Journal of Chromatography A, 1165 (2007) 136–143 Characterization of (E,E)-farnesol and its fatty acid esters from anal scent glands of nutria (Myocastor coypus) by gas chromatography–mass spectrometry and gas chromatography–infrared spectrometry Hyeunjoo Lee a , Steven Finckbeiner b , Jose S. Yu c , David F. Wiemer c , Thomas Eisner b , Athula B. Attygalle a,∗ a Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, NJ 07030, USA b Section of Neurobiology and Behavior, Department of Chemistry, Cornell University, Ithaca, NY 14853, USA c Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA Received 8 April 2007; received in revised form 17 May 2007; accepted 21 June 2007 Available online 27 June 2007 Abstract Several volatile compounds, including terpenoids, fatty alcohols, fatty acids and some of their esters, were identified from solvent extracts prepared from anal scent glands of nutria (a.k.a. coypu), a serious rodent pest ravaging wetlands in the USA. The major terpenoid constituents were identified as (E,E)-farnesol and its esters by a comparison of their gas chromatographic retention times, and electron-ionization (EI) and chemical-ionization (CI) mass spectra with those of authentic compounds. EI mass spectra of the four farnesol isomers are very similar, however, the ChemStation (Agilent) and GC–MS Solution (Shimadzu) software algorithms were able to identify the natural compound as the (E,E)-isomer, when a high-quality mass spectral library was compiled from reference samples and used for searching. Similarly, the esters were identified as those of (E,E)-farnesol. In contrast to EI spectra, the CI spectra of the (E,E)- and (E,Z)-isomers are distinctly different from those of the (Z,E)- and (Z,Z)-isomers. The intensities (I) of the peaks for the m/z 137 and 121 ions in the CI spectra offer a way of determining the configuration of the C-2 double bond of farnesols (for 2E isomers I 137 > I 121 , whereas for 2Z isomers I 137 < I 121 ). Moreover, the infrared spectrum of the (E,E)-isomer is distinctly different from those of the other three isomers in the 2962–2968 cm -1 and 2918–2922 cm -1 bands, which represent asymmetric CH 3 and CH 2 stretching vibrations, respectively. Finally, the GC retention indices of farnesol and farnesyl ester isomers determined from authentic samples were used to confirm all identifications. © 2007 Published by Elsevier B.V. Keywords: Nutria anal scent gland; Coypu; Myocastor coypus; Terpenoids; Farnesol isomers; Farnesyl ester isomers; Methanolysis; GC–MS; EI mass spectra; CI mass spectra 1. Introduction Farnesol, a sesquiterpene alcohol that exists as four isomers (Fig. 1), is widely distributed in nature as an odoriferous com- ponent of leaves, fruits, and roots of many higher plants [1–4]. Moreover, farnesol in glandular secretions of insects [5–7], and mammals [8–12] including elephants, is known to play a role in mediating chemical communication behaviors such as ter- ritorial marking, individual recognition, and mate attraction. A variety of biological functions such as antibacterial effects ∗ Corresponding author. Tel.: +1 201 2165575. E-mail address: athula.attygalle@stevens.edu (A.B. Attygalle). [4,13], quorum-sensing, and suppression of filamentation in some fungi [14,15], have been attributed to farnesol. Some farnesol derivatives are known to act as key biosynthetic interme- diates [7,14,16,17]. Furthermore, farnesol is known to regulate tumor cell proliferation and apoptosis, hence it is considered an anti-cancer agent. [9,16–19]. Many analytical procedures have been reported for separat- ing and identifying farnesol isomers. Although HPLC and NMR spectrometric [20–24] techniques have been used, GC–MS and GC–FTIR are the methods of choice, primarily because of better sensitivity [25]. Farnesol from natural samples is often avail- able only in limited amounts. Thus, the characterization of the individual farnesol isomers is not always straightforward. Apparently, both mass and IR spectral data are required to 0021-9673/$ – see front matter © 2007 Published by Elsevier B.V. doi:10.1016/j.chroma.2007.06.041