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Journal : Science and Technology Indonesia

Validation of Mercury Speciation Analysis in River Around Artisanal Small-Scale Gold Mining Area in West Nusa Tenggara, Indonesia Dhony Hermanto; Nurul Ismillayli; Nindi Herdiyanti; Siti Raudhatul Kamali; Soraya Aulia
Science and Technology Indonesia Vol. 7 No. 3 (2022): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (718.095 KB) | DOI: 10.26554/sti.2022.7.3.379-384

Abstract

A method for determining mercury concentration using a mercury analyzer in a river water sample was validated according to ISO/IEC 17025. Analytical performance including linear range, limit of detection, precision and accuracy were evaluated. Mercury speciation profile was obtained from Pelangan River at three areas within Dusun Rambut Petung, an area with the highest amount of artisanal small-scale gold mining (ASGM) in Lombok, West Nusa Tenggara. Then, their concentration in each species was measured using sequential extraction. Good curve linearity was obtained in the concentration range of 0.1-5.0 µg/L and the limit of detection was 0.014 µg/L. The developed method has good precision and accuracy with a RSD value <10% and a recovery of 94.16-101.91%. The detected fraction of mercury in the Pelangan river is organomercury, elemental mercury, and sulfide-bound species with each concentration of 0.732±0.032; 0.350±0.027; and 0.850±0.027 µg/L, respectively. The measurement results showed conformity with the reference method using CV-AAS. Therefore, this method can be applied to determine mercury levels in water for monitoring environmental quality.
Transmission-Based Energies of Prime Coprime Graph for Integers Modulo Group Romdhini, Mamika Ujianita; Abdurahim; Maharani, Andika Ellena Saufika Hakim; Kamali, Siti Raudhatul
Science and Technology Indonesia Vol. 10 No. 3 (2025): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.3.759-765

Abstract

Graphs are an excellent instrument that provides an algebraic structure for visualizing and interpreting molecule structures and characteristics. As a result, the problem statement arises regarding how we can interpret graphs with eigenvalues concerning their corresponding matrices. Such questions can be answered by studying spectral graph theory. This research focuses on graphs whose vertex sets are group elements in which the structure of ℤn groups and the definition of a prime coprime graph serve as the foundation for the graph building used in this study. The matrix construction of the graph is based on transmission-based matrices including Weiner-Hosoya and distance signless Laplacian matrices. Research methods include investigating the transmission properties and formulation of the characteristic equation using block matrices. The results obtained are a comprehensive analysis of eigenvalues, spectrum, and spectral radius leading to the prime coprime graph energy for ℤn groups corresponding to both matrices.