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Rusmini
Department of Chemistry, Faculty of Mathematics and Natural Sciences Universitas Negeri Surabaya
Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Energy Materials Science & Nanotechnology

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Stabilitas Kimia Air Minum Dalam Kemasan Alkali Berdasarkan Langelier Saturation Index dan Endapan Kalsium Karbonat Dandi Umar Faqih; Rusmini
Unesa Journal of Chemistry Vol. 15 No. 1 (2026): Vol 15 No 1
Publisher : Department of Chemistry, Faculty of Mathematics and Natural Sciences, Surabaya State University, located at Jl Ketintang, Surabaya, East Java, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/ujc.v15n1.p14-19

Abstract

Alkaline bottled drinking water is characterized by high pH and relatively high alkalinity, which may influence its chemical stability during storage. One commonly observed phenomenon is the formation of white precipitates that can reduce the perceived quality of the product. This study aimed to evaluate the chemical stability of alkaline bottled drinking water based on physicochemical parameter analysis, characterization of the formed precipitates, and calculation of the Langelier Saturation Index (LSI) as an initial indicator of calcium carbonate precipitation tendency. The study was conducted on ten alkaline bottled water samples from a single producer by measuring pH, temperature, total dissolved solids (TDS), alkalinity, and Ca²⁺ and Mg²⁺ ion concentrations. The white precipitates formed during storage were qualitatively analyzed and confirmed through reaction tests with hydrochloric acid. The results showed that all samples had pH values of 8.35-8.50, alkalinity of 146-154 mg/L as CaCO₃, and a dominance of Ca²⁺ ions over Mg²⁺ ions. All samples exhibited positive LSI values, indicating supersaturation with respect to calcium carbonate. These findings indicate that LSI is a relevant initial indicator for evaluating the chemical stability of alkaline bottled drinking water during storage.
Analisis MPN E. Coli dan Total Coliform pada Air Bersih di SPPG Kabupaten Malang Nuralya Yuniarwati; Rusmini
Unesa Journal of Chemistry Vol. 15 No. 1 (2026): Vol 15 No 1
Publisher : Department of Chemistry, Faculty of Mathematics and Natural Sciences, Surabaya State University, located at Jl Ketintang, Surabaya, East Java, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/ujc.v15n1.p28-32

Abstract

Clean water is water that meets the requirements for daily activities. The quality of clean water can be determined chemically, physically, and biologically. The purpose of this study was to determine the number of Coliform and E. coli bacteria in clean water samples. The method used is the MPN (Most Probable Number) method. The sample in this study was total sampling, namely the entire population was made into a research sample of 5 samples. There were 2 Coliform examination results that met the standard, namely SPPG A (0 MPN/100 ml) and SPPG E (0 MPN/100 ml). 3 samples did not meet the standard, namely SPPG B (> 1600 MPN/100 ml), SPPG C (6.8 MPN / 100 ml), SPPG D (39 MPN/100 ml). In the E. coli examination, there were 2 results that met the standard, namely SPPG A (0 MPN / 100 ml) and SPPG E (0 MPN/100 ml). Three results that did not meet the standards were SPPG C (350 MPN/100 ml), SPPG D (6.8 MPN/100 ml), SPPG E (4.5 MPN/100 ml). Based on the results of the clean water examination conducted, with a total of 5 samples, it showed that 2 samples met biological requirements.
Co-Authors Dandi Umar Faqih Nuralya Yuniarwati