• Economic and Environmental Geology
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• v.54 no.6
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• pp.689-698
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• 2021

Since the mine reclamation scheme was implemented from 2007 in Korea, various remediation programs have been decontaminated the pollution associated with mining and 254 mines were managed to reclamation from 2011 to 2015. However, as the total amount of contaminated mine drainage has been increased due to the discovery of potential hazards and contaminated zone, more efficient and economical treatment technology is required. Therefore, in this study, the adsorption properties of arsenic was evaluated according to the adsorbents which were derived from water treatment sludge(Alum based adsorbent, ABA-500) and granular ferric hydroxide(GFH), already commercialized. The alum sludge and GFH adsorbents consisted of aluminum, silica materials and amorphous iron hydroxide, respectively. The point of zero charge of ABA-500 and GFH were 5.27 and 6.72, respectively. The result of the analysis of BET revealed that the specific surface area of GFH(257 m²·g^-1) was larger than ABA-500(126~136 m²·g^-1) and all the adsorbents were mesoporous materials inferred from N₂ adsorption-desorption isotherm. The adsorption capacity of adsorbents was compared with the batch experiments that were performed at different reaction times, pH, temperature and initial concentrations of arsenic. As a result of kinetic study, it was confirmed that arsenic was adsorbed rapidly in the order of GFH, ABA-500(granule) and ABA-500(3mm). The adsorption kinetics were fitted to the pseudo-second-order kinetic model for all three adsorbents. The amount of adsorbed arsenic was increased with low pH and high temperature regardless of adsorbents. When the adsorbents reacted at different initial concentrations of arsenic in an hour, ABA-500(granule) and GFH could remove the arsenic below the standard of drinking water if the concentration was below 0.2 mg·g^-1 and 1 mg·g^-1, respectively. The results suggested that the ABA-500(granule), a low-cost adsorbent, had the potential to field application at low contaminated mine drainage.

• Analytical Science and Technology
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• v.34 no.6
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• pp.259-266
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• 2021

Cannabis (Marijuana) is one of the most widely used drugs in the world, and its distribution has been controlled in South Korea since 1976. Identification of 11-nor-Δ⁹-carboxy-tetrahydrocannabinol (THCCOOH) in urine can provide important proof of cannabis use, and it is considered scientific evidence in the forensic field. In this study, we describe a simultaneous quantitative method for identifying THCCOOH and THCCOOH-glucuronide in urine, using simple liquid-liquid extraction (LLE), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). THCCOOH-D₃ and THCCOOH-glucuronide-D₃ were used as internal standards. Validation results of the matrix effect, as well as recovery, linearity, precision, accuracy, process efficiency, and stability were all satisfactory. No carryover, endogenous or exogenous interferences were observed. The limit of detection (LOD) of THCCOOH and THCCOOH-glucuronide were 0.3 and 0.2 ng/mL, respectively. The developed method was applied to 28 authentic human urine samples that tested positive in immunoassay screening and gas chromatography/mass spectrometry (GC/MS) tests. The ranges of concentrations of THCCOOH and THCCOOH-glucuronide in the samples were less than LOQ~266.90 ng/mL and 6.43~2133.03 ng/mL, respectively. The concentrations of THCCOOH-glucuronide were higher than those of THCCOOH in all samples. This method can be effectively and successfully applied for the confirmation of cannabinoid use in human urine samples in the forensic field.

• Analytical Science and Technology
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• v.35 no.3
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• pp.136-142
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• 2022

According to media reports, the carcasses of euthanized abandoned dogs were processed at high temperature and pressure to make powder, and then used as feed materials (meat and bone meal), raising the possibility of residuals in the feed of the anesthetic ketamine and dexmedetomidine used for euthanasia. Therefore, a simultaneous analysis method using QuEChERS combined with high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry was developed for rapid residue analysis. The method developed in this study exhibited linearity of 0.999 and higher. Selectivity was evaluated by analyzing blank and spiked samples at the limit of quantification. The MRM chromatograms of blank samples were compared with those of spiked samples with the analyte, and there were no interferences at the respective retention times of ketamine and dexmedetomidine. The detection and quantitation limits of the instrument were 0.6 ㎍/L and 2 ㎍/L, respectively. The limit of quantitation for the method was 10 ㎍/kg. The results of the recovery test on meat and bone meal, meat meal, and pet food showed ketamine in the range of 80.48-98.63 % with less than 5.00 % RSD, and dexmedetomidine in the range of 72.75-93.00 % with less than 4.83 % RSD. As a result of collecting and analyzing six feeds, such as meat and bone meal, prepared at the time the raw material was distributed, 10.8 ㎍/kg of ketamine was detected in one sample of meat and bone meal, while dexmedetomidine was found to have a concentration below the limit of quantitation. It was confirmed that the detected sample was distributed before the safety issue was known, and thereafter, all the meat and bone meal made with the carcasses of euthanized abandoned dogs was recalled and completely discarded. To ensure the safety of the meat and bone meal, 32 samples of the meat and bone meal as well as compound feed were collected, and additional residue investigations were conducted for ketamine and dexmedetomidine. As a result of the analysis, no component was detected. However, through this investigation, it was confirmed that some animal drugs, such as anesthetics, can remain without decomposition even at high temperature and pressure; therefore, there is a need for further investigation of other potentially hazardous substances not controlled in the feed.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.1-9
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• 2022

An estuary is an area where a freshwater river or stream meets the ocean. Even before the importance of the value of estuaries was recognized, the estuary was lost because of large-scale conversion by draining, filling, damming, and dredging. In South Korea, 643 estuaries are located, and the total area is 3,248,300 ha, accounting for 32.5% of the total area of South Korea. Over 35% of Korean estuaries are closed estuaries which are only temporally connected with the sea, either permanently or periodically. Since 2008, in order to preserve the estuary ecosystem and solve major issues in the estuary by accumulating knowledge about the estuarine ecosystem, the Ministry of Environment of Republic of Korea has been conducting the "Estuarine Ecosystem Monitoring and Assessment Project". At 668 sites of 325 estuaries, epilithic diatom, benthic macroinvertebrate, fish, and vegetation are investigated, and the habitat condition of each site is evaluated using the newly developed biotic index. More than 100 researchers annually record 2,097 species of estuaries according to the standardized survey guidelines over the past 14 years and provide strictly managed data necessary for establishing estuaries conservation policies. As a result of bibliometric analysis of 1,195 research articles related to the monitoring and assessment of the estuarine ecosystem, research on pollutants such as heavy metals and sediment control have recently been conducted. "Estuarine Ecosystem Monitoring and Assessment Project" is an ecological monitoring type of long-term mandated monitoring that is usually focused on identifying trends. Although it is difficult to identify the mechanism influencing a change in an ecosystem through long-term mandated monitoring, providing empirical data for supporting evidence-based policy, decision-making, and the management of ecosystems. In order to increase the efficiency of the project, research to investigate the relationship between sediments and pollutants and organisms can be conducted at specific estuaries or sites to compensate for the shortcomings of mandatory monitoring.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.319-331
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• 2023

Aminoglycoside antibiotics, also known as aminoglycosides (AGs), are veterinary drugs effective against a wide range of gram-negative and gram-positive bacteria. Owing to their recent use in cultured meats, it has become essential to establish an analytical method for safety management. AGs are highly polar compounds, and ion-pair reagents (IPRs) are used to ensure component separation. Owing to the high possibility of potential mechanical problems resulting from IPR addition to the mobile phase, an analytical method in which IPRs are added directly to the vial was explored. In this study, methods for analyzing 10 AGs via liquid chromatography-tandem mass spectrometry (LC-MS/MS) with the addition of two IPRs were validated for selectivity, detection limit, quantitation limit, recovery, and precision. The detection limit was 0.0001-0.0038 mg/kg, the quantification limit was 0.004-0.011 mg/kg, and the linearity (R²) within the concentration range of 0.01-0.5 mg/kg was over 0.99. Recovery and precision (expressed as relative standard deviation) evaluated in the two matrices (beef and cell culture media) ranged from 70.7% to 120.6% and 0.2% to 24.7%, respectively. The validated AG analytical method was then applied to 15 meats prepared from chicken, beef, and pork, and 6 culture media and additives used in cultured meat. No AGs were detected in any of the 15 meats distributed in Korea; however, streptomycin and dihydrostreptomycin were detected at levels ranging from 695.85 to 1152.71 mg/kg and 6.35 to 11.11 mg/kg, respectively, in the culture media additives. The LC-MS/MS method coupled with direct addition of IPRs to the vial can provide useful basic data for AG analysis and safety evaluation of meats as well as culture media and additives for cultured meats.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.3
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• pp.5-18
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• 2024

Chemical oxygen demand (COD), an organic material measurement index, has a limit to the management of the total amount of all organic materials including non-degradable organic materials due to low oxidation rate. So total organic carbon (TOC) that can measure organic materials more accurately is introduced and used as a measurement index. Several environmental companies including company A in Gyeonggi-do dilute raw wastewater first and then treats it with chemicals. And an activated carbon is used at the rear stage to treat total organic carbon even though various treatment processes can be applied to reduce TOC in wastewater. There are some problems such as use of a lot of diluting water and generation of an excessive amount of sludge, so it is urgent to come up with an alternative plan. Therefore, in this study, an application experiment was conducted on two different methods for improving the TOC reduction efficiency of waste water from Company A. The first method is the evaluation of the substitution potential of powered activated carbon(PAC), an adsorbent currently used, by manufacturing cellulose-based graphene like carbon (CGLC). This first study showed that CGLC had about 10% higher TOC adsorption efficiency than commercial PAC, showing the possibility of being applied as an alternative adsorbent for PAC in water treatment sites. The second method relates to the removal of TOC by sulfate radials produced by persulfate (PS) activation. Two activation methods were applied: using CGLC and PAC as carbon-based catalyst and using the high temperature of wastewater for PS activation. As a result of using PAC and CGLC as PS activation materials, the TOC removal rate was lower than the adsorption amount of TOC by CGLC and PAC due to excessive chlorine ions present in the real wastewater. However, as a result of using the high water temperature (55~60℃) of the field wastewater for PS activation, it showed a much greater TOC removal efficiency than PAC alone, CGLC alone, and using a carbon-based catalyst for PS activation. When PS was injected more than 0.5%, it showed a TOC removal efficiency of 95% or more within 24 hr. In addition, when PS was injected more than 0.3%, the TOC concentration could be lowered to less than 75 ppm, which is the wastewater discharge standard applied to company A. When these results were summarized, raw wastewater of high temperature can be treated with a simple process of only adding of PS and discharged by treating TOC below the wastewater discharge standard applied to company A.

• Journal of Environmental Science International
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• v.4 no.2
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• pp.223-232
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• 1995

New two macrocyclic compounds using as carriers of liquid emulsion menbrame, have been synthesized. These reuslts provide evidance for the usefulness of the theory in designing the systems. The efficiency of selective transport for heavy metal ions have been discussed from the membrane systems that make use of $SCN^-$,<>,$I^-$,CN- and $Cl^-$ ion as co-anions in source phase and make use of $S_2O_3^{2-}$ and $P_2O_7^{4-}$ ion as receiving phase, respectively. The transport rate of M(II) was highest when a maximum amount of the M(II) in the source phase was present as$Cd(SCN)_2$$(P[SCN^-]= 0.40M)$, $Hg(SCN)_2([SCN^-]=0.40M)$ and Pd(CN)$([CN^-]= 0.40M)$. The Cd(II) and Pb(II) over each competitive cations were well transprted with 0.3M-S2032- and 0.3M-P2O74-, respectively in the receiving phase. Results of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsion system. First one must effective extraction of the $M^{n+}$ into the toluene systems. The effectiveness of this extraction is the greatest if locK for $M^{n+}$macrocycle interaction is large and if the macrocycle is very insoluble in the aqueous phase. Second, the ratio of the locK values (or Mn+-receiving phase ($S_2O_3^{2-}$- or $P_2O_7^{4-}$) to $M^{n+}$-macrocycle (($L_1$이나 $L_2$) interaction must be large enough to ensure quantitative stripping of Mn+(($Cd^{2+}$,$Pb^{2+}$)at the toluene receiving Phase interface. $L_1$(3.5-benzo-10,13,18,21-tetraoxa-1,7,diazabicyclo(8,5,5) eicosan) forms a stable ($Cd^{2+}$ and >,$Pb^{2+}$ complexes and $L_1$ is very insoluble in water and its $Cd^{2+}$ and >,$Pb^{2+}$ complex is considerably less stable than $Cd^{2+}$-(S2O3)22- and $Pd^{2+}-P_2O_7^{4-}$ complexes. On the other hand, the stability of the $Hg^{2+}$)+-$L_1$( complex exceed that of the $Hg^{2+}$- (S2O3)22- and Hg2+-P2O74-, and the distribution coefficient of $L_2$(5,8,15,18,23,26-hexaoxa-1,12- diazabicyclo-(10,8,8) octacosane) is much smaller than that of $L_1$. Therefore, the partitioning of Lr is favored by the aqueous receiving Phase, and little heavy metal ions transport is seen despite the large logK for $Hg^{2+}$+-$L_1$ and $Mn^+$($Cd^{2+}$+, $Pb^{2+}$+ and $Hg^{2+}$)-$L_2$ interactions. Key Words : macrocycles, transport, heavy metal, co-anion, source phase, receiveing, complex separation, interaction, destribution coefficient.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.325-329
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• 2004

Purpose: Usefulness of mouse liver S9 fraction was evaluated for the measurement of the metabolites in the in vitro metabolism study of $^{18}F$-labeled radiotracers. Materials and Methods: Mouse liver S9 fraction was isolated at au early step in the course of microsome preparation. The in vitro metabolism studies were tarried out by incubating a mixture containing the radiotracer, S9 fraction and NADPH at $37^{\ciirc}C$, and an aliquot of the mixture was analyzed at the indicated time points by radio-TLC. Metabolic defluorination was further confirmed by the incubation with calcium phosphate, a bone mimic. Results: The radiotracer $[^{18}F]1$ underwent metabolic defluorination within 15 min, which was consistent with the results of the in vivo method and the in vitro method using microsome. Radiotracer $[^{18}F]2$ was metabolized to three metabolites including $4-[^{18}F]fluorobenzoic$ acid within 60 min. It is likely that the one of these metabolites at the origin of radio-TLC was identical with the one that obtained from the in vivo and in vitro (microsome) method. Compared with the in vitro method using microsome, the method using S9 fraction gave a similar pattern of the metabolites but with a different ratio, which can be explained by the presence of cytosol in the S9 fraction. Conclusion: These results suggest that the findings of the in vitro metabolism studies using S9 fraction can reflect the in vivo metabolism of novel radiotracers in the liver. Moreover, this method can be used as a tool to determine metabolic defluorination along with calcium phosphate absorption method.

• (The) Research of the performance art and culture
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• no.23
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• pp.281-312
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• 2011

The aim of this study is to examine various life conditions of actors of Joseon periods in unofficial historical stories. Yadam Literature(Korean unofficial historical stories) had been collected Sadaebu(the past Korean nobility and Confucian intelligentsia) among the people that stories had been handed down orally. and they had been wrote them. So Yadam Literature was heterozygous between the folk culture and the ruling class. And it was mixed and adapted legends and folktales, adding literary imagination. had a decisive role to cultivating novel that owed much to prosaic inspiration during A. D. 18~19. Besides, set a high value on excellent novel itself. Yadam Literature had a verisimilitude because it described a contemporary reality as it was founded on freely prosaic inspiration. In those days, so called Suchok and Seunggwangdae had performed Uhee(a comic theatrical performance) in Joseon periods. Suchok was the lowest class of people and Seunggwangdae was performing Buddhist monk in that time. Uhee had performed three kinds of comedies. One satirized and insinuated kings. Other satirized corrupt officials, too. Another had mimic everything. It is famous at that time as a king knew repertoire. Confucian scholars very were fond of Uhee in those ages. Because they favored a criticism of Uhee's satire. They thought that it gave people good lesson or instruction. Heri Bergson said that comic and Humor included lesson. At that time, those thought were universal in the world whether east or west. At any rate, I classify six kinds of types Uhee in Yadam Literature. First, satirizing and accusing corrupt officials. Second, an actor who use a satire in order to appeal secure a government position of his lord to a king. Third, shamans and actors who use a satire in order to appeal sufferings themselves to a king. Forth, actors and performing Buddhist monks that skillfully mimic anything. Fifth, describing actor's extremely miserable life. Sixth, wit and humor of actors. The contents of Uhee were various. Korean traditional actors adeptly dealt with aspects comic of wit, satire, humor, etc. Sometimes they used changeable transition them. By doing that, a great number of people enjoyed fully the sense of freedom. Korean traditional actors were the lowest class of people. They had lived extremely miserable life. But they had been exist as actions, interactions, and relationship in society those days. they were not only open to people, but also might foster community to peoples.