Journal of Chromatography A, 1251 (2012) 240–243 Contents lists available at SciVerse ScienceDirect Journal of Chromatography A j our na l ho me p ag e: www.elsevier.com/locate/chroma Short communication Thin layer chromatography in the separation of unsaturated organic compounds using silver-thiolate chromatographic material James T. Dillon a , José C. Aponte b , Yih-Jin Tsai b , Yongsong Huang b,∗ a Department of Chemistry, Brown University, 324 Brook Street, Providence, RI 02906, USA b Department of Geological Sciences, Brown University, 324 Brook Street, Providence, RI 02906, USA a r t i c l e i n f o Article history: Received 22 April 2012 Received in revised form 13 June 2012 Accepted 14 June 2012 Available online 21 June 2012 Keywords: Silver-ion chromatography Thin layer chromatography Silver-thiolate chromatographic material Fatty acid methyl esters Polycyclic aromatic hydrocarbons a b s t r a c t We report the use of silver-thiolate chromatographic material (AgTCM) as a stable material for use in TLC. The AgTCM stationary phase operates under the same principles as silver-ion chro- matography, separating compounds by degree of unsaturation; however, the AgTCM stationary phase shows considerable advantages over Ag-TLC in terms of light stability and shelf lifetime. We demonstrate the light stability of the AgTCM-TLC and its application for separations based on the degrees of unsaturation using fatty acid methyl esters (FAMEs) and polycyclic aromatic hydrocarbons (PAHs). © 2012 Elsevier B.V. All rights reserved. 1. Introduction Thin layer chromatography (TLC) is a popular and widely used chromatographic technique utilized for a variety of applications including analysis and purification. Although the chromatographic resolution seen in TLC is typically lower than that of high perfor- mance liquid chromatography (HPLC), a number of advantages still make TLC an indispensable analytical tool [1–3]. The equipment needed for TLC is relatively inexpensive and can easily be set up and operated in many laboratories. The quantity of solvent required for TLC is often much smaller than HPLC and can save significant amounts of consumables and waste removal. The inexpensive and disposable nature of individual TLC plates allow for it to be used to identify impurities that may cause damage to HPLC columns and detectors. TLC is widely used in organic synthesis for moni- toring reactions and the identification of product formation. TLC plates also allow for multiple samples to run in parallel to each other and normal TLC run times are often shorter than HPLC. These advantages have resulted in extensive development and applica- tions of TLC for analytical and preparative applications. Unmodified silica gel or C 18 functionalized silica are typically used as the sta- tionary phase for many TLC methods; however, more specialized ∗ Corresponding author. Tel.: +1 401 863 3822; fax: +1 401 863 2058. E-mail address: yongsong huang@brown.edu (Y. Huang). stationary phases are needed for the specialized efficient separation of organic compounds. Since its conception in the 1960s, silver-ion chromatography has been a useful chromatographic method for the separation of com- pounds by degree of unsaturation [4,5]. The application of silver-ion chromatography to TLC has been developed for a range of appli- cations, and has been an indispensable technique for the analysis of lipids [6–9]. Silver-ion TLC (Ag-TLC) plates can be prepared by impregnating a silver salt (where the most widely used salt is silver nitrate) onto a silica surface typically containing a calcium sulfate binder. Silver-ion TLC does have drawbacks however. The primary sta- tionary phase used in Ag-TLC (SiO 2 + AgNO 3 ) is light sensitive and normal levels of atmospheric humidity are known to have a considerable effect on the reproducibility of these plates [10]. All Ag-TLC plates must therefore be stored in a desiccator and shielded from light. As a result, even under ideal storage con- ditions, Ag-TLC plates cannot be stored for prolonged periods of time without suffering considerable damage to the stationary phase. Previously we reported that silver-thiolate chromatographic material (AgTCM) operates under the same principle as classical silver-ion chromatography by separating compounds based on the degree of unsaturation; however, the AgTCM material is stable over extended periods of time [11,12]. AgTCM offers higher compound recovery compared to other silver-ion based stationary phases, which is promising for purification purposes [11]. The AgTCM 0021-9673/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chroma.2012.06.042