Simultaneous determination of difenoconazole, trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon under field conditions by GC–MS/MS

Abstract

An optimized quick, easy, cheap, effective, rugged and safe method for the simultaneous determination of difenoconazole, trifloxystrobin and its metabolite trifloxystrobin acid residues in watermelon and soil was developed and validated by gas chromatography with tandem mass spectrometry. The samples were extracted with acetonitrile (1% formic acid) and cleaned up by dispersive solid-phase extraction with octadecylsilane sorbent. The limit of quantification of the method was 0.01 mg/kg, and the limit of detection was 0.003 mg/kg for all three analytes. The recoveries of the fungicides in watermelon, pulp and soil were 72.32-99.20% for difenoconazole, 74.68-87.72% for trifloxystrobin and 78.59-92.66% for trifloxystrobin acid with relative standard deviations of 1.34-14.04%. The dissipation dynamics of difenoconazole and trifloxystrobin in watermelon and soil followed the first-order kinetics with half-lives of 3.2-8.8 days in both locations. The final residue levels of difenoconazole and trifloxystrobin were below 0.1 mg/kg (maximum residue level [MRL] set by China) and 0.2 mg/kg (MRL set by European Union), respectively, in pulp samples collected 14 days after the last application. These results could help Chinese authorities to establish MRL of trifloxystrobin in watermelon and provide guidance for the safe and proper application of both fungicides on watermelon.

Dissipation, residues and risk assessment of spirotetramat and its four metabolites in citrus and soil under field conditions by LC‐MS/MS

“…Matrix effects, in terms of signal suppression or enhancement, could have affected the response in a positive or negative manner (Zhang et al, ). The matrix‐induced signal suppression/enhancement was calculated by comparing the slope of the matrix‐matched calibration curve with that of a pure solvent calibration curve (Z. R. Li, Zhao, et al, ; Kang et al, ). Five replicate spiked samples (citrus pulp, citrus peel, whole citrus and soil) under three different concentrations of mixed standard solutions were extracted, purified and analyzed, as described above.…”

Otimização de método analítico para estudo da degradação do difenoconazol em substrato com adição de lodo ativado do esgoto doméstico tratado

“…Vaso contendo 500 g de solo em BS com adição de 20 mg kg -1 . VSD Para determinar o perfil de degradação do pesticida no solo com adição de LET foi seguido o método experimental utilizado por Kang et al (2017) que consiste na coleta de amostras aleatórias a partir de 2 h (considerada como a concentração inicial), 1,2,3,5,7,10, 14 e 21 dias após a aplicação de pesticida. Todos vasos foram cuidadosamente homogeneizados anteriormente a cada coleta e as amostras foram retiradas (em triplicata) para extração, clean up e análise em CGEM.…”

“…Um dos triazóis mais comuns no mercado como fungicida agrícola é o difenoconazol (DFC), que se caracteriza como fungicida por interferir na biossíntese do ergosterol e inibir a desmetilação de esteroides comprometendo o crescimento dos fungos (KANG et al, 2017;SZPYRKA et al, 2016). Aplicado em diversas culturas, o DFC (cis, trans-3-cloro-4-[4-metil-…”

Facile synthesis of magnetic zinc metal‐organic framework for extraction of nitrogen‐containing heterocyclic fungicides from lettuce vegetable samples

“…Recently, several analytical methods have emerged as the promising techniques to detect nitrogen‐containing heterocyclic fungicides, including HPLC , LC–MS/MS , GC , and GC–MS . However, these detection methods suffer greatly from matrix interferences within the complex sample matrix, often resulting in false positives .…”