Analysis of manganese and zinc in rice rain and rice husk with modification of sulfuric acid digestion method

Abstract

Heavy metal is abundant in nature and it has been widely used in many types of industrial activities. The overuse of pesticides without limit and improper waste disposal activities were among of the most significant cause of heavy metal pollution in the environmental. In this study, it focuses on modification of digestion method of heavy metal in rice grain and rice husk. The aim of heavy metal in this study is zinc and manganese. The digestion method used is sulfuric acid digestion. The parameters chosen for analysis are different concentration of sulfuric acid (1M, 2M, 3M, 4M and 5M), digestion temperature (250°C, 255°C, 260°C, 265°C and 300°C) and digestion time (10min, 15min, 20min, 25min and 30min). After the digestion process, the sample is further analyzed for identification of target analytes of zinc and manganese in the sample. The analysis of concentration of metal elements was detected using AAS. The modified sulfuric acid digestion method yields higher value of Mn which was 5.286 mg/l in rice grain and 6.845 mg/l in rice husk, while higher value of Zn in rice grain and rice husk which are 2.493 mg/l and 6.628 mg/l respectively compared to non-modified sulfuric acid digestion method which value of Mn was 4.902 mg/l in rice grain and 5.044 mg/l in rice husk, while higher value of Zn in rice grain and rice husk which are 1.656 mg/l and 4.565 mg/l. However, the concentration of manganese and zinc in the rice grains and rice husks were still below the maximum levels as stipulated by World Health Organisation and Food and Agriculture Organization.