Determination of Etoxazole Residues in Fruits and Vegetables by SPE Clean

This article was downloaded by: [Enstinet], [Farag Malhat] On: 25 February 2013, At: 03:14 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/lesb20 Determination of etoxazole residues in fruits and vegetables by SPE clean-up and HPLC-DAD Farag Malhat a , Hany Badawy b , Dalia Barakat b & Ayman Saber a a Pesticide Residues and Environmental Pollution Department, Agriculture Research Center, Dokki, Giza, Egypt b Pesticides & Economic Insect Department, Faculty of Agriculture, Cairo University, Cairo, Egypt To cite this article: Farag Malhat , Hany Badawy , Dalia Barakat & Ayman Saber (2013): Determination of etoxazole residues in fruits and vegetables by SPE clean-up and HPLC-DAD, Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes, 48:5, 331-335 To link to this article: http://dx.doi.org/10.1080/03601234.2013.742371 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions This article may be used for research, teaching, and private study purposes. 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Journal of Environmental Science and Health, Part B (2013) 48, 331–335 Copyright C Taylor & Francis Group, LLC ISSN: 0360-1234 (Print); 1532-4109 (Online) DOI: 10.1080/03601234.2013.742371 Determination of etoxazole residues in fruits and vegetables by SPE clean-up and HPLC-DAD FARAG MALHAT1, HANY BADAWY2, DALIA BARAKAT2 and AYMAN SABER1 1Pesticide Residues and Environmental Pollution Department, Agriculture Research Center, Dokki, Giza Egypt 2Pesticides & Economic Insect Department, Faculty of Agriculture, Cairo University, Cairo, Egypt A method for determination of etoxazole residues in apples, strawberries and green beans was developed and validated. The analyte was extracted with acetonitrile from foodstuff and a charcoal-celite cartridge was used for clean-up of raw extracts. Reversed phase high performance liquid chromatography with photodiode array detector (HPLC-DAD) was used for the determination and quantification of etoxazole residues in the studied samples. The calibration graphs of etoxazole in a solvent or three blank matrixes were linear within the tested intervals 0.01–2 mg L−1, with correlation coefficient of determination >0.999. The combined solid phase extraction (SPE) clean-up and the chromatographic method steps were sensitive and reliable for simultaneous determination of etoxazole residues in the studied samples. The average recoveries of etoxazole in the tested foodstuffs were between 93.4 to 102% at spiking levels of 0.01, 0.10, and 0.50 mg kg−1, with relative standard deviations ranging from 2.8 to 4.7%, in agreement with directives for method validation in residue analyses. The limit of detection (LOD) of the HPLC-DAD system was 100 pg. The limit of quantification of the entire method was 0.01 mg kg−1. Keywords: Etoxazole in food stuff, solid phase extraction, HPLC-DAD. Introduction headaches to chronic diseases like cancer and endocrine dis- ruption, pesticide residues in food products must be closely Etoxazole (2-(2, 6-difluorophenyl)-4-[4-(1, 1-dimethyleth- monitored and strictly controlled.[5–7] In order to ensure yl)-2-ethoxyphenyl]-4, 5-dihydrooxazole), a new organo- the safety of consumable food products and supervise in- fluorine pesticide was produced by Sumitomo Chemical ternational trade, governmental authorities of each country Co. Ltd (Osaka, Japan) in 1998 and was developed world- and international organizations have established maximum wide as a new-generation acaricide for citrus, apples, grapes, residue limits (MRLs) to regulate pesticide concentration vegetables, flowers, cotton and tea.[1] Etoxazole is an alter- in food products.[8,9] native for carbamates, organochlorines and other miticides, Analytical methods that are used to monitor pesticide and works by inhibiting molting.[2,3] Main pests targeted by levels in food should be capable of measuring pesticide Downloaded by [Enstinet], [Farag Malhat] at 03:14 25 February 2013 etoxazole are tetranychid spider mites such as Panonychus residues at very low levels.[10] In addition, these methods ssp. and Tetranychus ssp. Insecticidal side effects on aphids, should be able to identify and quantity the types of pesti- green rice leafhoppers and diamondback moths have also cides found in food products.[11] Furthermore, these meth- been claimed but are of lesser importance. Etoxazole is ac- ods should be fast, robust and simple in order to minimize tive against eggs, larvae and nymphs of spider mites but the requirements for training and the time spent on sam- lacks any efficacy against male and female adults.[4] It usu- pling and maintaining equipment.[12] Although etoxazole ally exhibits high efficacy and behaves like an insect/mite has been marketed in Egypt for about 10 years, to our growth regulator, considering its effects on the different knowledge no residue data in food samples have been re- developmental stages mentioned above. ported. Studies of etoxazole focus on toxicology, mode of Since pesticides are known to cause several human health action, and efficacy.[13,14] In contrast, the papers on analyt- problems, which range from short-term sickness such as ical methods for residues of etoxazole in food stuffs seem to be rare.[15,16] The aim of this study is to develop an analytical method Address correspondence to Farag Malhat, Pesticide Residues and Environmental Pollution Department, Central Agricultural Pes- using solid phase extraction (SPE) and high performance ticide Laboratory, Agriculture Research Center, Dokki, Giza, liquid chromatography with photodiode array detector Egypt; E-mail: farag [email protected] (HPLC-DAD) to determine etoxazole residues in fruits and Received July 9, 2012. vegetables. 332 Malhat et al. Materials and methods sodium chloride was added, the mixture was vortexed for another 2 min, and the extract was centrifuged (4000 rpm) Equipment for 10 min. An amount measuring 5 mL of the clear upper acetonitrile was transferred to a spherical flask and evapo- The HPLC system was an Agilent 1100 series (Agilent ◦ rated to dryness by using a rotary evaporator at 40 C. The Technologies, Wilmington, DE) equipped with an analyt- residue in the flask was reconstituted in a 2 mL solvent ical column (150 × 4.6 mm id, 5 µm ODS) attached to (n-hexane: acetone = 97:3, v/v). a photodiode array detector. The food processor was a The chromatographic cartridge used for clean-up was Thermomix, Vorwerk. For water purification, a Millipore- packed from bottom to top with (1) absorbent cotton, Q system was used. The vortex shaker and high-speed cen- (2) 1 cm of anhydrous sodium sulphate, (3) 1 g of charcoal- trifuge were made in Germany.The rotary evaporator was a celite chromatographic mixture (1 + 20, w/w), and (4) 1 cm Buchi. of anhydrous sodium sulphate. The packed column was pre- conditioned with a 5 ml solvent (n-hexane: acetone = 97:3, Reagents v/v). The redissolved extract was applied to the cartridge. Acetone, n-hexane, acetonitrile and methanol were sup- Etoxazole was eluted from the cartridge with a 15 mL (n- plied by Merck (Darmstadt, Germany) in HPLC grade hexane: acetone = 97:3, v/v). The elute obtained was col- quality. Anhydrous sodium sulphate and sodium chloride lected in a spherical flask and then evaporated to dryness. (made in Egypt) were baked at 130◦C for 8 h. Charcoal- The residue was redissolved with 1 mL acetonitrile, and fi- celite chromatographic mixture, one part (by weight) char- nally filtered by a 0.45 µm filter membrane for LC analysis. coal decolorizing powder, neutral, BDH, is combined with twenty parts celite 545 diatomaceous earth, mixed well and ◦ baked at 130 C over night. Prior to actual uses in a column, Chromatographic conditions it was cooled in a dessicator. Ultra pure water was prepared by the Millipore system. The neat standard of etoxazole The chromatographic conditions used for the analysis of (purity ≥98%) was supplied by Sumitomo Chemical Com- etoxazole residues were as follows: an Agilent 1100 liq- −1 uid chromatograph was used and equipped with a DAD. pany. A stock standard solution (100 mg L ) was prepared × in acetonitrile and stored at −18◦C. A hypercell ODS analytical column (150 mm 4.6 mm id, 5 µm) was used. The mobile phase was acetonitrile- + + Method development methanol-water (45 40 15, v/v/v) with a flow rate of 0.8 mL/min. The injection volume was 20 µL. Detection Samples. Apples, strawberries and green beans were pur- wavelength for etoxazole set at 240 nm. Under these con- chased from a local supermarket and those that had no ditions, the retention time of etoxazole was about 7.2 min. detectable residues were used as blank samples. Fruit and vegetable samples were comminuted by food processor and stored at −18◦C. Apple samples were also collected from an apple orchard Results and methods located at El-Hamol village, Menof province, El Menofiya governorate and treated, during June 2011, with Baroque Method validation SC (10%, etoxazole) at the recommended application rate Linearity.

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