Development of Soil Sample Preparation by Means Acid Digestion without Heating with Teflon Method for Nickel Analysis

Abstract

The development of acids digestion method without heating has been done. This research was conducted by comparing the result of wet acids digestion method without heating by using Teflon method compared with international standard methods, namely US-EPA 3050b and ISO 14869-1 methods. Variations of acid or acid mixtures are performed which are sulfuric acid, a mixture of nitric acid with hydrochloric acid (aqua regia), and a mixture of nitric acid with sulfuric acid (sulfonitrate acid). The results of the digestion were analyzed using atomic absorption spectrophotometer (AAS). Method of validation was conducted by determination of linearity, precision value, limit of detection and limit of quantification. Validation of Teflon method has been done by comparing the results of Teflon method with US-EPA 3050b and ISO 14869-1 with t-test and ANOVA for each variation of the same acid or mixtures of acids. Based on the precision test, all the acid digestion treatment for the soil samples (both single and mixed acids) produced low precision of Teflon method compared to US-EPA and ISO methods. In addition, t-test and ANOVA (F-test) showed that there is significant difference in the results of digestion data analysis of the Teflon method with international standard method. The shaking time variation for the Teflon method produced significant result in nickel concentration.