ISSN 1061-9348, Journal of Analytical Chemistry, 2010, Vol. 65, No. 13, pp. 1411–1419. © Pleiades Publishing, Ltd., 2010. Original Russian Text © M.A. Dikunets, E.D. Virus, E.N. Semenistaya, T.G. Sobolevsky, G.M. Rodchenkov, 2010, published in Mass-spektrometria, 2010, 6(4), pp. 307–314. 1411 INTRODUCTION Peroxisome proliferator-activated receptor ago- nists (PPAR) are a group of intranuclear proteins, which belong to the class of hormone receptors. They have been discovered only recently and in recent years the principal role of PPAR in the energetic homeosta- sis of animal and human organisms has been revealed [1–3]. The agonists of PPARδ are under clinical stud- ies at the moment, as the preparations for overweight treatment and normalization of the cholesterol level. So far they do not have patented names and are desig- nated by code numbers only. Each of the PPAR regulates the activity of a certain ensemble of genes affecting many processes in the intranuclear metabolism, the growth, differentiation, and apoptosis of a number of cells as well as some pathologic processes. PPAR are central regulators of lipid and carbohydrate metabolism, the evolution and differentiation of lipid tissue, modulators of gene expression in many tissues, including adipocytes, epi- thelia cells, smooth muscles, endothelium of the ves- sels, and macrophages. It was demonstrated that the activation of PPAR of the δ type stimulates the com- bustion of lipid cells in mice, these cells being the energy depot of living organisms [4]. The studies revealed that PPARδ activation specifically induces the expression of the genes that are necessary for the oxidation of fatty acids and energy liberation. In addi- tion, the unique ability of PPARδ agonist, GW501516 (1a), to increase the endurance capacity of mice by changing the metabolic processes in their muscular tissues was discovered [5]. The World Anti-Doping Agency included all the PPAR agonists similar to 1a in the Prohibited List starting from January 2009; the application of such a preparation is classified as a gene doping application [6]. A procedure was developed for the determination of such new potential doping prep- arations as ryanodine-calstabin complexes S-107 and JTV-519 selective modulator of androgen receptor S-40503 and agonist PPARδ in human blood plasma [7]. GW0742 (1b) and L-165,041 (2) are peroxisome proliferator-activated receptor agonists as well as 1a. Nowadays, no mass spectral data on the systematic study of these compounds are found in the literature. Obviously, the development of an efficient screening pro- cedure for doping control is impossible without the inves- tigation of mass spectral properties of the analytes. Therefore, the aim of the present study was to investigate the mass spectral properties of these compounds using high-performance liquid chromatography combined with tandem mass spectrometry (HPLCMS/MS) or with orbitrap high-resolution mass spectrometry (HPLC/HRMS) employing chemical ionization and atmospheric pressure electrospray ionization. EXPERIMENTAL Reagents and substances under consideration. Preparation 1a with a 99% fraction of the main com- ponent was obtained from the Centre for Preventive Doping Research of the Institute of Biochemistry of the German Sports University in Köln, while 1b and 2 with the same fraction of the main component were purchased from Sigma-Aldrich (Germany). The stan- dard solutions of the analytes (1 mg mL –1 ) were pre- pared by dissolving precisely weighted portions in Mass Spectrometry of Doping Preparations of a New Generation: Peroxisome Proliferator-Activated Receptor Agonists M. A. Dikunets, E. D. Virus, E. N. Semenistaya, T. G. Sobolevsky, and G. M. Rodchenkov Antidoping Center, Ministry of Sport, Tourism, and Youth policy of Russian Federation, Elizavetinsky per. 1, Moscow, 105005 Russia e-mail: dikunets@yandex.ru Received July 16, 2009; in final form, October 7, 2009 Abstract—The mass spectral properties of the peroxisome proliferator-activated receptor agonists (PPARδ) have been studied by high-performance liquid chromatography/tandem mass spectrometry (HPLCMS/MS) and high-performance liquid chromatography/high resolution mass spectrometry (HPLC/HRMS). Dissociation pathways of the investigated compounds under the conditions of collision activation have been proposed on the basis of the consolidated analysis of the data provided by these methods. Keywords: peroxisome proliferator-activated receptor agonists, PPARδ, mass spectrometry, high-perfor- mance liquid chromatography, tandem mass spectrometry, high resolution mass spectrometry, Orbitrap DOI: 10.1134/S1061934810130162 ARTICLES