Analysis of diuron herbicide in Senegalese surface and groundwater depending on the soil depth by photochemically induced fluorescence (PIF)

The photochemically induced fluorescence (PIF) method for the quantitative analysis of diuron herbicide in natural waters is described. The analytical parameters, namely solvent, pH and irradiation time, have been optimized. PIF method was developed for the determination of herbicide in methanol (MeOH) and ethanol (EtOH). The obtained calibration curves gave correlation coefficients close to unity, with low values of the limit of detection (LOD = 1.0–1.6 ng/mL) and limit of quantification (LOQ = 3.2–5.2 ng/mL). Analytical parameters (LOD, LOQ) obtained indicate a very good analytical sensitivity of the PIF method. Examples of application to the analysis of diuron herbicide in spiked surface and groundwater yielded satisfactory mean recoveries values (85.7–103.3%). The relative standard deviation values obtained in spiked draining and well waters samples are between 4.4 and 7.9%, which demonstrates good reproducibility of the PIF method. A significant decrease in the recovery rate of diuron in natural water samples as a function of soil depth was observed. Dissolved organic carbon (NPOC) leads to an increase in the recovery rate in spiked natural water.