Penentuan Kadar Fosfat (PO43-) dan Nitrogen Total (N-Total) pada Air Sungai dengan Metode Spektrofotometri UV-Visible

Abstract

Research has been conducted on determining phosphate and nitrogen total levels in river water by UV-Visible spectrophototometry method at the UPT Laboratory of the Environment Office of North Sumatra Province. In determining phosphate levels, starting with the addition of phenolphthalein indicators to each sample, then a mixed solution (H2SO4 5N, potassium antimonyl tartate, ammonium molybdate, and ascorbic acid) and homogenized, then the solution is measured using a UV-Visible spectrophotometer at a wavelength of 880 nm. In determining the total nitrogen content, starting with the addition of NaOH - Potassium Peroxodisulfate solution to each sample, then sterilized at a temperature of 120oC for 30 minutes, cooled, and added solution HCl : Aquadest by comparison (1 : 16), then the solution measured using a UV-Visible spectrophotometer at a wavelength of 220 nm. From the measurement results then carried out calculations on the sample with code 01/AS to 05/AS, so that the results for phosphate levels were obtained which was 7,178200 mg/L; 7,103100 mg/L; 0,048443 mg/L; 0,466530 mg/L; and 2,325660 mg/L and for total nitrogen levels of 28,783500 mg/L; 29,884800 mg/L; 0,911860 mg/L; 5,991950 mg/L; and 14,993040 mg/L. In accordance with the Government Regulation of the Republic of Indonesia No. 22 of 2021 concerning the Implementation of Environmental Protection and Management, the river water quality standard value for class 2 with phosphate parameters of 0,2 mg/L and a total nitrogen of 15 mg/L. Of the five sample codes that have been analyzed, there is only one sample code that meets the phosphate quality standards, namely river water with a sample code of 03/AS and there are three sample codes that meet the quality standards. total nitrogen is river water with sample codes 03/AS, 04/AS, and 05/AS.