Skip to Content
Merck
  • Thermodynamic-based retention time predictions of endogenous steroids in comprehensive two-dimensional gas chromatography.

Thermodynamic-based retention time predictions of endogenous steroids in comprehensive two-dimensional gas chromatography.

Analytical and bioanalytical chemistry (2015-04-08)
Aline C A Silva, Heshmatollah Ebrahimi-Najafadabi, Teague M McGinitie, Alessandro Casilli, Henrique M G Pereira, Francisco R Aquino Neto, James J Harynuk
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
2-Mercaptoethanol, SAJ special grade, ≥99.0%
Sigma-Aldrich
2-Mercaptoethanol, ≥99.0%
Sigma-Aldrich
Ammonium iodide, SAJ special grade, ≥99.5%
Sigma-Aldrich
2-Mercaptoethanol, BioUltra, for molecular biology, ≥99.0% (GC)
Sigma-Aldrich
Ammonium iodide, 99.999% trace metals basis
Sigma-Aldrich
2-Mercaptoethanol, ≥99.0%
Sigma-Aldrich
trans-Dehydroandrosterone, ≥99%
Sigma-Aldrich
17α-Methyltestosterone, solid (photosensitive)
Sigma-Aldrich
2-Mercaptoethanol, for molecular biology, suitable for electrophoresis, suitable for cell culture, BioReagent, 99% (GC/titration)
Supelco
Testosterone solution, 1.0 mg/mL in acetonitrile, ampule of 1 mL, certified reference material, Cerilliant®
Sigma-Aldrich
Testosterone, ≥98%