Determination of Triazole Fungicides in Liquid Samples Using Ultrasound-Assisted Emulsification Microextraction with Sol
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Determination of Triazole Fungicides in Liquid Samples Using Ultrasound-Assisted Emulsification Microextraction with Solidification of Floating Organic Droplet Followed by High-Performance Liquid Chromatography Ane Bordagaray & Rosa Garcia-Arrona & Esmeralda Millán
Received: 30 August 2013 / Accepted: 29 September 2013 / Published online: 12 October 2013 # Springer Science+Business Media New York 2013
A b s t r ac t An ul tra sou nd -a ss ist e d e m u l s i f i c a t i o n microextraction with solidification of organic droplet method followed by high-performance liquid chromatography with diode array detection for six triazole fungicide determination (diniconazole, fluquinconazole, flusilazole, myclobutanil, tebuconazole, and tetraconazole) was developed. After some preliminary experiments, undecanol was chosen as extracting solvent using 50 μL for 10 mL of liquid sample. A central composite design was performed to obtain the best experimental conditions for the following variables NaCl concentration (250 g L−1), extraction time (18 min), and temperature (30 °C) in ultrasonic bath. After the ultrasound-assisted extraction, two steps considering centrifugation (4,200 rpm, 10 min) and solidification (5 min, 3 °C) were done. Following these conditions, the method showed linearity higher than 0.9930 with the concentration ranged from 20 to 890 μg L−1. The limits of detection obtained using calibration curves were from 10.9 to 17.2 μg L−1 and the intra- and interday repeatability at two levels showed RSD values between 1.9 and 10.6 %. The enrichment factors for the studied triazoles were between 226 (flusilazole) and 255 (tebuconazole). Recovery studies at two spiked levels in apple and grape juices gave values from 64 to 112 %.
Keywords Triazole fungicides . Ultrasound-assisted emulsification microextraction . Solidification of floating
A. Bordagaray : R. Garcia-Arrona : E. Millán (*) Departamento de Química Aplicada, Facultad de Química, University of the Basque Country, Apdo. 1072, 20080 San Sebastian, Spain e-mail: [email protected]
organic droplet . Fruit juice . Central composite design . High-performance liquid chromatography
Introduction Triazole fungicides are systemic pesticides widely used to control fungus diseases in field crops. These triazole compounds inhibit ergosterol biosynthesis needed for membrane structure and function (Tomlin 2000). The widespread use of triazoles has increased the concern about the detrimental effects in ecosystems and human health. Some toxicological studies in rats have shown tumorigenic (Wolf et al. 2006) and endocrine disrupting (Goetz et al. 2007) effects. Since the fungicide residues have been found on food for human consumption, the accurate determination of the residue levels is necessary for food safety monitoring and regulatory purposes. In order to protect the health of consumers, maximum residue levels (MRLs) in raw products have been established. European Union has fixed MRLs ranging from 0.01 to 2 mg kg −1 in apples and grapes for diniconazole, fluquincon
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