Analysis of Strobilurin Fungicides, Neonicotinoid Insecticides and Degradation Products in Atmospheric Particles

Abstract

In this study, a liquid chromatography-tandem mass spectrometry method has been developed for the simultaneous detection of concentration of 8 neonicotinoid insecticides with 5 degradation products of neonicotinoid insecticides and 7 strobilurin fungicides in the particle phase of atmospheric samples. Detection limits ranged from 0.5 to 3 ng/mL and the recovery percent ranged between 83.5% to 108.3% with relative standard deviation <13% for all analytes. The sampling site was located in Omak, WA within the Okanogan County agricultural region where vineyards and apple orchards are the dominant crops. Matrix effect was determined to evaluate the performance of the developed sample clean-up procedure to remove the matrix. The determined matrix effect revealed that the highest exhibited matrix effects were for metabolites of neonicotinoids, while strobilurin fungicides showed soft to moderate matrix effects in >75% of samples. Neonicotinoids that were detected included imidacloprid, clothianidin, acetamiprid, and thiamethoxam. The highest detection frequency in 2016 was shown for imidacloprid (47%), while in 2018 acetamiprid had the highest detection frequency (67%). This is the first time that one of the neonicotinoid degradation products (desmethyl-thiamethoxam) was detected in the particle phase of air samples worldwide. For strobilurin fungicides, azoxystrobin, kresoxim methyl, trifloxystrobin, and pyraclostrobin were detected in the particle phase. The highest detection frequency was shown for pyraclostrobin (60% in 2016 and 78% in 2018) with the highest concentration (9.82 pg/m3 and 9.87 pg/m3 in 2016 and 2018, respectively).