The metabolism of fosetyl-aluminium and the evolution of residue levels in oranges and tangerines

The metabolism of fosetyl‐aluminium to phosphonic acid in the peel of citrus fruit has been studied by gas chromatography using a nitrogen‐phosphorus detector and also with a flame photometric detector. At the same time the phosphonic acid residues remaining in the peel and the pulp of citrus fruit, as a result of the application of aqueous solutions of fosetyl‐aluminium at 2.5 g litre−1 to trees prior to harvest was determined.