Determination of Picoxystrobin Residues in Watermelon Field Trials by Rapid Resolution Liquid Chromatography Triple Quadrupole Mass Spectrometry: Dissipation Kinetics and Terminal Residues

Abstract

A simple, rapid and efficient method for the determination of picoxystrobin in watermelon ecosystem was established and validated via QuEChERS (quick, easy cheap, effective, rugged and safe) method using rapid resolution liquid chromatography tandem mass spectrometry (RRLC-MS/MS). The average recoveries (n=5) of picoxystrobin in three matrix at three fortification levels ranged from 89.4% to 102.6%. The limits of detection (LODs) were lower than 1.28×10 _ 4 mg L _ 1. The limits of quantification (LOQs) were 0.001 mg kg _ 1 for watermelon flesh (whole watermelon) and 0.005 mg kg _ 1 for soil. The half-life of picoxystrobin of whole watermelon (soil) in Shandong and Anhui were 1.43 (4.18) days and 3.71 (17.32) days, respectively. The picoxystrobin terminal residues in watermelon were lower than 0.001 mg kg _ 1 under the recommended dosages, which were far below the maximum residue limit (MRL) set by China (0.05 mg kg _ 1). These obtained data not only provide scientific information about safety estimation of picoxystrobin in watermelon and the kinetics of dissipation, but also facilitate trade exportation of watermelon for China.

Residue dissipation, transfer and safety evaluation of picoxystrobin during tea growing and brewing

“…For example, the t 1/2 of picoxystrobin were 10.3, 12.9 and 14.9 days in soil at Shandong, Tianjin and Jiangsu, respectively 14 ; the t 1/2 of picoxystrobin were 3.6, 1.5 and 8.6 days in soil at Hebei, Hubei and Shandong, respectively 18 ; the t 1/2 of picoxystrobin in photocatalytic degradation were 26.7, 32.8, 12.8 and 3.20 h on the surface of fluvo‐aquic soil, cinnamon soil, red soil and water, respectively, and the migration of picoxystrobin were 0.083, 0.08 and 0.25 in fluvo‐aquic soil, cinnamon soil and red soil, respectively 28 ; the t 1/2 of picoxystrobin ranged from 2.2 to 10.7 days in grapery soil 15 ; the t 1/2 of picoxystrobin was 11.6 days in open field soil and 23.1 days in plastic house soil 30 . And the t 1/2 of picoxystrobin were 4.18 and 17.32 days in soil at Shandong and Anhui, respectively 31 . Thus, the different dissipation rates of picoxystrobin maybe related to climates and soil types in different regions.…”

“…The dissipation of picoxystrobin has been investigated in other plants. For example, the t 1/2 of picoxystrobin were 2.70, 5.71 and 9.76 days for cucumber at Shandong, Tianjin and Jiangsu, respectively 14 ; the t 1/2 of picoxystrobin were 2.4, 2.8 and 2.1 days for peanut seedling at Hebei, Hubei and Shandong, respectively, and a pre‐harvest interval of 14 days was recommended for the safe use of picoxystrobin in peanut crop 18 ; the t 1/2 of picoxystrobin for grapefruit range from 5.9 to 12.6 days 15 ; the t 1/2 of picoxystrobin for whole watermelon were 1.43 and 3.71 days at Shandong and Anhui, respectively 31 . Thus, the different dissipation rates of picoxystrobin may be related to the growth dilution of tea and other plants, and differences in climate between different regions.…”

“…In recent years, residue analyses of picoxystrobin in different matrices have gradually increased. There have been many researches concerned with the environmental behaviors of picoxystrobin in different fruits and vegetables, such as watermelon, 13 cucumber, 14 grape, 15 pepper, 16 wheat 17 and peanut, 18 and also in water 19 and soil 14 ; analytical methods have been developed for picoxystrobin residue determination in various matrices, including vegetables, 16, 20–23 fruits, 13, 20, 21 baby foods, 24 soil, 13, 16, 25 irrigation water, 19 wheat 17 and Dendrobium officinale Kimura et Migo, 27 by gas chromatography with nitrogen–phosphorus and electron capture detection, 13, 14, 26, 27 high‐performance liquid chromatography (HPLC), 17, 22, 28 gas chromatography–mass spectrometry 19, 20, 24 and ultra‐performance liquid chromatography (UPLC)–mass spectrometry 15, 16, 18, 20, 21, 23, 25, 29–31 . Most of the limits of quantitation (LOQs) of these methods were from 0.005 to 0.05 mg kg −1 .…”