UK – Minerva, a specialist analytical laboratory, has come up with a Liquid Chromatography with tandem mass spectrometry (LC-MS-MS) procedure for trace-level detection of the pesticides oxymatrine and matrine in Chinese honey.
Matrines and oxymatrines are herbal alkaloids, which can be found in plants from the family Sophora flavescens, a shrub-like tree growing extensively in some regions of China. They are also used as pharmaceutical agents and pesticides, among others, due to their insecticidal activity.
Within the past 12 months, there have been four EU Rapid Alert System for Food and Feed (RASFF) alerts concerning detectable levels of the pesticides oxymatrine and matrine in Chinese honey. Most of these alerts related specifically to Chinese Acacia honey.
Last year in August, France also recalled some retail Acacia honey containing ‘high’ levels of oxymatrine.
Sophora flavescens trees are reported to be found in regions where Acacia trees are also copious and therefore where Acacia honey is produced.
Since the two tree species flower over the same short period of time, honey bees foraging on Sophora nectar can introduce natural oxymatrine and matrine to the Acacia honey. Traces of these compounds may also be introduced into the honey through their commercial formulations in the region.
Notwithstanding the possibility that detected residues of matrine and oxymatrine may be due to natural occurrence, the UK classifies them as pesticides.
The EU and UK have not set the maximum residue level (MRL) for the pesticides in honey and as such do not permit their presence. The legal MRL for each of these compounds in all food commodities including honey is 0.01 mg/kg parts per million(ppm), or 10 parts per billion (ppb) by default.
Triggered by the rapid alerts, the EU set the 0.01 mg/kg limit for oxymatrine last year July.
Honey analysis is a core competence of Minerva with the company offering an extensive range of both macro and trace analyses including commercial, adulteration and contaminants testing.
For the matrix honey, in several thousand pesticide analyses since the beginning of 2019, the Tentamus Group has detected matrine and oxymatrine in only 40 samples. In 50% of the cases the levels found were above 0.01 mg/kg with positive samples originating from China.