Determination of Twenty Organophosphorus Pesticides in Wheat Samples from Different Regions of Iran

Iranian Journal of Toxicology Volume 11, No 5, September-October2017 Original Article Determination of Twenty Organophosphorus Pesticides in Wheat Samples from Different Regions of Iran Attaollah Shakoori *1, Peyman Mahasti 2, Vahideh Moradi 2 Received: 10.01.2017 Accepted: 15.02.2017 ABSTRACT Background: Organophosphorus pesticides are widely used in agriculture, homes, gardens, and veterinary practices. Extensive application of pesticides in agriculture often results in residues of these compounds being absorbed into the foods, including wheat. The aim of this study was to evaluate the residue levels of 20 organophosphorus pesticides in wheat samples collected from different regions of Iran. Methods: This research reports a rapid, specific and sensitive multiresidue method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with mass spectrometric detection in the selected ion monitoring mode (GC– SIM–MS) to evaluate 20 organophosphorus pesticides in wheat samples. Results: In the concentration range of 20-200 ng/g, the calibration curves for each analyte was linear with a determination coefficient (R2) of 0.993 to 0.999. The limits of detection (LODs) and quantitation (LOQs) were between 2.5-6.7 and 7.5-20 ng/g, respectively. The mean recoveries obtained for three fortification levels (25, 50 and 100 ng/g, five replicates each) were 80-114% with a satisfactory precision (RSD<20%). 31.1% samples contained residues of one or more target compounds. Chlorpyrifos was the most common residue (17.8%), followed by pirimiphos-methyl (6.7%), diazinon (4.4%), chlorpyrifos-methyl (1.1%) and malathion (1.1%). Conclusion: Among the detected pesticides, only diazinon and malathion are permitted pesticides for wheat production in Iran. However, their concentrations were below the maximum residue levels (MRLs) established by the Iranian National Standard Organization (INSO). Keywords: GC-MS, Organophosphates, Pesticides, Wheat. IJT 2017 (5): 37-44 INTRODUCTION Pesticides are natural or synthetic chemicals used in agriculture to protect crops against destructive pests. They are also used in public health for the eradication of disease vectors and other pests. Annually, at least 4 million tons of pesticides are used for control of pests in the world. Only 1% of applied pesticides reach the target pests. Therefore, 99% of pesticides are left in the environment; finally affect living organisms [1]. Due to their widespread use, pesticides have now become a major group of environmental contaminants. They pollute the environment and remain in food chains, thereby posing health hazards to humans [2, 3]. Chemically, pesticides belong to different classes and organophosphorus pesticides constitute one of the major families, highly potent compounds used mainly as insecticides. Former restrictions on some persistent pesticides had led to the use of nonpersistent alternatives such as organophosphorus compounds, carbamates and pyrethroids, which are very effective in pest control, in both agricultural and residential settings [4]. Today, organophosphates are the most widely used pesticides across the world comprising 70% of the compounds in use [5]. In 2007, nearly 35% of applied insecticides in the US comprised organophosphorus, worth about 33 million pounds each year [6]. Intensive and extensive use of these compounds is now posing a significant risk to public health because of their potential adverse effects. Exposure to organophosphates affects not only those who use them occupationally, but the 1. PhD and Pharm D, Food Safety Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2. Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran. * Corresponding author: Email: Iranian Journal of Toxicology Attaollah Shakoori et al general population exposed to low concentrations of these compounds via foodstuffs and the environment throughout their lifetime [7]. Organophosphate poisoning continues to be a major cause of morbidity and mortality in third world countries. Chemically, organophosphates are esters of phosphoric or thiophosphoric acids. They can phosphorylate the active site of acetylcholinesterase (AChE), which hydrolyses acetylcholine (ACh) in cholinergic synapses and in neuromuscular junctions. This excessive accumulation of acetylcholine in synapses leads to activation of cholinergic receptors [8]. Acute effects of organophosphorus pesticides are well documented. They can cause dizziness, headaches, gastrointestinal distresses, bronchospasm, miosis, urination, sweating, lacrimation, bradycardia, fasciculations, muscle weakness, hypertension, liver and kidney damage, coma and ultimately death [9, 10]. However, some investigations have revealed a number of organophosphorus secondary targets not associated with the cholinergic system and may lead to immunotoxicity [11], endocrine disruption, genotoxicity, and potential carcinogenic effects such as non-Hodgkin’s lymphoma [12] and some types of leukaemia [13]. Children may be more vulnerable than adults may to the effects of pesticides because of proportionally higher food and water intake relative to body weight, along with immaturity in the neurological development and detoxification pathways [14]. Unlike acute poisoning, chronic exposure of humans to small amounts of organophosphates through the air and consumption of contaminated food and water can affect a large proportion of the population. Therefore, a pesticide residue in foodstuffs continues to be the target of many studies due to the mentioned adverse effects. Several techniques are available for the determination of these residues, but traditional pesticide analysis procedures are complicated, time-consuming and labor-intensive. In spite of the variety and complications of the matrices and low levels of pesticides in different food samples, analysis and sample preparation techniques in the area of pesticide residues have remarkably progressed [15]. In 2003, a fast and easy multiresidue technique was developed named QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method [16]. It is based on initial single-phase extraction with acetonitrile, followed by liquid–liquid partitioning by addition of anhydrous magnesium sulfate (MgSO4) and sodium chloride. Removal of the water content and cleanup are achieved by MgSO4 and a primary secondary amine (PSA) sorbent. This method is very flexible and serves as a template for determination of pesticide residues. Today, combination of QuEChERS method and mass spectrometry technique including LC-MS and GC-MS, have been successfully applied to determine the multiresidue levels of pesticides in various food samples [17,18]. Wheat is one of the most common staple foods in the world and especially in Iran. Most pesticide residues in wheat are due to direct application of pesticide duri (...truncated)