Phosphonic acid
Phosphonic acid is an intermediate in the preparation of other phosphorus compounds.
Phosphonic acid is a substance that has systemic effects on fungal infections, in particular helping combat downy mildew.
Organic derivatives of phosphorous acid, compounds with the formula RPO3H2, are called phosphonic acids.
Salts of phosphonic acid (sodium or potassium phosphonate) or its ester fosetyl are highly effective systemic fungicides, which not only exhibit fungistatic activities, but also stimulate the natural defence systems of the plants against pathogens.
As a result, even minor contents of phosphonate in organic food samples are interpreted as an indication of a not permitted fungicide treatment
EC / List no.: 237-066-7
CAS no.: 13598-36-2
Mol. formula: H3O3P
Since phosphonic acid was found to be effective against fungal diseases, in particular those caused by oomycetes, the use of its potassium and sodium salts and its ester fosetyl became very popular in agriculture (for reviews see Guest & Grant, 1991; Dann & McLeod, 2021).
Phosphonic acid was used as a plant strengthening agrochemical, because it enhances the defence systems of the plant against pathogens.
In the EU fosetyl-Al, potassium and sodium phosphonate were approved as fungicides in 2007, 2013 and 2014, respectively.
With Commission Regulation (EC) 839/2008 maximum residue levels (MRLs) were defined for fosetyl, expressed as the sum of fosetyl, phosphonic acid and their salts, which are based on peer reviews of the pesticide risk assessment of the corresponding active substances by the European Food Safety Authority (EFSA, 2012, 2013 and 2018). With their approval as active plant protection products, phosphonate salts came also into the focus of EU regulation (EC) No 834/2007 on organic production and labelling of organic products and the use of these chemicals is no longer permitted since 2013 in organic agriculture.
Residues of phosphonic acid in organic products are interpreted as a possible indication that rules of organic agriculture have been violated.
Although the German Association of Organic Processors, Wholesalers and Retailers (BNN, 2023) and the European Organic Certifiers Council (EOCC, 2019) have defined orientation values for phosphonate, above which checks at farm level should be initiated, there is a tendency at EU level to follow a stricter line and to start such investigations already at findings above 0.01 mg/kg, which is the common limit of quantification (LOQ) achieved by laboratories for most food products.
Even more affected are products for infant nutrition, as for these a maximum residue level of 0.01 mg/kg applies under EU regulation (EU) No 2016/127.
The Biofosf project “Solving phosphite issue in organic fruit and horticultural crops” tested alternative hypotheses to understand the frequent findings of phosphonate in products from organic agriculture and to propose legislative actions (Trinchera et al., 2020).
Translated names
acid fosfonic (ro)
acide phosphonique; (fr)
acido fosfonico (it)
Fosfonihappo (fi)
fosfono rūgštis (lt)
fosfonska kislina (1) (sl)
fosfonskābe (lv)
fosfonzuur (nl)
Fosfoonhape (et)
fosforsyrlighet (sv)
fosforsyrling (no)
foszfonsav (hu)
kwas fosfonowy (pl)
kyselina fosforitá (sk)
Phosphonsäure (de)
trihydroxophosphor (da)
àcido fosfónico (es)
ácido fosfónico (pt)
φωσφονικό οξύ (el)
фосфониева киселина (bg)
IUPAC names
acido triossofosforico
Also known as Phosphorous acid
Dihydrogenphosphonat
dihydroxy(oxo)phosphanium
PHOSPHONIC ACID
Phosphonic Acid
Phosphonic acid
phosphonic acid
Phosphonic Acid
Phosphonic acid
phosphonic acid
phosphonic acid;
Phosphonic acid; Phosphorous acid
Phosphor(III)säure
Phosphorous acid
phosphorous acid
Phosphorous Acid
Phosphorous acid
Potassium phosphite
triossophosphoric acid(III)
Trade names
Fosforigzuur
Orthophosphorous Acid
PA
Phosphonic acid
phosphonic acid
Phosphorige Säure
Phosphorige Säure min. 98,5 %
Phosphorige Säure min. 99,0 %
Phosphorigsäure
Phosphorous acid
Phosphorous Acid (PA)
Phosphorous acid 50%
Phosphorous acid 70%
Phosphorous acid 70% grade
Phosphorous acid 70% solution
Phosphorous acid crystalline
Phosphorous acid flake
PHOSPHOROUS ACID MBP
