Papers by Keyword: Gas Chromatography

Abstract: Caffeine, an alkaloid compound found in coffee, is widely known for its ability to stimulate the human central nervous system. The caffeine content in Sidomulyo robusta coffee was analyzed using a gas chromatography-flame ionization detector (GC-FID) with ultrasound-assisted extraction as a preparation method using methanol solvent for 21 minutes at 32°C. A TR-1MS column (15m x 0.25 mm ID x 0.25 μm film, non-polar column 100% dimethyl poly-siloxane) was used for the GC analysis. The injector temperature was set at 260°C and the detector at 280°C. The initial oven temperature was set at 100°C, held for 1 minute, then gradually increased by 5°C/minute up to 280°C and held for 2 minutes, with the optimal flow rate condition selected at 1.2 mL/min. This method met all verification criteria and exhibited linearity in the 100–600 mg/L range with a high correlation coefficient of 0.9929, demonstrating its reliability and accuracy in determining caffeine content in coffee samples

Abstract: Oils, e.g. linseed oil, has been used as mortar admixtures or components of lime-oil mastic since ancient times. The reason was either to increase the mortar durability and/or to prolong the mortar/mastic workability. Historic mortars are conventionally analyzed by means of X-ray diffraction and thermal analysis, but these methods are not able to detect the organic compounds directly. The goal of the present research was to evaluate the applicability of thermal analysis, infra-red spectroscopy, solid state NMR spectroscopy and gas chromatography for detection and possible quantification of linseed oil in prepared mortar containing, beyond the oil, just lime and calcite. Both applied spectroscopies were able not only detect the presence of oil but may be used also for study of the oil chemical transformation in the alkaline environment of the lime mortar. Thermal analysis is not able to identify kind of organic admixture, but when it is known that it is e.g. linseed oil, its quantification by help of Evolved Gas Analysis is very good. The results of gas chromatography of mortar’s extract are affected by the polymerization of oil in mortar. The total organic content analysis is providing good information about the total amount of organics in mortar. There in not any single method, which could provide all information about the oil admixture in mortar (kind of oil, content of oil, fate of oil after mortar’s mixing) by itself; the combination of techniques must be used.

Abstract: The theoretical aspects of wood material fire protection formation by esterification reactions are considered in the article. The reactivity of polysaccharides and polymers from which wood material is composed has been confirmed by the FTIR method. The IR spectra of the original standard samples of lignin and microcrystalline cellulose were taken and after treatment with solutions with concentrations of 10% of the mass. orthophosphoric (Н₃РО₄) and oxyethylene diphosphonic (CH₃C(OH)(H₂PO₃)₂) acids. Electron scanning microscopy revealed the crystallization of inorganic salts on the wood material surface, which play the role of flame retardants, as well as a film of organopolymer (polyhexamethylene guanidine polyphosphate), which forms a foamed layer of coke when heated. Thermogravimetric analysis (TGA) and gas chromatography (GC) methods show the mechanism of action of fire protection provided to wood material. The formation of foamed coke is visually shown and the results on the effectiveness of fire protection on the example of wood material treatment with a mixture of diammonium phosphate and ammonium sulfate are obtained.

Abstract: Agarwood has been used for its fragrance and medicinal properties in Asian culture for centuries. In recent years, agarwood gains its popularity in the west due to its usage in perfume formulation. Unfortunately its supply not meets the augmentation market demand. This is mostly because of depleting nature agarwood reservoir and lack of induction technique that can produce agarwood consistently in the plantation. In this study, we look into a case where artificial inducing technique successfully produced high quality agarwood. To assure its quality, agarwood chip was analysed by Gas Chromatography for its chemical profiles. Discovered compounds were identified as sesquiterpene group which also had been characterized as major agarwood compound listed on previous studies. Few compounds that are detected such as δ-cadinene (0.20%), jinkoh-eremol (22.09%), epi-α-cadinol (4.74%), agarospirol (3.75%) and others. Soil condition that contributes into this agarwood formation; soil analysis on physical properties, chemical properties and nutrients content of the soil have been analyzed. Based on the findings, soil condition is an important factor to successfully induced high quality agarwood.

Abstract: We have developed a new testing device which is capable of detecting hydrogen gas release during slow strain rate tensile testing (SSRT) under ordinary pressure. The device is composed of an SSRT machine equipped with a closed chamber with an inspection window that is connected to gas chromatography with a semiconductor hydrogen sensor. Local strain distribution in the specimen during the SSRT is monitored dynamically with a digital image correlation (DIC) method. Hydrogen was pre-charged to aluminum alloys by means of friction in water process. Using the device, it was shown that hydrogen was released particularly in the stage of plastic deformation and fracture. In addition, the hydrogen gas release at the moment of fracture was clearly increased when the alloys were hydrogen-charged and tested at a slow strain rate. When we calculated hydrogen gas release from the fracture surface in Al-Zn-Mg base alloys tested at 3.3×10^-6 s^-1, the hydrogen amount was estimated to be 6.24×10^-10 mol /mm² in a hydrogen-uncharged alloy, and 1.30×10^-9 mol / mm² in a hydrogen-charged alloy.

Abstract: The method of gas chromatography was used to study of the stabilizing effect of the organophosphorus compound tetrakis (2,4-di-tert-butylphenyl)-4,4-biphenyl diphosphonite on polyether ether ketone. The possibility of maintaining the structure of polyetheretherketone under conditions of its extrusion processing without the risk of deterioration of the main technological and operational characteristics is revealed.

Abstract: Clove oil, extracted from dried floral buds of clove (Syzygium aromaticum), are used in topical products because it has antioxidant and antimicrobial activities. Microemulsions (ME) are stable emulsion which can be formulated by simple mixing of oil, water, surfactant and co-surfactant. The objectives of this research were to develop and evaluate clove oil-loaded ME for topical application by using Tween 80 as surfactant. Ethanol, isopropanol and propylene glycol (PG) were used as co-surfactants. Pseudo ternary-phase diagram showed that using ethanol and isopropanol provided larger ME area than using PG in all surfactant:co-surfactant ratio (SR; 1:0.5, 1:1 and 1:2). Up to 20% w/w of clove oil can be loaded in ME by using surfactant mixture of 60-80% w/w. The effects of various amounts of clove oil (5-20%) and surfactant mixture (60, 70, 80%) at SR of 1:1 on physico-chemical properties of ME were observed. All formulations are transparent with the pH values of 6.8-8.0. The droplets size of ME using ethanol and isopropanol as co-surfactant ranged from 10-100 nm while that using PG was higher. Conductivity values showed that all formulations were o/w ME. Zeta potential values revealed stable particles. For ethanol and isopropanol, ME containing 5-10% clove oil and 60-70% SM showed good physico-chemical stability. The amount of eugenol in clove oil analyzed by gas chromatographic (GC-FID) method was 82.27% v/v. The stability test of selected formulations (70% surfactant mixture at SR = 1:1) was evaluated from %eugenol remaining at room temperature and in refrigerator after 4-week storage. It was found that the amount of eugenol in the formulation was effected by the storage condition. Our results indicate that clove oil can be prepared in ME with physico-chemical stability by using Tween 80 and ethanol as surfactant system.

Abstract: Thermal oxidative stability of polyetherimide-based composite materials at processing temperatures was investigated using gas chromatography. The dependence of physico-mechanical and rheological properties on the composition of composites is established.

Abstract: Thermal and thermo-oxidative degradation, as well as crosslinking and "curing" processes of polyphenylene sulfide, depending on the heat treatment regimes, have been studied using gas chromatography. The effect of sorbed water in the polymer on the processes of thermal and thermo-oxidative decomposition of polyphenylene sulfide is shown and the optimal modes of drying the samples are established.

Abstract: The temperature-time regimes of drying of polyetheretherketone were revealed, during which it is completely possible to get rid of sorption water. The upper limit of the drying temperature is established, above which the thermal stability of polymers deteriorates markedly.