Reflectometric interference spectroscopy for the determination of atrazine in natural water samples

We assessed the performance of a new sensing device based on reflectometric interference spectroscopy (RIFS) for the determination of atrazine in water samples. The correlation coefficients between concentrations of natural water samples measured by RIFS and by HPLC/GC were highly significant (0.903; p < 0.001) for the 31 surface water and groundwater samples tested, but very poor (0.190; p < 0.5) for the 9 lysimetric plate water samples. Marked interferences were observed with humic acid solutions, probably due to strong nonselective polyanion-polycation binding to the transducer surface, which involves a basic aminodextran. The detection limit was 0.35 mu g/L. Since there was a significant cross-reactivity of simazine and terbutylazine, the present system might be used for screening groups of pesticides rather than for the determination of a single molecule. The total duration of one determination, 15 min, enables semicontinuous measurements without any sample pretreatment. No significant alteration of the sensor was observed after 160 determinations. These results demonstrate the potential of RIFS as a new technology for monitoring pesticides in natural water samples.