Development of a Vortex-Assisted Dispersive Liquid-Liquid Microextraction (VA-DLLME) and LC-MS/MS Procedure for Simultan
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Development of a Vortex-Assisted Dispersive Liquid-Liquid Microextraction (VA-DLLME) and LC-MS/MS Procedure for Simultaneous Determination of Fipronil and its Metabolite Fipronil Sulfone in Tomato Fruits Osama I. Abdallah 1,2
&
Nevein S. Ahmed 1
Received: 13 February 2019 / Accepted: 10 June 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract A rapid, simple, inexpensive, and reliable vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) method was developed for the determination of fipronil and its major metabolite, fipronil sulfone, in tomato fruits using liquid chromatography tandem mass spectrometry (LC-MS/MS). No salting-out or cleanup steps were required after extraction. Average recoveries ranged from 89.8 to 96.3% with relative standard deviation (RSD) values below 11.6%. The limit of quantitation (LOQ) of the method was 0.25 μg/kg, which is 20 times below the European Union-defined maximum residue limit (MRL) of 5 μg/kg. Good linearity was achieved, with a correlation coefficient ≥ 0.996 based on matrix-matched calibration. We investigated the dissipation and residue distribution of fipronil in tomato fruits after one application of suspension concentrate (SC) or emulsifiable concentrate (EC) formulations over 28 days under field conditions using the VA-DLLME method. The half-life (t1/2) of fipronil dissipation was 2.4 and 2.8 days, and the estimated pre-harvest interval (PHI) was 23 and 32 days for the SC and EC formulation, respectively. A risk assessment was conducted by evaluating the health risk index (HRI); the estimated PHIs values indicate it is safe to consume tomatoes after the recommended application of fipronil. Keywords Fipronil . Tomatoes . DLLME . Method validation . Dissipation kinetic . Risk assessment
Introduction Tomato (Solanum lycopersicum L.), a plant belonging to the Solanaceae family, is one of the most important agricultural crops and is widely cultivated throughout the world (Dorais et al. 2008). Egypt is the third leading producer of tomatoes worldwide, producing approximately 7.3 million tonnes per year (Abd-Alrahman and Osama 2012; FAOSTAT 2018). Tomato fruits provide basic nutrition in the form of various biochemical compounds such as minerals, vitamins, carbohydrates, proteins, and antioxidant molecules. Several of these molecules have been shown to exert beneficial effects, such as
* Osama I. Abdallah [email protected]; [email protected] 1
Department of Pesticide Residues and Environmental Pollution, Central Agricultural Pesticide Laboratory, Agricultural Research Center, Giza 12618, Egypt
2
Food Safety Laboratory, Al-Qassim Municipality, Buraydah, Al-Qassim, Saudi Arabia
preventing diabetes, maintaining blood pressure, and promoting cardiovascular health (Elbadrawy and Sello 2016). A number of factors may decrease the productivity and quality of tomato crops, including poor-quality seeds, pests, and climatic conditions (Oerke 2006). Fipronil, 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]4-[(trifluoromethyl
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