Study of Analytical Method for Measure Phosphorus in Groundwater by UV Spectroscopy Visible

In the present work, a spectrophotometric method was used for the determination of phosphorus in water samples from artesian wells of cities in the southwest of Bahia-Brazil. The method was based on the reaction of ammonium molybdate in acid medium with orthophosphate ions to form a complex, after reduction with ascorbic acid and quantification by spectrophotometry. The maximum wavelength of the complex formed was at 880 nm. The calibration curve showed a linear relationship between phosphorus concentrations and absorbance in the concentration range of 0.04 to 1.0 mg L-1 with a linear correlation coefficient equal to 0.993. The method quantification limit was evaluated at 0.04 mg L-1 . The addition and phosphorus recovery tests showed that there was no matrix interference in the procedure. The RSD value was less than 0.07% and recovery was within the range of 97.2 to 98.8%, indicating good precision and accuracy of the method. The phosphorus concentration in the samples analyzed was between 0.134 ± 0.002 to 1.106 ± 0.053 mg L-1 , exceeding the maximum limit established by CONAMA for freshwater, belonging to Class I.