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All Journal Chemistry Indonesian Journal of Chemical Research Journal of Applied Agricultural Science and Technology Journal of The Indonesian Society of Integrated Chemistry
Warmiati, Warmiati
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Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Education Engineering Environmental Science

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Reaction Stability Test of Hexavalent Chromium Complex with 1,5-Diphenylcarbazide in Analysis using UV Visible Spectrophotometer Warmiati, Warmiati; Wijayanti, Wijayanti
Indonesian Journal of Chemical Research Vol 11 No 3 (2024): Edition for January 2024
Publisher : Jurusan Kimia, Fakultas Sains dan Teknologi, Universitas Pattimura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/ijcr.2024.11-war

Abstract

A reaction stability test of hexavalent chromium complex with 1,5-diphenyl carbazide in analysis using a UV Visible Spectrophotometer has been done in this study. This study aims to find out the colored complex stability for the reaction of chromium hexavalent and diphenyl carbazide in the analysis of hexavalent chromium using a UV Vis spectrophotometer in terms of time. The sample was measured in 540 nm of wavelength with 10, 30, 60, 90, 120, and 180-minute time intervals. Each interval was carried out with two times replications. There were no significant differences in the colored complex until the 180-minute time interval, and the measurement of Cr(VI) concentration showed similar results. This analysis exhibits a level of precision and accuracy, evident from the RPD values below 10 % and the recovery values falling within the range of 90 – 110 %. It means that the reaction of hexavalent chromium complex with 1,5-diphenyl carbazide in analysis using a UV Visible Spectrophotometer is stable.
Verification Method for Determination of Melting Temperature and Enthalpy Changes (∆H) Using Differential Scanning Calorimeter Warmiati, Warmiati; Wijayanti, Wijayanti
Journal of The Indonesian Society of Integrated Chemistry Vol. 15 No. 2 (2023): Journal of The Indonesian Society of Integrated Chemistry
Publisher : Pendidikan Kimia FKIP Universitas Jambi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22437/jisic.v15i2.27198

Abstract

Verification of measurement method for determination of melting temperature and enthalpy changes using Differential Scanning Calorimeter has been carried out. This study was done to ensure that the method used can be applied in the laboratory with valid results and uncertainty. The verification method in this research consists of accuracy and precision. Accuracy was done by comparing measurement results with reference values using the t-student test. Precision can be seen in its repeatability and reproducibility. In this study, method verification of melting temperature measurement was carried out by thermal analysis using Differential Scanning Calorimeter (DSC) based on ISO 11357-3: 2018 method concerning determining temperature and enthalpy changes in melting and crystallization. The results showed that the method used to determine melting temperature and enthalpy changes (∆H) had met the repeatability and reproducibility requirements. The RSD (Relative Standard Deviation) value was less than 2%, and the accuracy met the acceptance requirements with a t-count smaller than the t-table in a 95% confidence level. It means that the results are not significantly different from reference values, so the method can be used in the laboratory. Keyword: verification method, melting temperature, differential scanning calorimetry
Transesterification of Palm Olein to Fatty Acid Methyl Esters (POle-ME) Using Base Catalysts Utami, Ratri Retno; Saputra, Andri; Satwikanitya, Pani; Sya’bani, Muh Wahyu; Warmiati, Warmiati; Indahwati, Luthfi Auliya; Ilmannafia, Danuraja
Journal of Applied Agricultural Science and Technology Vol. 9 No. 3 (2025): Journal of Applied Agricultural Science and Technology
Publisher : Green Engineering Society

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55043/jaast.v9i3.344

Abstract

Palm olein esters are potentially convertible into epoxy oil, which can serve as a plasticizer. Palm olein can be reacted with alcohol in the presence of a base catalyst in a process named transesterification. This study aimed to investigate the application of palm olein to produce fatty acid methyl esters (POLe-ME) using sodium hydroxide and potassium hydroxide as catalysts, which are then evaluated for their potential as plasticizers. The research process involved selecting raw materials based on the iodine and acid numbers. Subsequently, transesterification was conducted using 1% base catalysts. The characterization of POle-ME included evaluating its acid number, iodine number, viscosity, fatty acid composition, and functional groups. The findings indicate that using a molar ratio of oil to methanol of 1:6 and potassium hydroxide as a catalyst achieved the highest yield at 94.99%. The produced POle-ME exhibited a peak at 1436 cm-1, indicating the presence of a methyl ester functional group. The fatty acid composition of POle-ME consisted predominantly of oleic unsaturated fatty acid (C18:1) at 49.13%. Additionally, POle-ME exhibited an iodine number of 60.42, an acid number of 1.395, and a viscosity of 7.16 mPa·s, indicating its potential as a raw material for epoxy oil (plasticizer) production.
Co-Authors Hernandha, Rahmandhika Firdauzha Hary Ilmannafia, Danuraja Indahwati, Luthfi Auliya Iswahyuni Iswahyuni Muh. Wahyu Syabani Nurwijayanti Prayitno, Kutut Aji Ratri Retno Utami Saraswati, Henny Satwikanitya, Pani Wijayanti Wijayanti