Update: Change to the residue definition for phosphonic acid and new maximum residue levels
As already announced in our magazine article from November 2024, the residue definition for the active substance fosetyl-Al was changed on April 29, 2025.
New residue definition
The previous definition:
“Fosetyl-Al (sum of fosetyl, phosphonic acid and their salts, expressed as fosetyl)”
has been replaced by:
“Phosphonic acid and its salts, expressed as phosphonic acid”
Reason for the change
Phosphonic acid residues in plant products do not originate exclusively from the use of fosetyl-Al. Other sources such as phosphonates (e.g., disodium phosphonate, potassium phosphonate), which are for example used as fertilizers, plant fortifiers, or soil improvers, can also lead to residues.
Since fosetyl-Al is rapidly broken down into phosphonic acid in the plant and it is not possible to distinguish its source analytically, the residue definition was changed by Regulation (EU) 2025/581. At the same time, the maximum residue levels were amended to take other sources of phosphonic acid into account.
New maximum levels (extract)
| Product | Until April 29th 2025 (Fosetyl-Al) | From April 29th 2025 (Phosphonic acid) |
|---|---|---|
| Tea | 5 mg/kg | 20 mg/kg |
| Green Coffee | 5 mg/kg | 20 mg/kg |
| Cocoa | 2 mg/kg | 20 mg/kg |
Since April 29th 2025 there is no maximum residue limit for fosetyl itself anymore. The general limit of 0.01 mg/kg also no longer applies.
Assessment in organic products
Using the new definition there is no more discussion about the use of fosetyl-Al if only phosphonic acid is detected. The BNN orientation value of 0.01 mg/kg is still applicable to fosetyl, even though this will hardly be relevant in practice.
Until December 31st, 2026, the following BNN orientation values apply to phosphonic acid and its salts (expressed as phosphonic acid):
• Annual and biennial crops: max. 0.05 mg/kg
• Perennial crops: max. 0.1 mg/kg
An expanded measurement uncertainty of 50 % can be taken into account [2].
Analysis of polar substances at CR3-Analytik
Phosphonic acid and fosetyl are polar substances that cannot be detected using the standard multi-residue method (QuEChERS). CR3-Analytik has established a specialized LC-MS/MS method for this purpose, which enables sensitive and reliable detection with very low limits of quantification.
Polar substances include:
• Fosetyl / Phosphonic acid
• Chlorate / Perchlorate
• Chlormequat / Mepiquat
• Diquat / Paraquat
If you have any questions about analysis or evaluation in accordance to Regulation (EC) No. 396/2005 or BNN orientation values for organic products, please do not hesitate to contact us.
Source:
[1] Regulation (EC) No. 396/2005 on maximum residue levels of pesticides
[2] BNN-Factsheet Phosphonic acid, Version December 2024