Analysis of nitrofurazone in milk and milk products according ISO 22186:2020
Complementing our analytical portfolio for veterinary drugs with nitrofurazone
April 2022. Since April 2022, the Eurofins laboratories for Food & Feed testing in Germany offer the analysis of nitrofurazone in milk and dairy products according to ISO 22186:2020, adding another rapid method to its veterinary drug residue method portfolio. With the new method, the banned antibiotic can be analysed directly in the matrices milk and dairy products. This complements the previous indirect analysis via the metabolite semicarbazide (SEM) and can confirm whether illegal antibiotic use actually occurred.
Background, toxicity and legal requirements
Nitrofurazone is an antibiotic that belongs to the group of nitrofurans. Due to its mutagenic and carcinogenic effects, it has been officially banned in the EU since 1993. In the organism, nitrofurazone can be metabolised rapidly or can be bound on proteins. Therefore, the metabolite SEM is usually analysed in meat and animal products. SEM is regarded as an indicator of illegal use of nitrofurazone (EFSA Opinion 2015[1]). However, if the cow is treated with antibiotics, the parent substance nitrofurazone also passes into the milk and can be analysed using highly sensitive methods.
Decision 2003/181/EC[2] set the minimum performance limit for the determination of nitrofurans at 1 µg/kg per metabolite. However, with the entry into force of Regulation (EU) 2019/1871[3], the reference value for measures (RWM) will decrease to 0.5 µg/kg from 28 November 2022.
Background on the increased demand for nitrofurazone analysis
However, unlike the metabolites of the other nitrofurans, SEM is not only a metabolite of nitrofurazone, but can also occur naturally in products (e.g. carrageenan). In addition, it has been detected more and more frequently in products in which there is evidence that no nitrofurazone had previously been applied. An increasing number of mainly protein-rich, dried products are known in which SEM can be formed during the production process (e.g. spray drying) or storage (e.g. milk and egg powder). Furthermore, entry into the product can occur through PVC seals in screw caps.
Since the detection of SEM no longer clearly indicates the illegal use of nitrofurazone, it is useful to analyse nitrofurazone directly in the matrices where this is possible. For milk and dairy products, this is recommended by the International Dairy Foundation[4].
Analysis of nitrofurazone
Our experts from Competence Centre for Veterinary Drug Residues have many years of experience with LC-MS/MS analysis of more than 250 veterinary drugs in all relevant food and feed matrices.
For the determination of nitrofurazone in milk and milk products, the standard method of the International Dairy Foundation ISO 22186:2020 [IDF 245:2020] "Milk and milk products - Determination of nitrofurazone" is used in a slightly modified form. In preparation for the lowering of the reference values from November 2022, a lower limit of determination of 0.5 µg/kg has already been established. An isotope-labelled internal standard is used for each sample and represents the status quo in terms of precision and accuracy of the analytical results obtained. A working day measurement of calibration standards and food reference materials for critical control of the analytics are additional quality standards that increase the safety of testing.
Contact us
Do you have questions about the analysis of nitrofurazone? Contact your personal account manager or our expert Roma Nemitz-Sturm directly.
Relevant regulations and sources:
[1] EFSA Journal 2015;13(6):4140: Scientific Opinion on nitrofurans and their metabolites in food
[2] Commission Decision of 13 March 2003 as regards the setting of minimum required performance limits (MRPLs) for certain residues in food of animal origin
[3] Commission Regulation (EU) 2019/1871 on reference points for action for non-allowed pharmacologically active substances present in food of animal origin
[4] International Dairy Fondation (IDF): IDF-Factsheet Juli 2015 – Why semicarbazide is not a suitable marker for nitrofurazone in dairy products
