|Abstract Title:||Development and Preparation of Reference Materials for Determination of Total Mercury in Soil from ASGM Area|
|Presenter Name:||Willy Nugraha|
|Company/Institution:||Prefectural University of Kumamoto|
|Session:||Special Session - Metrological Traceability for mercury analysis and speciation|
|Co-Authors:||Willy Nugraha,Koji Arizono,Yasuhiro Ishibashi|
Abstract Information :
Artisanal small-scale gold mining (ASGM) activities that cause severe mercury (Hg) pollution to the surrounding area of the mining area have received a global attention. Hg-contaminated soil is one of the global concerns of Hg pollution due to ASGM activities. To obtain the reliable data, reference materials (RMs) for determination of Hg in soil, as a key tool to achieve metrological traceability, is highly required since the availability of RMs are severely limited at present. Considering these facts, we conduct a feasibility study for producing an in-house RMs for total Hg (THg) in soil to enrich the variety of available RMs. We present the development of an in-house RMs for THg in Hg-contaminated soil, the method validation, and associated measurement uncertainty. Hg-contaminated in soils, as a material ? candidate, were collected in Cisitu village, Banten Province, Indonesia which is one of the largest ASGM hotspots. Soil samples were freeze-dried, milled, sieved, homogenized, and distributed in amber bottles. Several statistical tests were applied for the homogeneity and stability study of the samples of materials. The results showed that materials - candidate for in-house RM with THg content meet the heterogeneity requirement and stability requirement at -30øC, 5øC, and 20øC both short-term and long-term stability study. The results can be considered homogenous (Fcalculated < Fcritical) both between bottle and within bottle and stable at all the temperature reference based on T-test. The agreement of the results with reference value (CRM CC580) proven the accuracy of the method with 98.8% of recovery and 1.69 %rsd of repeatability. For calculating associated measurement uncertainty, several potential sources of uncertainty were evaluated based on bottom-up approach at 95% of confident level with coverage factor of k=2. Therefore, the produced soil reference material can be used for the quality control measurement, proficiency tests and inter-laboratory comparisons.