Different extraction approaches for the biomonitoring of pesticides in pine needles

An ultrasonic extraction (USE) procedure followed by two alternative clean-up approaches using solid-phase extraction (SPE) cartridges (ENVI 18 and Florisil) and QuEChERS extraction and clean-up methodology were tested and compared for the determination of20 pesticides in Pinus pinea needles. The analysis and quantification were performed by gas chromatography-mass spectrometry (GC-MS) in selected ion storage (SIS) mode, using triphenyl phosphate (TPP) as the internal standard. One sample mass (5 g) and two pesticide spiking levels (20 and 100 ng g(-1)) were used in the validation assays. The limits of detection (LODs) were lower than 15.96 ng g(-1) for ENVI 18, 11.36 ng g(-1) for Florisil and 16.67 ng g(-1) for QuEChERS. Florisil yielded higher coefficients of variation for replicated analysis as did QuEChERS for the intermediate precision. To test pine needles' capacity as biomonitors for these pesticides, naturally contaminated needle samples were analyzed. With a 34% overall detection rate, concentrations ranged from 0.10 to 17.73 ng g(-1) (dry weight). USE + ENVI 18 and USE + Florisil were overall the best options for pesticide assessment in pine needles.