Fiber optic biosensor using Chlorella vulgaris for determination of toxic compounds.

A new biosensor is constructed for the detection of some herbicides based on kinetic measurements of chlorophyll-a fluorescence in Chlorella vulgaris cells. The microalgae are immobilized on removable membranes placed in front of the tip of an optical fiber bundle inside a homemade microcell. C. vulgaris was easily cultivated in laboratory and very sensitive to herbicides that effect the photosynthesis process. The response of the algal biosensor is studied in terms of detection limits, reversibility, and long-term activity. The effects of temperature and pH are also reported. The biosensor can be used to measure the concentration of a toxic chemical in the form of a single drop or dissolved in a continuous flow. The detection of 0.1 microg small middle dotL(-1) of a single herbicide as is required by European Community legislation for drinking water is possible with this algal biosensor especially for atrazine, simazine, and diuron.