Food Anal. Methods DOI 10.1007/s12161-014-9930-7
Development and Validation of a Multi-residue Method for the Determination of Pesticides in Chios Mastic Gum by QuEChERS and Liquid Chromatography–Tandem Mass Spectrometry A. K. Psoma & I. N. Pasias & A. A. Bletsou & N. S. Thomaidis
Received: 27 March 2014 / Accepted: 26 June 2014 # Springer Science+Business Media New York 2014
Abstract A simple, rapid, and sensitive method was developed for the simultaneous determination of 21 pesticides from different chemical classes (organophosphorus, triazines, carbamates, and anilinopyrimidine pesticides) in Chios mastic gum (Pistacia lentiscus L. var. Chia). Quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique was used for the extraction of the target analytes; the mastic gum samples were initially extracted with acetonitrile (ACN), and then, the extracts were purified by dispersive solid-phase extraction using primary secondary amine (PSA) and C18 as sorbents. The determination of pesticides in the final extract was carried out by liquid chromatography coupled with tandem mass spectrometry with electrospray ionization (LC-ESI-MS/MS). The method was validated for linearity, accuracy, precision (repeatability and inter-laboratory reproducibility), limits of detection and quantification, and the matrix effect factor. Recoveries of the pesticides fortified at 5, 50, and 500 ng g−1 ranged from 49.7 % (quinalphos) to 127 % (pirimiphos-ethyl) and reproducibility (RSD R , n = 2 × 3) ranged from 4.4 % (propham) to 20 % (pirimiphos-methyl, propham, and triazophos). The detection limits of the method were 0.8 (mecarbam, pyrazophos) to 23 ng g−1 (parathion-ethyl). The uncertainty of the method was also calculated based on the Eurachem/Citac Guidelines, and the contribution of each independent parameter was investigated.
A. K. Psoma : I. N. Pasias : A. A. Bletsou : N. S. Thomaidis (*) Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece e-mail:
[email protected]
Keywords Chios mastic gum . Pesticides . LC–MS/MS . QuEChERS . Dispersive solid-phase extraction . Uncertainty
Introduction Mastic gum is the resin obtained as an exudate from the trunk and branches of Pistacia lentiscus L. var. Chia, an evergreen shrub belonging to the family Anacardiaceae and uniquely cultivated in the southern island of Chios, Greece. Mastic gum has been used for more than 2,500 years in traditional Greek medicine (Paraschos et al. 2012). It is used as a seasoning in Mediterranean cuisine, as a flavoring in food products and beverages, and in the production of chewing gum and in perfumery (Lemonakis et al. 2011). Recently, modern scientific researches have proved its numerous diverse pharmaceutical and biomedical properties (Dimas et al. 2012). Mastic has in vitro antibacterial and antifungal activity (Magiatis et al. 1999), is effective against Helicobacter pylori in vitro and in vivo (Paraschos et al. 2007) also at Crohn’s disease (Kaliora et al. 2007) and colon (Balan et al. 2007) or prostate cancer (He et al. 2006). Mastic also protects against functional dyspepsia (Dabos et al. 2010a and in some cases eradicates H. pylori in humans (Dabos et al. 2010b). Chios mastic gum is nowadays used extensively as a constituent of herbal drugs or functional foods (Lemonakis et al. 2011). More than 1,000 substances are considered to be used for pest control; however, it is one of the most extensively regulated chemical groups regardless the large number of pesticides (Tomlin 2003). Organophosphorus (OP) and carbamate (CB) pesticides are among the most common and most toxic insecticides used today, not only for crop protection but also for industrial or home purposes. They are widely used as
Food Anal. Methods
cholinesterase-inhibiting agents. In addition to their insecticidal activity, these chemicals have considerable advantages over organochlorine pesticides (OCPs) because of their low environmental persistence (Bachmann et al. 2000). They have been used increasingly since the 1970s when environmentally persistent OCPs, such as DDT and dieldrin, were banned for use in the USA. OP and CB pesticides can adversely affect the human nervous system even at low levels of exposure (Tomlin 2003). The problem becomes more serious when bioaccumulation of these lipophilic compounds is taken into consideration (Beyer and Biziuk 2008). The U.S. Environmental Protection Agency has classified OPs as highly or moderately toxic (U.S. Environmental Protection Agency 2006). It is of a paramount importance to be able to clarify through sufficient analytical laboratory methodologies that there are no residues of pesticides in products intended for human use either as food or as herbal drug. The pesticide residues must not exceed the maximum residual level (MRL) of the Commission Regulation EC No 839/2008 (European Commission 2008) and European Pharmacopoeia (European Pharmacopoeia 2011) not only for the protection of human health but also for international trade and regulatory control. Up until now, many sample preparation techniques have been reported for the determination of pesticide residues in foodstuffs, in order to monitor pesticides at trace level in complex food matrices. Sample preparation involves both extraction and cleanup procedures which are essential. These include liquid–liquid extraction (LLE) (Rissatoz et al. 2007), solid-phase extraction (SPE) (Di Muccio et al. 2006), accelerated solvent extraction (ASE) (Muñoz et al. 2012), microwave-assisted extraction (MAE) (Papadakis et al. 2006), matrix solid-phase dispersion (MSPD) (Vazquez-Quintal et al. 2012), and solid-phase microextraction (SPME) (Menezes Filho et al. 2010). However, due to the complexity of analytes and matrices involved, most of the aforementioned sample preparation techniques for the determination of pesticide residues in food are rather complicated, and the recoveries of analytes are relatively low (SPME). Some of them are laborintensive and very expensive (SPE) and consume a large volume of solvent (LLE) (Beyer and Biziuk 2008). Resins contain especially large amounts of essential oils, compounds of low polarity (terpenes), and organic acids (Paraschos et al. 2007, Mastic growers association). Chios mastic gum is a resinous substance with a low-moisture content (
