• Analytical Science and Technology
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• v.37 no.1
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• pp.25-38
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• 2024

The study aimed to investigate a novel approach by utilizing liquid chromatography (LC) and liquid chromatography-mass spectrometry (LC-MS) to separate, identify and characterize very nominal quantities of degradation products (DPs) of balsalazide along with its process related impurities without isolation from their reaction mixtures. The impurities along with balsalazide were resolved on spherisorb ODS2 (250×4.6 mm, 5.0 ㎛) column at room temperature using 0.2 M sodium acetate solution at pH 4.5 and methanol in the ratio of 55:45 (v/v) as mobile phase pumped isocratically at 1.0 mL/min as mobile phase and UV detection at 255 nm. The method shows sensitive detection limit of 0.003 ㎍/mL, 0.015 ㎍/mL and 0.009 ㎍/mL respectively for impurity 1, 2 and 3 with calibration curve liner in the range of 50-300 ㎍/mL for balsalazide and 0.05-0.30 for its impurities. The balsalazide pure compound was subjected to stress studies and a total of four degradation products (DPs) were formed during the stress study and all the DPs were characterized with the help of their fragmentation pattern and the masses obtained upon LC-MS/MS. The DPs were identified as 3-({4-[(E)-(4-hydroxyphenyl) diazenyl]benzoyl}amino)propanoic acid (DP 1), 4-[(E)-(4-hydroxyphenyl)diazenyl] benzamide (DP 2), 5-[(E)-(4-carbamoylphenyl)diazenyl]-2-hydroxybenzoic acid (DP 3) and 3-({4-[(E)-phenyldiazenyl]benzoyl}amino)propanoic acid (DP 4). Based on findings, it was concluded that, the proposed method was successfully applicable for routine analysis of balsalazide and its process related impurities in pure drug and formulations and also applicable for identification of known and unknown impurities of balsalazide.

• Journal of Korean Society for Quality Management
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• v.34 no.3
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• pp.19-30
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• 2006

For highly reliable products, it is difficult to assess the lifetime of the products with traditional life tests. Accordingly, a recent approach is to observe the performance degradation of product during the test rather than regular failure time. This study compares performances of three methods(i.e. the approximation, analytical and numerical methods) to estimate the parameters and quantiles of the lifetime when the time-to-failure distribution follows Weibull and lognormal distributions under a random coefficient degradation rate model. Numerical experiments are also conducted to investigate the effects of model error such as measurements in a random coefficient model.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.445-457
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• 2000

This study was carried out comparing with ozone oxidation and photocatalytic degradation for removal of geosmin. In the change of pH, Ozonation, UV-Germicidal lamp and Halogen lamp irradiation and Halogen $lamp/TiO_2$ Powder was very slowly changing, but UV-Germicidal $lamp/TiO_2$ Powder was rapidly changed from 7.0 to 7.7 until 300min of irradiation time, and varied a little after. Geosmin degradation ratio was as following, UV-Germicidal $lamp/TiO_2$ $Powder(200mg/L){\geq}O_3$ > UV-Germicidal $lamp/TiO_2$ $Pw(100mg/L)$ > UV-Germicidal lamp > Halogen lamp. The result of investigation of generated by-products were 3-Heptanone, two sort of aldehydes and three sort of alcohols by ozonation. But It was not generated by photocatalytic degradation.

• Journal of Hydrogen and New Energy
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• v.19 no.1
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• pp.56-63
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• 2008

In this study, thermochemical degradation of hemicellulose by Acetone-Solvolysis, the effects of reaction temperature, conversion yield, degradation properties and degradation products were investigated. Experiments were performed in a tube reactor by varying reaction temperature from $200{\circ}C$ to $400{\circ}C$ at 40 min of reaction time. The liquid products from pyrolysis-liquefaction of hemicellulose contained various kinds of ketones. ketones, as 4-methyl-3-penten-2-one, 3-methylene-2-pentanone, 22,6-dimethyl-2, 5-heptadien-4-one, 4-methyl-2-pentanone, 5-methyl-2-hexanone, 3,5,5-trimethyl-2-cyclohexen-1-one, and bezenes. as 1,4-dimethylbenzene, 1-methyl-2-(1-methylethyl)-benzene, 1,4-dimethyl-2-(2-methylpropyl)benzene, 4-secbutyl-ethyl benzene, could be used as high-octane-value fuels and fuel additives. Combustion heating value of liquid products from thermochemical conversion processes of hemicellulose was in the range of $6,680{\sim}7,170cal/g$. After 40min of reaction at $400{\circ}C$ in Acetone-Solvolysis of hemicellulose, the energy yield and mass yield was as high as 72.2% and 41.2g oil/100g raw material, respectively.

• Journal of Hydrogen and New Energy
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• v.15 no.4
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• pp.333-340
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• 2004

In this study, thermochemical degradation by pyrolysis-liquefaction of cellulose, the effects of reaction time, reaction temperature, conversion yield, degradation properties and degradation products were investigated . Experiments were performed in a tube reactor by varying reaction time from 20 to 80 min at $200{\sim}500^\circ{C}$. Combustion heating value of liquid products from thermochemical conversion processes of cellulose was in the range of 6,920~6,960cal/g. After 40min of reaction at $400^\circ{C}$ in pyrolysis-liquefaction of cellulose, the energy yield and mass yield was as high as 54.3% and 34.0g oil/100g raw material, respectively. The liquid products from pyrolysis-liquefaction of cellulose contained various kinds of ketones, phenols and furans. ketones and furans could be used as high-octane-value fuels and fuel additives. However, phenols are not valuable as fuels.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.86-91
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• 2008

Dicamba(3,6-dichloro-2-methoxybenzoic acid) is used to control for pre and post-emergence of annual and perennial broad-leaf weeds. It is very soluble in water and highly mobile, acidic herbicide. So it is easily moved and detected in groundwater. Zerovalent iron(ZVI) has been used for the reductive degradation of certain compounds through amination of nitro-substituted compounds and dechlorination of chloro-substituted compounds. In this study, we investigated the potential of ZVI for the oxidative degradation of dicamba in water. The degradation rate of dicamba by ZVI was more rapidly increased in pH 3.0 than pH 5.0 solution. The degradation percentage of dicamba was increased with increasing amount of ZVI from 0.05% to 1.0%(w/v) and reached above 90% within 3 hours of reaction. As a result of identification by GC-MS after derivatization with diazomethane, we obtained three degradation products of dicamba by ZVI. They were identified 4-hydroxy dicamba or 5-hydroxy dicamba, 4,5-dihydroxy dicamba and 3,6-dichloro-2-methoxyphenol. 4-Hydroxy dicamba or 5-hydroxy dicamba and 4,5-dihydroxy dicamba are hydroxylation products of dicamba. 3,6-dichloro-2-methoxyphenol is hydroxyl group substituted compound instead of carboxyl group in dicamba. We also confirmed the same degradation products of dicamba in the Fenton reaction which is one of oxidation processes using ferric sulfate and hydrogen peroxide. But we could not find out the dechlorinated degradation products of dicamba by ZVI.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.1
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• pp.61-73
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• 2020

Tetracycline is one of the most commonly used antibiotics in domestic and foreign livestock industries to suppress the growth of pathogens. Tetracycline has been reported as a non-biodegradable compound. Therefore it has been not completely removed in the sewage treatment process. In this study, tetracycline was degraded using liquid ferrate (VI). Based on these experiments, the optimal water condition (pH and water temperature) were selected, appropriate liquid ferrate (VI) dosage was calculated, and finally the degradation pathway was estimated with the intermediate products detected by LC/MS/MS. All degradation experiments were completed within 30 seconds and the optimal condition was obtained in basic condition (pH 10) at room temperature (20℃). And the appropriate molar ratio between tetracycline and liquid ferrate (VI) was 12.5:1. Finally, 12 intermediate products were detected with LC/MS/MS and the degradation pathways and the degradation pathways and proposed the degradation pathways.

• Journal of Korean Society for Quality Management
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• v.32 no.1
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• pp.113-129
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• 2004

The reliability of the product can be improved by making the product less sensitive to noises. Especially, it Is important to make products robust against various noise factors encountered in production and field environments. In this paper, the phenomenon of degradation assumes a simple random coefficient degradation model to present analysis procedures of degradation data for robust experimental design. To alleviate weak points of previous studies, such as Taguchi's, Wasserman's, and pseudo failure time methods, novel techniques for analysis of degradation data using the cross array that regards amount of degradation as a dynamic characteristic for time are proposed. Analysis approach for degradation data using robust experimental design are classified by assumptions on parametric or nonparametric degradation rate(or slope). Also, a simulation study demonstrates the superiority of proposed methods over some previous works.

• Journal of Hydrogen and New Energy
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• v.16 no.2
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• pp.159-169
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• 2005

Cellulose, consisted of 45 wt% in wood, is usable as fuels and heavy oil additives if depolymerized to monomer unit, because the chemical structures are similar to high octane materials found in gasoline. In this study, thermochemical degradation by solvolysis reaction of cellulose such as the effect of reaction temperature, reaction time and type of solvent on conversion yield and degradation products were investigated. It was found that the effectiveness of the solvent on the sovolysis reaction was as follows; acetone>n-butanol>tetralin. When acetone was used as a solvent, the highest cellulose conversion was observed to be 91.8% at 500$^{\circ}C$, 40min. Combustion heating value of liquid products from thermochemical conversion processes was in the range of 7,330${\sim}$7,410cal/g. The energy yield and mass yield in acetone-solvolysis of cellulose was as high as 66.8% and 37.0 g oil/100g raw material after 40min of reaction at 400$^{\circ}C$. Various aliphatic and aromatic compounds were detected in the cellulose solvolysis products. The major components of the solvolysis products, that could be used as fuel, were mesityl oxide, mesitylene, isophorone.

• Journal of the Korean Wood Science and Technology
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• v.45 no.2
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• pp.168-181
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• 2017

Whole cell of Phanerochaete chrysosporium with reducing agent was applied to verify the degradation mechanism of aromatic compounds derived from lignin precisely. Unlike the free-reducing agent experiment, various degraded products of aromatic compounds were detected under the fungal treatment. Our results suggested that demethoxylation, $C_{\alpha}$ oxidation and ring cleavage of aromatic compounds occurred under the catabolic system of P. chrysosporium. After that, degraded products stimulated the primary metabolism of fungus, so succinic acid was ultimately main degradation product of lignin derived-aromatic compounds. Especially, hydroquinone was detected as final intermediate in the degradation of aromatics and production of succinic acid. In conclusions, P. chrysosporium has an unique catabolic metabolism related to the production of succinic acid from lignin derived-aromatic compounds, which was meaningful in terms of lignin valorization.