• Korean Journal of Environmental Agriculture
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• v.10 no.2
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• pp.149-157
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• 1991

In order to elucidate the possible change in the non-extractable bound residue of TCAB(3,3' 4,4' - tetrachloroazobenzene) in soil as a function of aging period, uniformly ring-labelled $^{14}C-TCAB$ was treated to soil(organic matter : 1.8%), and aged for 3, 6, 9, 12 and 15 months at $21{\pm}1^{\circ}C$, respectively. $^{14}CO_2$ evolution and volatilization loss during the aging were negligible. The amounts of non-extractable bound residue of TCAB increased gradually from 7.55% in 3-month aging to 19.32% in 15-month aging. Partition data suggested no formation of polar groups in the chemical structure of TCAB. Most of $^{14}C-radioactivity$ of bound residues was present in humin in the range of 50.52 to 58.93%. The fact that the number of microorganisms in soil decreased relative to the control suggested no chance of their involvement in the formation of non-extractable bound residues. Accordingly, the increase in the non-extractable bound residue of TCAB in soil with aging period is believed to be due to the transformation of the trans isomer to the cis one which is more polar and more adsorptive than the former.

• Applied Biological Chemistry
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• v.21 no.2
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• pp.71-80
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• 1978

In an attempt to elucidate the fate of 3,4-DCA and TCAB in various French soils, uniformly $^{14}C-ring-labeled$ 3,4-DCA and TCAB mere utilized and the following results obtained. 1) The rate of breakdown of $^{14}C-3,4-DCA$ into $^{14}CO_2$ was relatively higher in the early stage than that in the later stage. In 6 months of incubation in alkaline soil (pH 7.9), the rate was as high as 6.5% at dose 1 (1.5 ppm) and as low as 1.92% at dose 2(94 ppm), whereas in organic acid soil (pH 5.5) the rate was 4.91% at dose 1 and 4.24% at dose 2, respectively, without making any great difference between the two levels. 2) At dose 1, 47.70% of the initial radioactivity of $^{14}C-3,4-DCA$ was bound to soil in organic acid soil and 29.49% bound in alkaline soil, whereas at dose 2, 38.40% in organic acid soil and 20.30% in alkaline soil, respectively. 3) The amount of formation of $^{14}C-TCAB$ from $^{14}C-3,4-DCA$ seems to depend largely on the concentration of 3,4-DCA applied rather than on soil types. At dose 2, the amount was 50% of the total radioactivity extracted in organic acid soil and 30% in alkaline soil, corresponding to 1.8% and 1.4% of the initial radioactivity applied to soil, respectively. Cis-TCAB also seemed to be formed at dose 2 in both soils. Meanwhile, at dose 1, even though $^{14}C-TCAB$ was detected in trace on tlc and glc in both soils, the amount does not exceed 2 to 3% of the radioactivity extracted, corresponding to 0.05 to 0.1% of the initial radioactivity. 4) The rate of breakdown of $^{14}C-TCAB$ into $^{14}CO_2$ ranged from 0.05 to 0.20% in all the four soils. Most of the applied $^{14}C-TCAB$ remained intact after 3 months, not producing any detectable metabolites. 5) The fact that much more $^{14}C-TCAB$ was adsorbed to alkaline soil than to the other soils strongly indicates that in alkaline condition trans-isomer was converted tocisisomer which has the higher adsorption affinity than the former.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.279-286
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• 1991

In order to investigate the possibility of the microbial degradation of the persistent pollutant 3, 3', 4, 4'-tetrachloroazobenzene (TCAB) in our environment, four strains of microorganisms were isolated from industrial wastes by the enrichment technique. They were identified as Achromobacter group VD, Pseudomonas alcaligenes, Moraxella spp., and Alcaligenes faecalis, respectively. These microorganisms utilized TCAB as a sole carbon source in the $MM_2$ salt medium.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.109-116
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• 1977

Much attention has been paid to the fact that quite a few herbicides such as phenylcarbamates, phenylureas, and acylanilides form azo compounds known as carcinogens by virtue of the microoranisms in soil. In consequence, many investigators synthesized. TCAB, an azo compound, starting from 3,4-dichloronitrobenzene for the related studies. However, the authors were under the necessity of synthesizing $^{14}C-ring-labeled$ TCAB from $^{14}C-ring-labeled$ 3,4-DCA available, in addition to making up for the disadvantage of dechlorination in the reduction of 3,4-dichloronitrobenzene. The new method is as follows:TCAB, $^{14}C-ring-labeled$ and non-labeled, was produced by aerial oxidation of 3,4-DCA catalyzed by CuCl with pyridine as solvent at $60^{\circ}C$ for 5-12 hrs, giving 80.2% yield. The procedure forpurification was described in detail. The identities of TCAB isomers were confirmed by means of autoradiography, TLC, GLC, IR, and MS.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.299-306
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• 1991

When $[U-^{14}C]$ 3,3', 4,4'-tetrachloroazobenzene$([U-^{14}C]\;TCAB)$ was added to the $MM_2$ medium as a sole carbon source for the isolated microorganisms and incubated, some radioactive metabolites were detected by autoradiography. No $^{14}CO_2$ was evolved from $[U-^{14}C]\;TCAB$ which was added as a sole carbon source to an organic matter-free soil inoculated by the isolates, wetted with the $MM_2$ salt medium, and incubated at $30^{\circ}C$. One of the metabolites in pure culture of Achromobacter group VD, which was isolated and identified, was tentatively identified as a compound of m/z 250 by means of GC/MS. The possible pathways for its formation are thought to include dechlorination from the TCAB structure, hydroxylation, ortho fission of the two benzene rings, and reduction of the resulting carboxyl group.

• Korean Journal of Environmental Agriculture
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• v.12 no.1
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• pp.9-17
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• 1993

The leaching behavior of $^{14}C-carbofuran$, $^{14}C-bentazon$, and $^{14}C-3,3,4,4'-tetrachloroazobenzene(TCAB)$ in the forms of freshly treated, 3-month-aged, and 6-month-aged residues, respectively, was investigated in a loamy soil column system. The degradation and mobility of pesticides in soil and the possibility of the contamination of groundwater were followed by this approach: The ambient temperature of $15{\pm}2^{\circ}C$, irrigation by the constant-head method on soil columns, and leaching with 1332 ml of simulated precipitation during 90 days. While the fresh residues of $^{14}C-carbofuran$ and $^{14}C-bentazon$ were very mobile, the aged ones were remarkably reduced in their mobility. Fresh and aged residues of $^{14}C-TCAB$ were very immobile, instead. 3-Keto carbofuran phenol(2,3-dihydro-2,2-dimethyl-3-oxo-7-benzofuranol) was the major degradation product present in the leachate from the soil column containing freshly treated $^{14}C-carbofuran$, while no metabolites could be detected in the leachates from the columns containing $^{14}C-bentazon$ or $^{14}C-TCAB$.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.27-32
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• 1987

To isolate and identify degradation products of propanil in solution which propanil concentration was 2000ppm with a certain temperature, degradation products and pathway were investigated every 2 weeks for 12 weeks. Extracted mixture was developed with benzene on TLC plate, and Rf values of isolated DCA and TCAB were 0.65 and 0.94 respectively. At the GC analysis, propanil and its degradation products could seperate at the column temperature $200^{\circ}C$, but in order to more good resolution, the column temperature of DCA and TCAB was $140^{\circ}C$ and $250^{\circ}C$ respectively. Functional group of OCA was determined by IR spectrum $3400cm^{-1}$ and $800cm^{-1}$. Proton peaks of OCA were NMR spectrum $6.7{\delta}$ and $3.7{\delta}$. As the results, the major degradation products of propanil in solution were seperated on TLC plate, and thus identified by the analysis of GC, IR and NMR. Proposed degradation pathway of propanil in solution was from DCA to TCAB.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.33-39
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• 1987

In order to study the degradation pattern of propanil in solution, the environmental factors such as temperature, pH and UV irradiation effect on propanil degradation were investigated. The degradation of propanil in solution was more rapid in high temperature than in low. The production amount of DCA was increased in high temperature, and then was decreased in a certain period of time because of conversion to TCAB, but the concentration of TCAB was maintained without more degradation. Propanil was rapidly hydrolyzed in alkaline solution as well as in strong acidic solution. Degradation product, DCA was rapidly produced and condensed to TCAB in strong acidic and alkaline condition. On exposur to ultraviolet light, 90% of original propanil was degraded within 20minutes, 0.3 ppm of DCA was produced in 10 minutes, and maintained the concentration throughout irradiation times.

• Applied Biological Chemistry
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• v.21 no.3
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• pp.197-203
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• 1978

In order to investigate mechanisms related to the microbial degradation of 3,4-dichloroaniline, it was incubated with a soil fungus, Chaetomium globosum and the following results were obtained. (1) 3,4-Dichloroacetanilide turned out to be the major metabolite, indicating that acetylation is the major scheme. (2) The presence of trace amounts of 3,4-dichloronitrobenzene, 3,3', 4,4'-tetrachloroazo-benzene, 3,4-dichloroaniline is suggestive of the aromatic amine oxidation as the minor pathway. (3) Other metabolites with m/e 112, 114, and 279 were also isolated, but their identities are under investigation. (4) Dechlorination occurring during incubation indicates the possibility of forming hydroxylated and other metabolites.