.forename: Teague M
authors.initials: TM
authors.lastname: McGinitie
authors.forename: Alessandro
authors.initials: A
authors.lastname: Casilli
authors.forename: Henrique M G
authors.initials: HM
authors.lastname: Pereira
authors.forename: Francisco R
authors.initials: FR
authors.lastname: Aquino Neto
authors.forename: James J
authors.initials: JJ
authors.lastname: Harynuk
mesh_terms: D002849:Chromatography, Gas / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*; D013256:Steroids / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D013256:Steroids