A crosslinked matrix of thylakoids coupled to the fluorescence transducer in order to detect herbicides

A new method to detect photosynthetic herbicides has been developed. It is based on the fluorescence activity of spinach thylakoids immobilised in a matrix of crosslinked albumin-glutaraldehyde. Among all the tested parameters, it was the area over the fluorescence curve (FA) which showed the greatest modification in the presence of herbicides. So that was therefore selected for the experiments. The optimal area was measured at 25 °C in a 10 mM phosphate buffer, pH 5.5. After immobilisation, the value of fluorescence area retained 77% of the activity after a 240-day storage at −18 °C. A good operational stability was given by the measuring of the fluorescence area every 10 min during 180 min at +5 and +25 °C. The limits of detection were determined for various photosynthesis inhibiting herbicides (corresponding to a 10% inhibition of FA). The greatest sensitivity for the detection of the phenylurea diuron (0.35 μg/L) was recorded and the order of sensitivity among the triazines and triazinones chemical classes were, respectively, metribuzin (2 μg/L), atrazine (3.5 μg/L), and cyanazine (10 μg/L). It was also possible to detect low concentrations of diuron in environmental water samples except for highly concentrated salt waters which modified the fluorescence activity of the thylakoid matrix. The results suggest that this system could be useful for monitoring of pollutants and environmental pre-screening.