313 ISSN: 1469-0667 © IM Publications LLP 2016 doi: 10.1255/ejms.1442 All rights reserved EUROPEAN JOURNAL OF MASS SPECTROMETRY Letter Thermal desorption combined with atmospheric pressure photo ionization for the analysis of volatile compounds and its possible applications Yury Kostyukevich, a,b,c,d Ludmila Borisova, e Alexey Kononikhin, b,d Igor Popov, c,d Eugene Kukaev c,d and Eugene Nikolaev a,b,c,d a Skolkovo Institute of Science and Technology Novaya St., 100, Skolkovo 143025 Russian Federation. E-mail: y.kostyukevich@skoltech.ru b Institute for Energy Problems of Chemical Physics Russian Academy of Sciences Leninskij pr. 38 k.2, 119334 Moscow, Russia c Emanuel Institute for Biochemical Physics Russian Academy of Sciences Kosygina st. 4, 119334 Moscow, Russia d Moscow Institute of Physics and Technology, 141700 Dolgoprudnyi, Moscow Region, Russia e National Research University Higher School of Economics, 20 Miasnitskaya Ulitsa, Moscow 101000, Russia We report an approach to study volatile organic compounds based on thermal desorption combined with atmospheric pressure photo ionization. The approach allows the sequential evaporation of different fractions of the sample, which simplifes the mass spectrum. We have applied the developed method for the detection of petroleum in vegetable oil. We have shown that in the negative mode, ions of fatty acids corresponding to vegetable oil dominates, while in the positive mode under relatively low temperature the light fraction of petroleum rapidly evaporates making it easy detectable. Keywords: thermal desorption, APPI, photoionization, mass spectrometry, FT-ICR Introduction Introduction The development of ionization techniques working under atmospheric pressure has received considerable attention in past decades. Thermospray, 1 electrospray (ESI), 2 atmospheric pressure photo ionization (APPI) 3 and atmospheric pressure chemical ionization (APCI) 4 approaches have been developed and are now widely used. Recently, many ionization methods for ambient mass spectrometry have been proposed: desorp- tion electrospray ionization (DESI), 5 direct analysis in real time (DART), 6 electrospray laser desorption/ionization (ELDI), 7,8 laser ablation electrospray ionization (LAESI), 9 matrix- assisted laser desorption electrospray ionization (MALDESI) 10 and many others. 11 But all these techniques allow only ioniza- Y. Kostyukevich et al., Eur. J. Mass Spectrom. 22, 313–317 (2016) Received: 16 September 2016 n Accepted: 21 September 2016 n Publication: 30 November 2016