Application of [U-¹⁴C-phenyl]-cyprodinil on spring wheat to investigate the formation and structure of non-extractable residues within the cell wall

Investigation on the Chemical Structure of Nonextractable Residues of the Fungicide Cyprodinil in Spring Wheat Using 13C-C1-Phenyl-Cyprodinil on 13C-Depleted Plants—An Alternative Approach to Investigate Nonextractable Residues

“…[19,21] Wheat seeds were germinated outside the growth chamber for 3 days, transferred to moistened vermiculite (Deutsche Vermiculite GmbH, Germany), and put into the growth chamber which was then closed. ''Horizont'') were cultivated for 9 weeks under a defined atmosphere containing 300 ppm 12 CO 2 with a residual 13 C-content of 0.05% (Chemotrade, Germany).…”

“…''Horizont'') were cultivated for 9 weeks under a defined atmosphere containing 300 ppm 12 CO 2 with a residual 13 C-content of 0.05% (Chemotrade, Germany). It was shown that the basipetal transport of foliar-applied cyprodinil was neglectable [21] ; thus vermiculite was used instead of a hydroponic system. Due to the CO 2 trap in the air-inlet, the maximum air supply was limited to 4 L/min, equivalent to an exchange of the chamber volume (500 L) every 2 h. This rate was sufficient to prevent accumulation of radioactivity resulting from application in the gas phase of the chamber, and to prevent CO 2 concentration to drop below 250 ppm.…”

“…[21] Reference compounds for TLC analyses were silylated similarly. [21] Reference compounds for TLC analyses were silylated similarly.…”

“…The 14 C-labelled residues formed during metabolism are then subjected to various extractional procedures to mobilize them for their subsequent characterization. [17,18] In previous studies, [19,21] it could be clearly shown that the main portions of cyrodinil's bound residues was located in the lignin, which is generally considered as not bioavailable. An investigation of chemical structures is only possible by spectroscopic methods, such as mass or liquid state NMR spectroscopy, both requiring mobilization of the residues preliminary to their analyses, and thus, rising equivalent problems as those encountered in classical 14 C-studies.…”

“…It acts by inhibition of the methionine biosynthesis of fungi. In a previous study published recently, [21] a complete mass balance at field application rate-simulating the natural, agricultural conditions-was already performed. [17,18] In previous studies, [19,21] it could be clearly shown that the main portions of cyrodinil's bound residues was located in the lignin, which is generally considered as not bioavailable.…”