DIANA PUIU, TOMA GALAON, LILIANA CRUCERU, MARCELA NICULESCU, MADALINA MIHALACHE, LUOANA FLORENTINA PASCU, MARIANA POPESCU NEW STUDY CONCERNING THE BIODEGRADATION OF DIMETHOATE, CHLORPYRIFOS AND CHLORFENVINPHOS IN SOME MEDICINAL PLANTS Herbal drugs are widely used in pharmaceutical industry due to their beneficial effects on human health. The current research was carried out to evaluate the organic pollutant degradation in the flower part of the plant after a foliar application of pesticides. Also, based on the fact that selected pesticides are highly toxic to bees, it is important to monitor the removal rate of the pollutant. Under laboratory conditions, the marigold and French flowers (Calendula Officinalis and Tagetes Patula) were spiked with a mix of organophosphorus insecticide, dimethoate, chlorpyrifos and chlorfenvinphos, where the first two substances are still used on Romanian territory. The samples were extracted at different time moments over 300 min after sprayed treatment in order to evaluate the concentration in flower. The analytes were quantified by using gas chromatography with flame photometric detection (GC-FPD) technique. The developed method ensures the quality and comparability of analytical results, with a good sensitivity in determining the analytes over the concentration range 5-250 µg/L.