KOVALEN: Jurnal Riset Kimia https://bestjournal.untad.ac.id/index.php/kovalen <p><strong>KOVALEN: Jurnal Riset Kimia</strong> is a peer-reviewed journal of chemistry that published by the Chemistry Department, Tadulako University, Indonesia. This journal concern with publishing the original research articles, review articles, and the current issues related to chemistry. Publishing frequency 3 issues per year, in April, August, and December. KOVALEN has been established since 2015 with volume 1 no 1 (December 2015).</p> <p><strong>ISSN:&nbsp;<strong><strong>2477-5398 (electronic)</strong></strong></strong></p> <p>The Scope of this journal including:<br>1. Theoretical and environmental chemistry study<br>2. Material and biomaterial synthesis, including their application&nbsp;<br>3. Isolation, purification, and modification of the natural product<br>4. Development and validation of analytical methods<br>5. Isolation and application of enzyme</p> en-US jr.hardi0803@gmail.com (Jaya Hardi) pasjan82@gmail.com (Pasjan Satrimafitrah) Tue, 01 Sep 2020 15:37:23 +0000 OJS http://blogs.law.harvard.edu/tech/rss 60 Karakterisasi Nanokomposit Poly(Lactic Acid)-Spent Bleaching Earth Regenerasi Termodifikasi https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15207 <p>Development of renewable resource-based polymers attracts attention to solve environmental problems due to the build up of polymer (plastic). Poly(lactic acid) (PLA) is one of the most widely used polymers which have good biodegradability and processability. The addition of fillers to the PLA matrix aims to improve the characteristics of the PLA, such as mechanical properties of nanocomposites of PLA. Thus, PLA can be use as substitution of fossil fuel-based polymer. Spent Bleaching Earth (SBE) can be used as a filler after regeneration process. SBE was extracted and oxidized to take its oil content. Then, SBE was modified with urea solution to increase the interlayer distance. In this study, structure of nanocomposites was characterized using X-Ray Diffraction and mechanical properties of nanocomposites were characterized using Universal Testing Machines. X-Ray Diffraction characterization results show that PLA-SBE nanocomposite and PLA-modified regenerated SBE nanocomposites do not form new peaks, so SBE and modified regenerated SBE is intercalated and partially exfoliated in the PLA matrix. The degree of intercalation/exfoliation is indicated by the results of characterization of mechanical properties. The mechanical properties of PLA-SBE nanocomposite are lower than neat PLA, whereas the mechanical properties of PLA-modified regenerated SBE nanocomposites are higher than neat PLA. The best mechanical properties of nanocomposites were obtained for PLA-5% modified regenerated SBE, with elongation and tensile strength, 3.26%, and 42.22 MPa, respectively.</p> <p><strong>Ke</strong><strong>y</strong><strong>words:</strong><em> nanocomposites,</em> <em>poly(lactic acid), regeneration, spent bleaching earth</em></p> Tika Paramitha, Johnner P. Sitompul Copyright (c) 2020 KOVALEN: Jurnal Riset Kimia https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15207 Tue, 01 Sep 2020 15:21:52 +0000 Retensi Ekstrak Karoten pada Olahan Mie Wortel (Daucus carrota L.) https://bestjournal.untad.ac.id/index.php/kovalen/article/view/12794 <p>Carotene extract from carrots (<em>Daucus carrota</em> L.) can improve the quality of processed noodles. Determining of carotene retention in processed carrot noodles during the storage period that has been done aims to know the reaction kinetics and shelf life of the noodles. Carrot noodles were stored for 8 weeks at room temperature and analyzed its carotene content by using a UV-Vis spectrophotometer every 7 days. The result showed that the retention of carrot noodles during storage of 0, 1, 2, 3, 4, 5, 6, 7, and 8 weeks was 53.64%, 53.19%, 52.49%, 51.68%, 51.07%, 46.30%, 45.96, 45.88, and 44.93%, respectively. The retention kinetics of carrot noodles during storage followed a zero-order reaction and had a shelf life of up to 30 weeks, 4 days, 4 hours.</p> <p><strong>Keywords:</strong> <em>carrot noodles, retention, self life</em></p> Putri Wahyuni, Ni Ketut Sumarni, Prismawiryanti, Jaya Hardi Copyright (c) 2020 KOVALEN https://bestjournal.untad.ac.id/index.php/kovalen/article/view/12794 Tue, 01 Sep 2020 15:23:41 +0000 Kinerja Elektroda Platina Terlapis Enzim Butirilkholinesterase-Selulosa Asetat-Glutaraldehida untuk Deteksi Diazinon https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15237 <p>Diazinon (o, o-diethyl-o [2-isopropyl-6-methyl pyrimidynyl] phosphorotioate) is one of the organophosphate group pesticides widely used to protect cabbage plants (<em>Brassica olarecea</em>). Pesticide residues left in plants can bind to the cholinesterase enzyme and cause system disruption nerve. Analysis of diazinon residues in cabbage plants needs to be done to determine the level of toxicity caused. The electrochemical biosensor method as an electrochemical sensor uses a working electrode of platinum wire coated with the enzyme butybholchesteresterase (BChE) and cellulose acetate (SA) membrane and glutaraldehyde (GA) can be used for the analysis of pesticide residues. The test results of the SA electrode composition of the 10% GA 20% membrane obtained Nernst factor prices 28.1 µV / decade with a measurement range of 10<sup>-9</sup> - 10<sup>-6</sup> M, detection limit value of 1.29 x 10<sup>-7</sup> M response time of&nbsp; 30 - 300 seconds.</p> <p><strong>Keywords: </strong><em>biosensor, butylochholesterase, membrane, electrochemistry</em></p> Thamrin Azis, Nurhaeni, Caterina Bijang, A. Nurwahida Copyright (c) 2020 KOVALEN: Jurnal Riset Kimia https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15237 Tue, 01 Sep 2020 15:31:31 +0000 Perubahan Bilangan Peroksida pada Blending VCO-Ekstrak Likopen Buah Tomat Berdasarkan Perbandingan Rasio dan Lama Penyimpanan https://bestjournal.untad.ac.id/index.php/kovalen/article/view/13132 <p>Utilizing of lycopene extract in VCO has serve as antioxidant agent that protected VCO from oxidation process during storage. Belnding of VCO and tomato lycopene extract has been done that purpose to determine changes in peroxide number in the mixture of VCO-lycopene extract tomatoes based on comparison of ratios and length of storage. Peroxide contents from the mixture of tomato extract with VCO were determined using a spectrophotometric method at a wavelength of 500 nm. The results showed that the best results were obtained at a ratio of 40: 3 (v/w) with peroxide numbers 0.08 meq O<sub>2</sub>/ kg, 1.38 meq O<sub>2</sub>/ kg, 1.84 meq O<sub>2</sub>/ kg, 3.21 meq O<sub>2</sub>/ kg, 3.46 meq O<sub>2</sub>/ kg and 3.83 meq O<sub>2</sub>/ kg respectively. Peroxide numbers increased with increasing storage time, the highest increase occurred at week 3 at a ratio of 40: 1 (v/w) which was equal to 9.62 meq O<sub>2</sub>/ kg. The addition of lycopene was better at reducing the VCO oxidation process than without the addition of lycopene.</p> <p><strong>Keywords</strong>: <em>peroxide value, VCO, lycopene, duration of storage, ratio comparison</em></p> Muqasyifah, Nurhaeni, Syamsuddin, Khairuddin Copyright (c) 2020 KOVALEN https://bestjournal.untad.ac.id/index.php/kovalen/article/view/13132 Tue, 01 Sep 2020 15:32:37 +0000 Penurunan Kadar Asam dalam Kopi Robusta (Coffea canephora) dari Desa Rantebua Kabupaten Toraja Utara dengan Teknik Pemanasan https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15133 <p>Robusta coffee (<em>Coffea canephora</em>) is the most widely produced coffee in Indonesia. The relatively high acid content causes robusta coffee to be less attractive to both local and international consumers. Acid levels in coffee can be reduced by heating techniques using water as a solvent because it is cheap and easy to obtain and water is also a safe solvent and has no side effects for health. Coffee bean water content was analyzed by heating to constant weight by the oven method, acid content by titration technique, and followed by organoleptic testing. The results of the analysis of water content for dry treatment of 10.02%, wet treatment of 10.35% and on heating for 15, 30, 45, 60, 75, and 90 minutes respectively at 9.99%; 10.34%; 9.70%; 10.40%; 11.65% and 11.36%. The results of the analysis of acid levels for the treatment of dry processing amounted to 3.65%, wet processing amounted to 3.42%, and for heating for 15, 30, 45, 60, 75, and 90 minutes respectively 3.03%; 2.76%; 2.51%; 2.39%; 2,32% and 2,28%. Organoleptic test results showed that the decline in the quality of coffee occurs when heating above 45 minutes. Based on research data it was concluded that the heating method can reduce acid levels in coffee beans with a maximum heating time of 45 minutes to maintain the quality of taste in coffee.</p> <p><strong>Ke</strong><strong>y</strong><strong>words:</strong> <em>Coffea canephora</em><em>,</em><em> organoleptic</em><em>,</em><em> warming u</em><em>p,</em><em> titration.</em></p> Syahruddin Kasim, Syarifuddin Liong, Ruslan, Alprianto Lullung Copyright (c) 2020 KOVALEN: Jurnal Riset Kimia https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15133 Tue, 01 Sep 2020 15:27:43 +0000 Sintesis Nanopartikel Perak Menggunakan Ekstrak Daun Eceng Gondok (Eichornia crassipes) Sebagai Bioreduktor https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15137 <p>Nanoparticles was done by adding water hyacinth leave extract to AgNO<sub>3</sub> 2mM solution with a ratio of 1:40. Formed silver nanoparticles were analyzed using UV-Vis spectrophotometer, SEM, XRD, PSA, and FTIR to determine its characteristics. Results showed that absorbance value increased if reaction time is increased. Maximum absorption was obtained at wavelength 432-446 nm by using UV-Vis spectrophotometer. Result of PSA analysis shows that the average size of silver nanoparticles formed is 93.2 nm while XRD analysis shows that the average crystal size of silver nanoparticles is 50.11 nm, with round shape and amorphous. Result of FTIR analysis to determine functional group that contributes to nanoparticle synthesis shows the contribution of OH group.</p> <p><strong>Keywords:</strong> <em>reduction method, silver nanoparticles, Eichornia crassipes, bioreductor</em></p> Syahruddin Kasim, Paulina Taba, Ruslan, Romi Anto Copyright (c) 2020 KOVALEN: Jurnal Riset Kimia https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15137 Tue, 01 Sep 2020 15:28:32 +0000 Aktivitas Antioksidan Likopen Buah Tomat (Solanum lycopersicum L.) Terblending dalam Minyak Padat Ikan Lele (Clarias sp) https://bestjournal.untad.ac.id/index.php/kovalen/article/view/13651 <p>Research on the antioxidant lycopene of tomato fruit (<em>Solanum lycopersicum</em> L.) blended in frying fat from catfish (<em>Clarias sp</em>) oil has been done. The purpose of this research is to determine the antioxidant activity of tomato lycopene before and after being grounded into frying fat and determine the quality of frying fat after being grounded with tomato lycopene. The antioxidant activity of tomato lycopene is determined by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Analysis of frying fat quality includes determination of pH, determination of FFA (free fatty acid) levels, determination of total fat content, measurement of water content, peroxide number and organoleptic observation. Antioxidant activity of tomato lycopen was very high, namely with inhibition value of 89.79%; 90.34%; 91.49% and 92.10%. Frying fat analysis showed high antioxidant activity of lycopene tomatoes with 50.67% inhibition; 51.63%; 51.39% and 51.23%. The results of the analysis of the quality of frying fat are nearly same with SNI quality standards, except for peroxide numbers.</p> <p><strong>Keywords</strong>: <em>tomato, lycopene, antioxidants, frying fat, catfish, DPPH</em></p> Eka Surya Wahyuningsih, Syamsuddin, Prismawiryanti; Dwi Juli Pusptasari Copyright (c) 2020 KOVALEN https://bestjournal.untad.ac.id/index.php/kovalen/article/view/13651 Tue, 01 Sep 2020 15:29:39 +0000 Uji Potensi Metabolit Sekunder Ekstrak Kulit Buah Petai (Parkia speciosa Hassk) terhadap Kadar Kreatinin dan Ureum Tikus Secara Spektrofotometri UV-Vis https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15225 <p>This study aims to determine the effectiveness of bitter beans peels (<em>Parkia speciosa </em>Hassk) &nbsp;extract on creatinine and urea levels, and the effective dose of the exctract on creatinine and urea levels. This research was a laboratory experiment using 25 rats which were divided into five treatment groups, each group consisting of 5 rats. Group 1 (normal control), group 2 (negative control) were given suspension of Na-CMC, groups 3, 4, and 5 respectively given petai rind ethanolic extract doses of 300, 400 and 500 mg/kg. The results showed that petai fruit (<em>Parkia speciosa</em> hassk) peels extract had an effect on creatinine and urea levels of diabetes hypercholesterolemia male rats by an effective dose of 300 mg/kg which has an effect on creatinine levels by an average of 0.38 mg/dL and ureum levels by an average of 12.9 mg/dL.</p> <p><strong>Keywords</strong><em>: petai fruit peels extract, secondary metabolite, c</em><em>reatinine</em><em>,</em> <em>u</em><em>reum,</em> <em>S</em><em>treptozotocin</em></p> Joni Tandi, Heru Khairul Muttaqin, Kiki Rizki Handayani, Sri Mulyani, Recky Patala Copyright (c) 2020 KOVALEN: Jurnal Riset Kimia https://bestjournal.untad.ac.id/index.php/kovalen/article/view/15225 Tue, 01 Sep 2020 15:25:24 +0000 Studi Perbandingan Aktivitas Antioksidan Xantofil dan Karoten Kapang Oncm Merah pada Berbagai Waktu Inkubasi https://bestjournal.untad.ac.id/index.php/kovalen/article/view/11547 <p>Research on a comparative study of antioxidant activity of xanthophyll and carotenoids from red <em>oncom</em>, mold in various incubation times has been studied. This study aims to determine the antioxidant activity of xanthophyll and carotene at various incubation times of red oncom cultured in corn cob medium. This study used a Completely Randomized Design (CRD) &nbsp;&nbsp;at variations in incubation time: 2, 3, 4, 5, 6, and 7 days. The results showed that the best antioxidant activity of xanthophyll and carotene was on the second day with antioxidant activity of 82.27% and 65.80%, respectively.</p> <p><strong>Keywords</strong>: <em>antioxidant activity, xanthophyll, carotene, carotenoids, red oncom</em></p> Sriwulan Indriani Pea, Khairuddin, Prismawiryanti Copyright (c) 2020 KOVALEN https://bestjournal.untad.ac.id/index.php/kovalen/article/view/11547 Tue, 01 Sep 2020 15:26:23 +0000 Analisis Kadar Glukomanan Dari Biji Durian (Durio zeibethinus Murr) dengan Metode Spektrofotometri pada Berbagai Waktu dan Suhu Hidrolisis https://bestjournal.untad.ac.id/index.php/kovalen/article/view/11582 <p><em>Durian</em> seeds are one type of seed that contains glucomannan. The aim is to determine glucomannan levels in the durian seed. The study was designed using a completely randomized design (CRD). The extracted glucomannan was determined by the spectrophotometry method at various temperature and hydrolysis time. The crude extract of glucomannan was hydrolyzed using 3 M HCl for 70, 80, 90, 100, and 110 minutes at 70, 80, 90, 100, and 110°C. The highest glucomannan concentration of 39.60% was obtained at a hydrolysis temperature of 100°C for 100 minutes. The analysis of the FTIR spectrophotometer shown that the vibration of the C-O-C functional group (glycoside bond) was obtained at the wavelength number of 1020.34 cm<sup>-1</sup> which is a characteristic of glucomannan.</p> <p><strong>Keyword</strong><strong>s</strong>:<em> glucoma</em><em>n</em><em>nan, d</em><em>urian seed</em><em>, hydrolysis, spectrophotometry</em></p> Darmawati Darmawati, Syaiful Bahri, Husain Sosidi Copyright (c) 2020 KOVALEN https://bestjournal.untad.ac.id/index.php/kovalen/article/view/11582 Tue, 01 Sep 2020 15:30:26 +0000