• Analytical Science and Technology
• /
• v.23 no.4
• /
• pp.383-388
• /
• 2010

Catalytic dissociation reaction was studied in order to transform waste plastics to oil by using noble metal supported catalysts. XRD, SEM, and GC/MSD analysis were performed to find the crystalline structure and shape, and product distribution. Generally, dissociation reaction occurs at low temperature compared to pyrolysis. Dissociation reaction has advantage of gasoline yield with respect to pyrolysis which products mainly $C_1\simC_4$. The result of dissociation reaction, gasoline was obtained much as a product. $C_5\simC_{11}$ compounds were produced as a gasoline product on Pt-zeolite among noble metal catalysts at $340^{\circ}C$. The conversion of dissociation reaction of waste plastics on the prepared catalyst was above 70% over $340^{\circ}C$.

• Analytical Science and Technology
• /
• v.13 no.1
• /
• pp.101-107
• /
• 2000

The automotive paints could be generally differentiated by color, layer sequence and chemistry of the paint layers comprising each of the topcoat and the primer system. The successful identification of hit-andrun a and traffic accidental vehicles from evidential paint fiagments is greatly facilitated with a comprehensive laboratory collection of reference paint samples and the technique for direct analysis without sample preparation. The Pyrolysis-Gas Chromatography(PGC) is a precise and reliable method for performing both quantitative and qualitative analysis of polymeric materials and forensic samples. Our Forensic Laboratory is conducting the examination and identification of 73 reference paint samples; 4 colors of each domestic automotive make that is popular in Korea, by Curie Point Pyrolyzer(JHP-3) and GC with capillary column(ultra alloy-5). This method can be used not only to compare paint traces with their suspected sources, but also to identify the type, make and model of the automotive car.

• Analytical Science and Technology
• /
• v.26 no.3
• /
• pp.190-198
• /
• 2013

Ambers have been used mostly as beads, jewelry and ornaments from ancient times and excavated as a buried artifact. When excavated, they are severely weathered to be cracked, exfoliated and disintegrated. Monitoring of changes in composition of amber according to weathering is very important for diagnosing the condition of amber and applying conservation materials and techniques. In this study, we tried to find the components of amber by analyzing amber with pyrolysis/GC/MS. The changes in the composition of pyrolzates after artificial ageing for 60 days under heat and oxygen were also observed. Abietic acid was detected as a main component of fresh amber and monoterpene, alkene, aromatic hydrocarbon were detected as major pyrolyzates. Changes with artificial ageing was estimated by comparing the peak area ratio of 23 components, and it was found that abietic acid abruptly decreased in the presence of heat and oxygen together, revealing that oxygen is a key factor to the deterioration of amber. It was also tried to understand the weathered surface of original amber gemstone based on the result of this ageing experiment.

• Carbon letters
• /
• v.22
• /
• pp.48-59
• /
• 2017

This study synthesized pure anatase carbon doped $TiO_2$ photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/$TiCl_4$. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The XRD patterns showed that the supported $TiO_2$ nanocrystals are typically anatase, polycrystalline and body-centered tetragonal in structure. The EDS and XPS results complemented one another and confirmed the presence of carbon species in or on the $TiO_2$ layer, and the XPS data suggested the substitution of titanium in $TiO_2$ by carbon. Instead of using calcination, PAN pyrolysis was used to control the carbon content, and the mesoporosity was tailored by the applied temperature. The supported $TiO_2$ nanocrystals prepared by pyrolysis at 300, 350, and $400^{\circ}C$ for 3 h on a stainless steel mesh were actual supported carbon doped $TiO_2$ nanocrystals. Thus, $PAN/DMF/TiCl_4$ offers a facile, robust sol-gel related route for preparing supported carbon doped $TiO_2$ nanocomposites.

• Analytical Science and Technology
• /
• v.24 no.4
• /
• pp.256-265
• /
• 2011

Ambers have been used as a gemstone and a religious object since the ancient times and found in several archaeological sites in Korea. To prepare an enhanced conservation measures, we surveyed the chemical and spectroscopic properties of the ambers according to the provenance. Total 14 amber samples were collected from 6 different provenances including Baltic, Chiapas, Colombian, Dominican, Fushun and Madagascar amber. Infrared (IR) spectroscopic analysis was conducted for the non-destructive examination of the amber samples. They were also analyzed with pyrolysis/GC/MS (py/GC/MS) at the pyrolysis temperature of $300^{\circ}C$ with the on-line derivatization to trimethylsilyl ester. Baltic shoulder corresponding to the absorption at $1250cm^{-1}{\sim}1150cm^{-1}$ appeared in the IR spectrum of Baltic amber. IR spectra of the other ambers also showed somewhat distinctive characteristic peaks. In py/GC/MS analysis peaks assignable to succinic acid, dehydroabietic acid and pimaric acid were detected, which are known to be the components of the amber. In the meanwhile, the presence of compounds appearing in certain amber will be applied to differentiate the provenances of amber relics if their fragments are available for the analysis. These results are expected to help the confirmation of archaeological amber relics and archaeometric interpretation of provenances and manufacturing techniques.

• Conservation Science in Museum
• /
• v.30
• /
• pp.47-70
• /
• 2023

In 2019, the first excavation survey was conducted at the Temple Site No. 4 of Yaksugok Vally in Namsan Mountain, Gyeongju to determine the original location of the headless stone Buddha statue and the structure of the temple site. The survey excavated a stone Buddha head that was confirmed in a comparative analysis to be petrologically and mineralogically identical to a headless stone seated Buddha statue found derelict nearby. Traces of gold leaf and black adhesive were found on a portion of the right side of the face of the Buddha head buried in the ground. Since it is exceedingly rare for lacquer and gilding techniques to have been applied to a large stone Buddha statue without a base layer, this study examines the gilding techniques of the time by analyzing the characteristics of the materials used. In this process, the structure of the gold foil was observed through analytical microscopy and scanning electron microscopy with energy dispersive X-ray spectrometry, and the gold (Au) component was identified. As a result of analyzing the black adhesive using pyrolysis-gas chromatograph/mass spectrometry (pyrolysis-GC/MS), pyrolysis compounds such as hydrocarbons, fatty acids, catechol, and catechol oxidation products were detected. This was identical to the characteristics identified upon analyzing lacquer collected from species of lacquer tree whose main component is urushiol. Therefore, it was confirmed that the stone Buddha head excavated from the Temple Site No. 4 of Yaksugok Valley was separated from a nearby stone seated Buddha statue, and that the gold foil was attached using lacquer sap collected from lacquer trees, which grow in Korea, China, and Japan.

• Environmental Engineering Research
• /
• v.11 no.5
• /
• pp.250-256
• /
• 2006

The combustion kinetics of poly(ethylene terephthalate) (PET) was studied by the dynamic model which accounts for the thermal decomposition of polymer at any time. The kinetic analysis was performed by a conventional nonisothermal thermogravimetric (TG) technique at several heating rates between 10 and 40 K/min in air atmosphere. The thermal decomposition of PET in air atmosphere was found to be a complex process composed of at least two stages for which kinetic values can be calculated. The combustion kinetic analysis of PET gave apparent activation energy for the first stage of $257.3{\sim}269.9\;kJ/mol$, with a value of $140.5{\sim}213.8\;kJ/mol$ for the second stage. To verify the effectiveness of the kinetic analysis method used in this work, the kinetic analysis results were compared with those of various analytical methods. The kinetic parameters were also compared with values of the pyrolysis of PET in nitrogen atmosphere.

• Journal of the Korean Society of Tobacco Science
• /
• v.29 no.2
• /
• pp.125-131
• /
• 2007

Hydrogen cyanide(HCN), formed from pyrolysis of various nitrogenous compounds such as protein, amino acids and nitrate in tobacco, is present in both the particulate phase and vapor phase of cigarette smoke. Typically the determination of HCN in cigarette smoke has been done through colorimetric and electrochemical techniques, such as fluorescence spectrometry, UV-spectrophotometry (UV), continuous flow analyzer (CFA), capillary GC-ECD and ion chromatography (IC). Most of these techniques are known to be time-consuming and some of them lack specificity or sensitivity. The available results from both our laboratory and reported literatures for 2R4F Kentucky reference cigarette, smoked under ISO condition, show a relatively wide variation ranging from 100 to 120 ug/cig of HCN. Especially, the precision and accuracy of the analytical results of HCN tend to get worse in low tar cigarettes and under intense smoking condition. In this paper, a more optimized analytical methods than previous ones are suggested. This method shows lower detection limit and has improved precision and accuracy, so it is applicable for wide tar level cigarettes under intense smoking condition as well as under ISO smoking condition. Important features of this method are improved sample collection and quantification systems such as the number of trapping units, volume, temperature and type of trapping solution. To avoid volatilization loss of HCN in analyzing mainstream smoke, it is highly recommended that pH values of trapping solutions should be maintained over 11 and cold traps should be used in collecting mainstream smoke.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2001.06a
• /
• pp.1516-1516
• /
• 2001

During the recent years, wine analysis has played an increasing role due the health benefits of phenolic ingredients in red wine [1]. On the other hand there is the need to be able to distinguish between different wine varieties. Consumers want to know if a wine is an adulterated one or if it is based on the pure grape. Producers need to certificate their wines in order to ensure compliance with legal regulations. Up to now, the attempts to investigate the origin of wines were based on high-performance liquid chromatography (HPLC), gas chromatography (GC) and pyrolysis mass spectrometry (PMS) [l,2,3]. These methods need sample pretreatment, long analysis times and therefore lack of high sample throughput. In contradiction to these techniques using near infrared spectroscopy (NIRS), no sample pretreatment is necessary and the analysis time for one sample is only about 10 seconds. Hence, a near infrared spectroscopic method is presented that allows a fast classification of wine varieties in bottled red wines. For this, the spectra of 50 bottles of Cabernet Sauvignon, Lagrein and Sangiovese (Chianti) were recorded without any sample pretreatment over a wavelength range from 1000 to 2500 nm with a resolution of 12 cm$\^$-1/. 10 scans were used for an average spectrum. In order to yield best reproducibility, wines were thermostated at 23$^{\circ}C$ and a optical layer thickness of 3 mm was used. All recorded spectra were partitioned into a calibration and validation set (70% and 30%). Finally, a 3d scatter plot of the different investigated varieties allowed to distinguish between Cabernet Sauvignon, Lagrein and Sangiovese (Chianti). Considering the short analysis times this NRS-method will be an interesting tool for the quality control of wine verification and also for experienced sommeliers.

• Journal of the Korean Society of Tobacco Science
• /
• v.22 no.2
• /
• pp.176-183
• /
• 2000

This study was conducted to compare the volatile components of lamina(cutter group) and midrib of flue-cured tobacco leaves by two analytical methods, Curie-Point pyrolysis and Purge & Trap headspace technique. The pyrolysis of lamina and midrib part of tobacco leaves was performed at the temperature of $330^{\circ}C$, $650^{\circ}C$, and $920^{\circ}C$ by Curie-Point Pyrolyzer, and 33 compounds were identified in the pyrolyzates by GC/MSD. The composition of the components identified showed a quite difference between lamina and midrib. However, the amount of the pyrolyzed products from the both of lamina and midrib was increased with temperature increase except that of acetic acid, furfural, and nicotine. The content of phenolic compounds including phenol, 4-methyl phenol, and 3-methyl phenol was higher in midrib than in lamina, while that of furan compounds such as 2,3-dihydrobenzofuran, 5-hydroxymethyl furfural, was high in lamina. Interestingly, acetamide, 2-propenamide and 3-acetoxy pyridine were not defected in the pyrolyzates of lamina. By Purge & Trap headspace technique, 28 volatile components were identified in both lamina and midrib. The composition of the identified compounds and their chromatograpic patterns also showed the complete difference between the two. The content of solanone, $\beta$-damascone, $\beta$-damascenone, and megastigmatrienones, key components of tobacco aroma, was much higher in lamina than in midrib. The results indicate that lamina contains much more carbonyl compounds known to enhance the smoke taste of cigarette, whereas midrib takes nitrogenous and phenolic compounds, which are known to cause a deteriorate effect of smoke such as irritation.