Dissipation Pattern of Quinalphos in Cauliflower, Tomato and Bean Samples
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J Consum Prot Food Saf (2018) 13:63–67 Journal of Consumer Protection and Food Safety https://doi.org/10.1007/s00003-017-1143-8 Journal fu¨ r Verbraucherschutz und Lebensmittelsicherheit RESEARCH ARTICLE Dissipation pattern of quinalphos in cauliflower, tomato and bean samples 1 1 1 Zerin Sultana Munia • Mohammad Shoeb • M. I. R. Mamun • Nilufar Nahar1 Received: 17 June 2017 / Accepted: 13 November 2017 / Published online: 24 November 2017 Ó Bundesamt fu¨r Verbraucherschutz und Lebensmittelsicherheit (BVL) 2017 Abstract Quinalphos, an organothiophosphate 0.50 lgg-1 in cauliflower, tomato and bean) value chemical, is chiefly used as an insecticide. A field within 6, 4 and 7 days after application, respectively. experiment was conducted at Bangladesh Agricul- tural Research Institute (BARI), to study the Keywords Bean Á Cauliflower Á Dissipation Á dissipation of quinalphos in tomato, cauliflower and Quinalphos Á GC-ECD Á Tomato bean samples when sprayed at its recommended dose and were collected from 0 (2 h after application) 1 Introduction to 15 successive days. To determine the residual value of quinalphos, the samples were extracted in quick, Vegetables are healthy foods that are low in fat, high easy, cheap, effective, rugged, and safe (QuEChERS) in dietary fibres and containing various minerals, method and run through a gas chromatography- vitamin C etc. Today, vegetables are available in electron capture detector (GC-ECD). Higher, middle Bangladesh throughout the year, but especially are and lower concentration calibration curves were plentiful during winter and spring. However, as obtained with linear correlation coefficient (r2)of farmers try to increase yields they frequently use 0.998, 0.995 and 0.993, respectively. Limit of detec- pesticides during vegetable cultivation, sometimes tion (LOD) and limit of quantification (LOQ) were more than the recommended pesticide use in veg- found to be 0.009 and 0.027 lgmL-1, respectively. etables, which is becoming a consumer food safety The percentages of the recovery of quinalphos resi- concern (Nahar et al. 2012, 2016). In Bangladesh, dues in spiked vegetable samples at three different 50–70% of vegetables on the market are contami- levels (0.625, 2.5 and 5.0 lgmL-1) were in the range nated by residues of toxic pesticides (Karanth 2000), of 74–86%. The amount of quinalphos residue in mainly due to harvesting the crops before the safe tomato, bean and cauliflower were in the range of waiting period. -1 0.05–6.3, 0.05–3.1 and 0.06–6.5 lgg and dissipated Quinalphos, C12H15N2O3PS, (O,O-diethyl-O-(quinox- below maximum residue limit (MRL; 0.20, 0.20 and alin-2yl), is an organothiophosphate pesticide, which is widely used to control pests in vegetables (Suvard- han et al. 2005). It is solid at low temperature (melting point 31.5 °C) and is very toxic to mammals -1 Electronic supplementary material The online version of (LD50 = 71 mg kg ) (Anonymous 2011). It is mainly this article (https://doi.org/10.1007/s00003-017-1143-8) contains used for the management of Diamond-Back Moth supplementary material, which is available to authorized users. (DBM) (Plutella xylostella) on vegetables and Tobacco Caterpillar (Manduca sexta) on tobacco. The recom- & Mohammad Shoeb mended dose is 500 g a.i. ha-1 on cabbage [email protected] (Anonymous 2009) and could control 100% DBM on 1 Department of Chemistry, University of Dhaka, Dhaka cauliflower (Ramzan and Singh 1980). It is also a good 1000, Bangladesh 123 64 Z. S. Munia et al. controller of eggplant fruit and shoot borer (Leucin- The extraction process followed the quick, easy, odes orbonalis) (Gupta and Kauntey 2007). However, cheap, effective, rugged, and safe (QuEChERS) using excess of quinalphos can pose human health method of Anastassiades et al. (2003). To the hazards both to farmers and consumers (Banerjee homogenized sample (10 g) in a Teflon test tube ethyl et al. 2006). Due to its high toxicity, it has been acetate (20 mL) was added. The tube was vortexed for banned in many countries. 1 min, after which 6 g MgSO4 and 1.5 g NaCl were Quinalphos is not an approved pesticide in Ban- added and then again vortexed for 1 min. The mix- gladesh. Despite of not being registered, it is ture was then centrifuged for 5 min at 5.000 rpm frequently found in Bangladeshi produce. Therefore, maintaining temperature 20 °C (SIGMA 2-16 Bench- it is necessary to determine the fate of quinalphos in top, 10,000 rpm). Of the supernatant, 10 mL was Bangladeshi crops under the climatic and soil prop- transferred into a round bottom flask and the solvent erties of Bangladesh. Such information is important was reduced to dryness using rotary evaporator for decisions regarding legislation on the use of this (Bu¨chi R-210, Switzerland). n-Hexane (5 mL) was pesticide in Bangladesh, whether it should be regis- added to the dried mass and from there 2 mL solu- tered for use or if stricter actions should be taken to tion was transferred into a screw cap test tube. remove it from the market. The objective of this study For clean-up, 150 mg primary secondary amine was the dissipation pattern of quinalphos on tomato, (PSA) and 750 mg MgSO4 were added and the test bean and cauliflower under the condition of Ban- tube vortexed for about 1 min. It was then cen- gladeshi agriculture, ultimately to collect trifuged for another 5 min. and then the extract was information on the possible safe harvesting period passed through pipette with cotton plugged inside before produce can be admitted onto the local which was washed successively with methanol, ace- market. tone and finally with n-hexane. Quinalphos residues were identified and quanti- fied using a Shimadzu 17A gas chromatograph (GC) 2 Materials and methods equipped with an electron capture detector (ECD). Separation was on an ultra-performance quartz cap- The standards of quinalphos (99% pure) were pur- illary column (HP 5MS, 30 m, 250 lm internal chased from Dr. Ehrenstorfer, Germany. Primary diameter, 0.25 lm film thickness). The injector and secondary amine (PSA) from Supelco USA, was used in detector temperatures were set to 280 and 300 °C, clean-up steps. Analytical grade magnesium sul- respectively, and the column temperature was pro- phate, sodium chloride (anhydrous), ethyl acetate grammed from 165 °C as initial temperature, held for and ultra-pure GC-grade n-hexane were obtained 2 min, raised at 15 °C min-1 to 255 °C, which was from Merck KGaA, Germany. held for 4.0 min. Nitrogen gas was used as carrier Seeds of bean (Phaseolus vulgaris), tomato (Lycop- and make up gas, and the flow rate was 1 mL min-1. ersicon lycopersicum) and cauliflower (Brassica Samples were injected manually in the splitless oleracea var. botrytis) were sown in a nursery bed at (1 min)/split mode. the research fields of the Entomology Division, The recovery experiments of quinalphos in spiked Bangladesh Agricultural Research Institute (BARI), control vegetable samples were carried out in three Gazipur, Bangladesh. Quinalphos, 0.03 percent different concentrations levels, 0.625, 2.5 and aqueous emulsion prepared from Convoy 25 EC was 5.0 lgmL-1 and were extracted and cleaned up fol- sprayed at a recommended dose (1 mL L-1 of water lowing the same procedure as described above. ha-1). Three replicate samples from each bed of three vegetables were collected from day 0 (2 h after spraying) and gradually each day up to 15 days 3 Results and discussion after spraying. Before spraying, control samples (untreated) were harvested. All the samples were The residual level of quinalphos in tomato, bean and immediately brought to the laboratory and kept in a cauliflower was analysed by GC-ECD using external freezer below -20 °C. The collected samples of each standard calibration method. The recovery percent- day were cut into small pieces and then homoge- age of quinalphos at 0.625, 2.5 and 5.0 lgmL-1 nized by kitchen blender; the required amount of fortification levels was 85, 74 and 86%, with relative homogenized samples was transferred into Teflon standard deviation (RSD) of 6.2, 4.2 and 5.5%, tube and then preserved in the freezer until respectively, (Table 1) which is within accept- analysis. able range (Codex 2010). The calibration curves 123 Dissipation pattern of quinalphos in cauliflower, tomato and bean samples 65 Table 1 Linearity range, correlation coefficients (r2), LOD, LOQ, Percent recovery, ± SD and percent RSD of quinalphos Calibration Linearity range Correlation coefficient LOD (lg LOQ Spiking level % ± SD % curve (lgmL-1) (r2) mL1) (lgmL1) (lgmL1) Recovery RSD Higher conc. 2.5–6.5 0.998 0.009 0.027 0.625 85 5.3 6.2 Middle conc. 1.0–2.5 0.995 2.5 74 3.1 4.2 Lower conc. 0.06–0.13 0.993 5.0 86 4.7 5.5 showed excellent linear coefficients (r2) of 0.998, were below the detection limit after 10, 11, 11 days 0.995 and 0.993 for higher, medium and lower con- cauliflower, tomato and bean, respectively. The centration calibration curves, respectively, and the maximum residue limit (MRL) of quinalphos in linearity ranges were 2.5–6.5, 1.0–2.5 and tomato, bean and cauliflower are 0.20, 0.50, 0.20 lg/ 0.06–0.13 lgmL-1, respectively (Fig. S1). LOD and LOQ g, respectively (EPA 2011). In our study the quinalphos of quinalphos in tomato, bean and cauliflower were residue dissipated to below the MRL within 4, 7 and 0.009 and 0.027 lgmL-1, respectively. The unwanted 6 days after application on/in cauliflower, tomato and interfering compounds with quinalphos were and bean, respectively.