Optimization of Solid-Phase Microextraction Procedure Coupled to GC-ECD for Triazole Fungicides Determination in Juice S
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Optimization of Solid-Phase Microextraction Procedure Coupled to GC-ECD for Triazole Fungicides Determination in Juice Samples Ane Bordagaray & Rosa Garcia-Arrona & Esmeralda Millán
Received: 8 July 2010 / Accepted: 27 September 2010 / Published online: 7 October 2010 # Springer Science+Business Media, LLC 2010
Abstract A solid-phase microextraction (SPME) procedure followed by gas chromatography electron capture detection (GC/ECD) for the determination of triazole residues was developed. An experimental design with two steps was done. Firstly, a 26−2 fractional factorial design for screening several experimental variables (fiber-coating type, extraction temperature, extraction time, stirring rate, desorption temperature, and desorption time) was done. After, a twofactor central composite design for optimizing, the experimental conditions were carried out. The chosen experimental conditions were: fiber, PDMS/DVB; extraction time, 45 min; extraction temperature, 60 °C; desorption time, 3 min; desorption temperature, 260 °C, and stirring speed, 500 rpm. Using those conditions the limits of detection obtained for tetraconazole, myclobutanil, and diniconazole were in the order of few μg L−1 in grape and apple liquid extracts. Recoveries were from 93.6% to 112.1%. Relative standard deviation ranged from 1.2% to 11.6% (apple) and 6.7 to 18.0% (grape). The method was applied to five grape samples and 13 apple samples collected in Navarra, Rioja, and Basque Country. Quantification was performed by the standard addition method. Three standard additions by duplicate covering adequate range concentration were used. Myclobutanil was found in three apple samples (110–122 μg L−1) and diniconazole in one grape sample (9.4 μg L−1). Keywords Experimental design . Azole fungicides . Apple . Wine . Solid- phase microextraction . GC/ECD A. Bordagaray : R. Garcia-Arrona : E. Millán (*) Departamento de Química Aplicada, Facultad de Química, University of the Basque Country, Apdo. 1072, 20080 San Sebastián, Spain e-mail: [email protected]
Introduction Triazole fungicides are one of the most common groups of pesticides applied to vineyards and apple orchards. Besides its antifungal activity, those compounds are also discussed as a group that disturbs endocrine activity in humans. Azole fungicides used in agriculture are moderately lipophilic and fairly persistent with typical half lives of weeks to months. They may reach the aquatic environment mainly by surface runoff and spray drift. Those chemicals can reach plant tissues leaving residues that can be detected in fruits and processed products. The determination of 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 0.1 to 2 mg kg−1 in apples and grapes for diniconazole, myclobutanil, tebuconazole, and tetraconazole (Regulation EC 396/2005). However, there is no legislation for processed products suc
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