Fera’s specialist scientists in veterinary medicine residues conduct this test to highlight the levels of malachite green and crystal violet, and their metabolites leuco-malachite green and leuco-crystal violet dyes, within your food samples. Fera can provide the evidence required by regulators to verify that the levels of both dyes within your food products are compliant.

Malachite green is a triphenylmethane dye which has been used illegally as an inexpensive topical fungicide and acaracide in the aquaculture industry. Other triarylmethane dyes such as crystal violet could also be used for this purpose.

Malachite green and crystal violet are easily absorbed during waterborne exposure, similarly both substances are reduced metabolically by fish to form leucocrystal violet and leucomalachite green, able to persist in fatty fish tissue for long periods of time. This has raised concern about the possible occurrence of residues of these dyes in human food, producing a need for analytical methods to monitor for these agents and their metabolites at trace residue levels.

In the EU, the concept of the minimum required performance limit (MRPL) has been established for several substances which have been expressly prohibited from use in food producing animals, including the most important illegal dye, malachite green. The MRPL for malachite green and leucomalachite green is 2 µg/kg, as per Commission Decision 2004/25/EC.

The analytical method used at Fera for this test is based on liquid chromatography–tandem mass spectrometry (LC–MS/MS). The methods have been validated in accordance with the principles set out in Commission Decision 2002/657/EC, and our analysis is accredited to ISO17025 by the United Kingdom Accreditation Service (UKAS). Results for the testing is returned within 10 working days of receipt of sample.

Confirmatory Analysis

Confirmatory analysis, where required, will be at the same value as the analysis performed.  Fera will contact you beforehand to establish if the additional analysis is required.  The delivery time for confirmatory results will be 10 working days from your instruction to proceed.