Fast, sensitive, and selective gas chromatography tandem mass spectrometry method for the target analysis of chemical secretions from femoral glands in lizards

Chemical signaling is a widespread mode of communication among living organisms that is used to establish social organization, territoriality and/or for mate choice. In lizards, femoral and precloacal glands are important sources of chemical signals. These glands protrude chemical secretions used to mark territories and also, to provide valuable information from the bearer to other individuals. Ecologists have studied these chemical secretions for decades in order to increase the knowledge of chemical communication in lizards. Although several studies have focused on the chemical analysis of these secretions, there is a lack of faster, more sensitive and more selective analytical methodologies for their study. In this work a new GC coupled to tandem triple quadrupole MS (GC-QqQ (MS/MS)) methodology is developed and proposed for the target study of 12 relevant compounds often found in lizard secretions (i.e. 1-hexadecanol, palmitic acid, 1-octadecanol, oleic acid, stearic acid, 1-tetracosanol, squalene, cholesta-3,5-diene, α-tocopherol, cholesterol, ergosterol and campesterol). The method baseline-separated the analytes in less than 7 min, with instrumental limits of detection ranging from 0.04 to 6.0 ng/mL. It was possible to identify differences in the composition of the samples from the lizards analyzed, which depended on the species, the habitat occupied and the diet of the individuals. Moreover, α-tocopherol has been determined for the first time in a lizard species, which was thought to lack its expression in chemical secretions. Globally, the methodology has been proven to be a valuable alternative to other published methods with important improvements in terms of analysis time, sensitivity, and selectivity.Jorge Sáiz thanks Belén Gómara for her kind offer of the analyt-ical instrumentation needed for the realization of this work. JorgeSáiz also thanks María José Malo Ara for the measuring instrumen-tation offered for this work. Roberto García-Roa and José Martínthank “El Ventorrillo” MNCN Field Station for use of their facil-ities. Financial support was provided by the Spanish Ministry ofEconomía y Competitividad, projects MICIIN-CGL2011-24150/BOS and MINECO CGL2014-53523- P. Roberto García-Roa thanks theSpanish Ministry of Economía y Competitividad for his FPI grant,number BES-2012-054387.Peer Reviewe