Determination of Cr (VI) and SO42- Using UV-Vis Spectrophotometry in River Water Samples at the Environment Office of Semarang City

Abstract

Analysis of hexavalent chromium (Cr-VI) and sulfate ions (SO42-) in river water in the city of Semarang aims to find out the quality of river water compared to Government Regulation No. 22 of 2021. Concentration of chromium (Cr-VI) were determined using the spectrophotometry method with 1,5-diphenylcarbazide reagent and analyzed with a UV-Vis spectrophotometer at a wavelength of 540 nm, while the determination of sulfate levels (SO42-) using the turbidimetric method uses the same spectrophotometer at a wavelength of 420 nm. The results of the analysis obtained Cr(VI) of 0.0094 mg/L and 0.0096 mg/L while SO42- amounted to 17.2105 mg/L and 20.6842 mg/L. The results showed that river water based on PP Number 22 of 2021 on class II river water quality standards, river water quality is still good and can be used according to its designation because it is still below the maximum threshold of Cr(VI) and SO42- which is 0.05 mg/L for Cr (VI) and 300 mg/L levels for SO42-levels.