Comparative detection of fluorinated xenobiotics and their metabolites through 19F NMR or 14C label in plant cells

The metabolism of a new fluorinated fungicide [N-ethyl-N-methyl-4-(trifluoromethyl)-2-(3,4-dimethoxyphenyl)benzamide] by Acer pseudoplatanus cells was studied concurrently through the use of 19 F NMR and with 14 C-labeled compound. Approximately 10 fluorinated compounds were observed by 19 F NMR in the culture; 5 of them were identified. The detection limit was <1 μM. Methanol appeared to be a useful solvent as it was able to dissolve the lipophilic active ingredient as well as the more polar derivatives. However, the use of chloroform allowed a better separation of the NMR signals for the derivatives fairly soluble in this solvent. The metabolism of the studied compound mostly occurred through ring demethoxylation and N-dealkylation. The more lipophilic derivatives diffused into the culture medium; in contrast, the more hydrophilic ones remained inside the cells. This work shows that the sensitivity and high resolution power of liquid 19 F NMR spectroscopy confirm its potential usefulness to study the metabolism of xenobiotics.