Jurnal Riset Kimia
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Rapid Detection and Quantification of Gambir Adulteration Using ATR-FTIR Spectroscopy Coupled with Chemometric Analysis
Get PDFGambir (an extract from Uncaria gambir Roxb.) is a valuable Indonesian herbal product susceptible to adulteration for economic gain. In this study, we developed a rapid, non-destructive method to detect and quantify adulteration in gambir using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy combined with chemometric analysis. In total, 32 gambir samples were prepared, including authentic gambir, samples adulterated with a fertilizer (SP36) at 0–50% w/w, quality control (pooled) samples, and a market sample of unknown purity. FTIR spectra (4000–600 cm−1) were collected. The spectral data were preprocessed and analyzed with PCA, SIMCA, and PLS-R. PCA revealed clear clustering of samples according to adulterant concentration, with the first two principal components capturing more than 99% of total variance. Chemometric classification models successfully distinguished authentic gambir from adulterated samples: SIMCA showed clear separation, with the 1% adulterant concentration sample clustering near authentic gambir, while the PLS-R calibration model achieved excellent linearity (R² ≈ 0.988) in predicting adulterant levels, with low RMSECV (≈ 0.0375) and a detection limit of ~0.54% adulterant concentration. When applied to a gambir sample obtained from the market, the PLS-R model indicated ~25% adulterant concentration. These results demonstrate that FTIR spectroscopy combined with multivariate analysis can effectively detect and quantify even low levels of adulterant concentration in gambir. This approach offers a fast and reliable tool for quality control and authentication of herbal products prone to adulteration
Isolation and Elucidation Structure of the Chemical Component from Ethyl Acetate Subfraction of Kelakai Stems (Stenochlaena palustris)
Get PDFKelakai (Stenochlaena palustris) belongs to the Blechnaceae family and offers numerous health benefits due to its chemical components. The isolation and structure elucidation of the chemical components from the ethyl acetate subfraction of the kelakai stems (Stenochlaena palustris) have been carried out. The isolation process began with the preadsorption of 241 mg of the E5.6 subfraction, which was then subjected to separation and purification using column chromatography. Three solvent combinations were used in the process: (chloroform 100%, chloroform: methanol (9:1), and chloroform: methanol (8:2)). The choice of solvent was based on the stain patterns observed in thin-layer chromatography (TLC). The chemical component was successfully isolated after chromatography, resulting in a white needle crystal weighing 15.2 mg and a single spot on the TLC, which was monitored using ultraviolet light at a wavelength of 254 nm. The structure of the chemical component was elucidated using 1H-NMR and 13C-NMR spectra, and comparison with literature data confirmed that the isolated compound from the ethyl acetate subfraction of the kelakai stems is succinic acid
Classification using FTIR and UV-Vis spectra combined with chemometrics and GC-MS profiles of Brucea javanica fruit extracts with different extracting solvents
Get PDFBrucea javanica L. Merr. has long been used for its antimalarial, anti-diabetic, antibacterial, and antioxidant effects. Its bioactivity depends on both its chemical constituents and the type of solvent employed during extraction. Integrating FTIR and UV-Vis spectral data with chemometric approaches enables classification of fruit extracts based on the solvent used, while GC-MS analysis provides detailed compound identification. Using sonication, extraction with methanol, ethyl acetate, and n-hexane produced yields of 30.61% ± 0.80, 19.20% ± 0.75, and 18.12% ± 0.89, respectively. FTIR spectra were recorded over 600–4000 cm⁻¹, and UV-Vis spectra were measured across 200–800 nm. Analysis showed that ethyl acetate and n-hexane extracts exhibited similar profiles, which differed from that of the methanol extract. PCA successfully distinguished all three extracts, with cumulative PC1 and PC2 values above 70%. FTIR-based PCA provided better separation due to its broader fingerprint region compared to UV-Vis spectra. GC-MS results revealed that the compound profiles were largely similar across the extracts, although more compounds were detected in the methanol extract than in the ethyl acetate or n-hexane extracts
Optimization of P3HT:PCBM Bulk Heterojunction Polymer Solar Cells: Effects of Annealing Temperature and Active Layer Composition
Get PDFP3HT:PCBM-based polymer solar cells have demonstrated potential as an affordable substitute for conventional silicon-based photovoltaics. The performance of P3HT:PCBM bulk heterojunction solar cells is examined in this work in relation to the annealing temperature and the composition of the active layer. The morphology of the active layer was characterized using SEM, while the electrical properties were measured using current-voltage (I-V) characterization. Our findings show that 150°C is the ideal annealing temperature, resulting in the maximum power conversion efficiency (PCE) of 2.58%. SEM analysis revealed that this temperature produces the most homogeneous surface morphology. Additionally, a P3HT:PCBM ratio of 3:1 resulted in the best device performance, with a PCE of 4.36%. Short-circuit current and open-circuit voltage increase when the blend's P3HT level increases. These results offer important information for optimizing the production of P3HT:PCBM-based polymer solar cells, which could lead to increased organic photovoltaic device efficiency and possible commercial outcomes
Sintesis dan Karakterisasi Solid Polymer Electrolyte (SPE) Berbasis Nanofiber Selulosa untuk Menunjang Baterai Litium Berdensitas Tinggi dan Ramah Lingkungan
Get PDFLithium battery as one of the energy storage has two important elements, namely electrodes and electrolyte. Electrolyte is a part of the battery element that has undergone many developments. In this study, the manufacture of electrolytes in the form of Solid Polymer Electrolyte (SPE) was carried out by utilizing the abundant availability of nata de coco. The nanofibrous cellulose structure in Bacterial Cellulose (BC) nata de coco has the advantages of good porosity, flexibility in surface functionality, compact porous structure that provides abundant ion pathways and hetero atoms (oxygen atoms) with free electron pairs that facilitate ionic conduction. The SPE synthesis process was carried out by varying the soaking time of nata de coco in ethanol, namely 1, 2 and 3 days to determine the structure with optimal results. FTIR characterization results show the synthesis of cellulose nanofiber has the same groups as commercial cellulose groups in the form of O-H, C-H, C=O and C-O. CV characterization results show the SPE electrolyte has good redox properties, especially in the 2-day variation with the highest specific capacitance. The EIS test showed the lowest resistance in the 1-day variation sample with a conductivity of 0.017 ohm-1
The Impact of pH Preparation on the Physical Nature and Metal Phase of Zeolite-Supported Metal Catalyst
Get PDFThe synthesis of CoMo/USY catalysts has been widely carried out. However, the bond strength between metal and USY is still a problem. Therefore, this research has synthesised the catalyst with the chelating agent ethylenediaminetetraacetate (EDTA). Apart from that, the effect of pH on the characteristics of the catalyst is also reviewed. This research aims to analyse the effect of preparation pH on catalyst characteristics. In the preparation process, the pH of the solution is set at values of 2, 7, and 8. Catalyst activation includes a calcination process and reduction. The catalyst characterisation uses XRD, GSA, and FTIR instruments to determine phase composition, specific surface area, and functional groups. The result showed that pH preparation significantly influenced the metal loading on the catalyst and reached a maximum at pH 8. The surface area is not directly related to the pH of the preparation but has the opposite property depending on the amount of metal added. Meanwhile, it was found that the CoO and MoO3 phases were achieved on the catalyst by all pH preparations. On the other hand, the CoMo alloys are present on the catalyst at pH 7 and 8, while the Co and Mo elements are visible at pH 2. The difference in pH during the synthesis process impacts the shift in the absorption wave number of the OH vibration
Isolasi Senyawa Metabolit Sekunder Dari Ekstrak Heksana Batang Kelakai (Stenochlaena palustris):
Get PDFIsolation is a method of obtaining pure secondary metabolite compounds from plant extracts, which provide benefits such as health, medicine, cosmetics, and agriculture. This research has been carried out and aims to isolate the secondary metabolite compound from the hexane extract of the kelakai stems (Stenochlaena palustris). Phytochemical screening of that extract resulted in a positive-containing steroid. The isolation method includes the separation of hexane extract with column chromatography using silica gel as the stationary phase and eluted successively with hexane, chloroform, and ethyl acetate (step gradient polarity). The column chromatography of the hexane extract resulted in five fractions (H1–H5). Furthermore, fraction H3 was purified to obtain a white needle crystal. The isolated compound spot is invisible in thin-layer chromatography (KLT) under an ultraviolet lamp at 254 nm and 365 nm wavelengths. The isolated compound structure was elucidated by proton and carbon nuclear magnetic resonance (NMR), and mass spectroscopy (MS), as well as comparisons with literature data. The isolated compound is a group of steroids identified as β-sitosterol with the molecular formula C29H50O
Profile of a Composite Based on Bacterial Cellulose and Polyvinyl Alcohol as a Drug Release Matrix for Tetracycline Hydrochloride
Get PDFBacterial cellulose (BC) is a natural polymer with good mechanical properties and hydrophilicity. Polyvinyl alcohol (PVA) is a synthetic polymer widely used in medicine. Both have been researched for their potential in drug release and acceptance. This study aims to determine the role of BC and PVA as drug release matrices for tetracycline hydrochloride (TCH), with additional fillers such as graphite (G) and TiO2. The results showed that the composites with BC matrix had lower mechanical properties than those with PVA matrix, with tensile strength values of 6.4075 and 17.446 MPa, respectively. However, the BC matrix was superior in porosity and swelling ability. The drug release testing of TCH from the composites showed that the appropriate model to describe drug release in BC matrix composites was in zero order, while the PVA matrix was in first order. The antibacterial activity of the composites on both matrices was tested against Staphylococcus aureus. The results indicate that both composites have potential applications in promising biomedical fields
The Density Functional Tight Binding (DFTB) Approach for Investigating Vacancy and Doping in Graphene as Hydrogen Storage
Get PDFA study on graphene defects for hydrogen storage has been successfully conducted using the Density Functional Tight Binding (DFTB) approach. The research aimed to modify solid materials for hydrogen storage. A 4 × 4 × 1 unit cell was used as the basis, while the supercell used for sampling was enlarged to 40 × 40 × 1. The analyzed data included changes in Density of States (DOS), Fermi level shifts, electronic band structures, formation energy, adsorption energy, and isosurfaces for each graphene orientation. It has been observed that modifying the surface structure of graphene can alter the electronic properties of graphene. This is indicated by shifts in DOS intensity, characterized by increased electronic intensity around the Fermi level total density charge different. The interaction energy between graphene and hydrogen gas has been determined to be -0.0155 eV for H-epoxy graphene, -0.4941 eV for H-monovacancy graphene, and -0.0424 eV for HN-monovacancy graphene. The presence of the vacancy increase the potential to adsorp hydrogen
