ESPECTROFOTOMETRIA UV-VIS APLICADA À AVALIAÇÃO QUANTITATIVA DA CONCENTRAÇÃO DE FERRO EM ÁGUA POTÁVEL PROVENIENTE DO CAMPUS SEDE DA UFSM

Abstract

Water is essential in all aspects of life, requiring potable conditions to meet human consumption needs. Additionally, it plays a crucial role in advancing various societal activities. This study aimed to assess the quality of drinking water at six points on the main campus of the Federal University of Santa Maria, Rio Grande do Sul. Water samples were collected on two days, Monday and Friday, and stored under refrigeration until analysis. UV-Vis molecular absorption spectrophotometry was used for the quantitative determination of iron. The application of the methodology involved the crucial step of complex formation between the iron present in the samples and 1,10-phenanthroline. This process resulted in a solution with a distinctive orange color. Subsequently, iron quantification was performed by measuring the absorbance of this solution. A calibration curve was constructed using a stock solution of 200 mg L-1 of iron diluted in water in the range of 0.2 to 2 mg L-1. The limit of detection (LOD) of the technique was determined as 0.004 mg L-1, while the limit of quantification (LOQ) was 0.007 mg L-1. After completing the analyses, a comparison was made between the results obtained and Ordinance No. 888 of 2021 from the Office of the Minister/Ministry of Health regarding the iron concentration. It was found that the samples from buildings 13, 18, University Restaurant 1, University Restaurant 2, and Student House 2 are within the limits established by the legislation. On the other hand, the sample from building 17 exceeded the established limits, with an iron concentration of 0.781 mg L-1 for the sample collected on Monday and 0.588 mg L-1 for the sample collected on Friday. These values represent excesses of 2.60 and 1.96 times, respectively, compared to the limits allowed by current legislation.