Home
Resources
Publications
Analysis of Exemestane and 17β-hydroxyexemestane in Human Urine by Gas chromatography/mass Spectrometry: Development and Validation of a Method Using MO-TMS Derivatives

Analysis of Exemestane and 17β-hydroxyexemestane in Human Urine by Gas chromatography/mass Spectrometry: Development and Validation of a Method Using MO-TMS Derivatives

Gustavo de A Cavalcanti, Bruno C Garrido, Felipe D Leal, Monica C Padilha, Xavier de la Torre, Henrique M G Pereira, Francisco R de Aquino Neto

Rapid Commun Mass Spectrom. 2010 Nov 30;24(22):3297-302.

PMID: 20973004

Abstract:

Trimethylsilylation of anabolic agents and their metabolites is frequently achieved by using the derivatization mixture N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA)/NH(4)I/2-mercaptoethanol. Nevertheless, artifacts were formed when this mixture was employed in the monitoring of exemestane and its main metabolite 17β-hydroxyexemestane prior to GC-MS analysis. These artifacts were identified as the N-methyltrifluoroacetamide (MTFA) and trimethylsiloxyethylmercapto products of the respective trimethylsilyl (TMS) derivatives. Furthermore, artifact formation was evaluated taking the structure (1,4-diene-3-keto-6-exomethylene) of the compounds into account. Although these artifacts are relevant for investigations regarding the derivatization process and may be of interest in many fields, they are detrimental to cope with the requirements of the World Anti-Doping Agency (WADA) in terms of the limits of detection (LODs) required. To overcome this issue, a method using an alternative derivatization was proposed: formation of methyloxime-TMS derivatives through double derivatization using O-methylhydroxylamine/pyridine and MSTFA/TMS imidazole after enzymatic hydrolysis and liquid-liquid extraction. Samples from an excretion study after administration of exemestane to healthy volunteers were analyzed by the proposed method and detection of both exemestane and its main metabolite was possible. This method showed excellent results for both analytes meeting the LODs required for antiestrogenic agents (50 ng/mL) established by WADA. The method was validated for the main metabolite, it was robust and cost-effective for qualitative and quantitative purposes, with LOD and LOQ of 10 ng/mL and 25 ng/mL, respectively.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP8077358	1-(Trimethylsilyl)imidazole - Pyridine mixture		8077-35-8	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: