Journal of Chromatography A, 1218 (2011) 5852–5857 Contents lists available at ScienceDirect Journal of Chromatography A j our na l ho me p ag e: www.elsevier.com/locate/chroma Determination of coumaphos, chlorpyrifos and ethion residues in propolis tinctures by matrix solid-phase dispersion and gas chromatography coupled to flame photometric and mass spectrometric detection Andrés Pérez-Parada, Marcos Colazzo, Natalia Besil, Lucía Geis-Asteggiante, Federico Rey, Horacio Heinzen ∗ Pharmacognosy and Natural Products, Facultad de Química, Universidad de la República (UdelaR), General Flores 2124, 11800 Montevideo, Uruguay a r t i c l e i n f o Article history: Received 24 March 2011 Received in revised form 24 June 2011 Accepted 27 June 2011 Available online 3 July 2011 Keywords: Acaricides Coumaphos Pesticide residues Propolis tinctures Gas chromatography a b s t r a c t A new analytical method has been developed and successfully evaluated in routine application for the quantitative analysis of a selected group of organophosphate pesticides (coumaphos, chlorpyrifos and ethion) which can be found at trace levels in propolis tinctures (ethanolic propolis extracts); a valuable commodity used as raw material in the food and pharmaceutical industries for which there have been few attempts for pesticide residue analysis reported in the literature. The proposed methodology is based on matrix solid phase dispersion (MSPD) using aluminum sulfate anh. a novel dispersant material and subsequent column chromatography clean-up in silica gel prior to gas chromatography (GC) with both flame photometric detector (FPD) and mass spectrometry (MS) detection used for the routine quantifica- tion and identification of the residues, respectively. The limits of detection, for coumaphos, chlorpyrifos and ethion were below 26.0 g/kg in FPD and 1.43 g/kg for MS detection. Mean recoveries were in the range of 85–123% with RSD values below 13%, which suggests that the proposed method is fit for the purpose of analyzing pesticides in propolis tinctures containing high concentration of polyphenolics. The method has been successfully applied in our laboratory for the last 2 year in the analysis of real propolis tinctures samples. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Propolis is a valuable by-product from bees. Due to its well known biological activities such as antibacterial, antiviral, fungici- dal, anti-inflammatory and anticancer properties, it is widely used in pharmaceutical and food industries. Propolis has been exten- sively used in dermal pharmaceutical preparations and nowadays it is increasingly being used as food or dietary supplement [1]. Pes- ticide residues in propolis arise from two main sources; either from contamination from agricultural practices or due to pesticide appli- cation in hives, to prevent parasitic acaroids like Varroa destructor [2–5]. Nowadays, few data are available on the influence of con- taminants in propolis quality. Acaricides that are widely employed in apiculture are common propolis contaminants although nei- ther published multiresidue method for residue determination nor residue regulation is given for this product and apicultural prac- ∗ Corresponding author. Tel.: +598 29244068; fax: +598 29241060. E-mail address: heinzen@fq.edu.uy (H. Heinzen). tices. Coumaphos is one of the preferred worldwide used acaricide for Varroasis control [2,6,7]. Since propolis consumption increased, contaminants are now considered of interest as described in recent publications for trace analysis of tetracyclines [8], chloramphenicol [9], polycyclic aro- matic hydrocarbons [10] and pesticide residues [11,12] in raw propolis and processed propolis [13]. However, propolis tinctures are the actual commodity used, that is obtained after raw propolis processing which involves water washing and the removal of waxes through resin dissolution in ethyl alcohol with further filtration to separate insoluble waxes and remaining material [1]. Processed propolis gives a highly pigmented sticky gum with different physic- ochemical properties and composition from the raw material. Residue determination in propolis presents an analytical challenge because of the high polyphenolic composition of this matrix and the chemical variability of the samples depending on different geo- graphical or botanical origins [12,14]. In this sense, clean-up steps must be exhaustive to yield purified extracts for proper routine gas chromatographic (GC) analysis. To the best of our knowledge, attempts for GC residue determination of pesticides in propolis are performed using general methods in products from animal or 0021-9673/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2011.06.097