Development and application of a screening method for triazole fungicide determination in liquid and fruit samples using solid-phase microextraction and HPLC-DAD

A screening method for determination of six triazole fungicides (diniconazole, fluquinconazole, flusilazole, myclobutanil, tebuconazole and tetraconazole) using the solid-phase microextraction (SPME) technique coupled to a high-performance liquid chromatography-diode array detector (HPLC-DAD) was developed. Experimental variables were chosen and their values were fixed according to an experimental design with the steps of screening (2(5-1) fractional factorial design) and optimization of the significant variables (central composite design). Using polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers, the other experimental conditions were: extraction time, 90 min; extraction temperature, 60 degrees C; NaCl addition, 180 g L-1; static desorption mode and desorption time, 2 min. The method showed good inter and intraday precision (RSD values less than 13.2%) and the limits of detection were from 1.5 to 5.9 mg L-1 in liquid extracts and from 0.08 to 0.3 mg kg(-1) in solid products. The method was applied to grape and apple fruit samples previously sprayed with commercial products containing the analytes. Samples were taken from peel, pulp and juice following a pre-harvest interval of two weeks. Also, rain samples under the fruit trees were collected. Myclobutanil and tebuconazole were found in the peel and rain, but not in pulp and juice samples.