• Elastomers and Composites
• /
• 제48권3호
• /
• pp.181-189
• /
• 2013

비충전, 카본블랙 충전, 그리고 실리카 충전 천연고무(NR) 복합체를 원형 변형 상태로 $60-90^{\circ}C$에서 노화시켜 회복 거동을 조사하였다. 시험편은 공기와 물을 매일 교대로 교체하는 교매질 시스템 하에서 노화시켰다. 충전시스템에 따른 회복률의 순서는 비보강 > 실리카 보강 > 카본블랙 보강 순이었다. 공기에서 물로 교체하는 교매질 시스템에서 노화된 시험편의 회복률이 물에서 공기로 교체하는 교매질 시스템에서 노화된 시험편의 회복률보다 더 컸다. 최초 노화 매질은 변형 정도에 지배적으로 영향을 끼쳤다.

• Bulletin of the Korean Chemical Society
• /
• 제24권12호
• /
• pp.1731-1736
• /
• 2003

The reaction of ${\alpha}$-Benzilmonoxime with palladium(II) produces a green complex in triton X-100 micellar media. Palladium has been determined using zero and first derivative spectrophotometric methods. The absorbances of Pd(II)- ${\alpha}$--benzilmonoxime complex at 441.8 and 677.0 nm in 0.10 M perchloric acid solution were monitored and linear working ranges of 0.3-12.0 and 0.7-20 ${\mu}$g mL$^{-1}$ with detection limits of 0.07 and 0.10 ${\mu}$g $mL^-1$ were obtained, respectively. Also, recoveries in the range of 92.8 to 100.1% and relative standard deviations in the range of 0.4 to 7.1% were obtained. First derivative spectrophotometry has also been applied for palladium determination under the optimum condition. The linear dynamic range of 0.2-24.0 ${\mu}$g $mL^{-1}$ palladium with relative standard deviations of 0.6-6.9% and recoveries in the range of 94.9-102.5% has been obtained by first derivative spectrophotometry. The method shows high selectivity because of the high concentration of acid used, which prevents formation of complexes of ${\alpha}$--benzilmonoxime with the other cations. The palladium complex formed was stable at least one day. The method was successfully applied to the determination of palladium in some synthetic palladium alloys and palladium-charcoal powder.

• Mass Spectrometry Letters
• /
• 제11권4호
• /
• pp.82-89
• /
• 2020

A systematic isolation and characterization study for Cassia auriculata (CA) seeds resulted in identifying antidiabetic compounds 1,3,8-trihydroxyanthraquinone and quercetin, quercetin-3-O-rutinoside, gallic acid, caffeic acid, ferulic acid, and ellagic acid. The ultra-high-performance liquid chromatography based triple quadrupole mass spectrometry methodology was developed and validated for simultaneous identification and confirmation of these compounds from CA seeds. Multiple reaction monitoring (MRM) based quantification method was developed with MRM optimizer software for MS1 and MS2 mass analysis. The method was optimized on precursor ions and product ions with the ion ratio of each compound. The calibration curves of seven bioactive analytes showed excellent linearity (r2 ≥ 0.99). The quantitation results found precise (RSD, < 10 %) with good recoveries (84.58 to 101.42%). The matrix effect and extraction recoveries were found within the range (91.66 to 102.11%) for the CA seeds. This is the first MS/MS-based methodology applied to quantifying seven antidiabetic compounds in CA seeds and its extract for quality control purposes.

• 한국동물위생학회지
• /
• 제45권3호
• /
• pp.229-236
• /
• 2022

This study describes an analytical method based on LC-MS/MS for the quantitation of 5 fluoroquinolones (Enrofloxacin, Ciprofloxacin, Marbofloxacin, Norfloxacin and Danofloxacin) in meat, and was applied to 230 meat samples for validation. Quantitation was performed based on a matrix-matched calibration to compensate for the matrix effect on the electrospray ionization. Good linear calibrations (R²≥0.998) were obtained for all fluoroquinolones at 6 concentrations of 1~50 ㎍/kg. Satisfied recoveries of all fluoroquinolones were demonstrated in spiked meat at three levels from 10 to 50 ㎍/kg. The recoveries ranged between 75.8~99.2% in beef, 80.1~99.6% in pork and 72.2~99.8% in chicken, respectively. The limits of quantitation (LOQs) for fluoroquinolones ranged from 0.7 to 3.2 ㎍/kg. We also monitored fluoroquinolones residue in the sample (beef 107, pork 71, chicken 52) using LC-MS/MS. Residues of fluoroquinolones which exceeded maximum residue limits (MRL) were not exceed in any of the 230 samples.

• 방사성폐기물학회지
• /
• 제5권1호
• /
• pp.19-27
• /
• 2007

추출크로마토그래피법과 액체섬광계수법을 이용하여 고체 시료중의 $^{55}Fe$와 $^{63}Ni$ 방사능을 측정할 수 있는 분석법을 확립하고 연구로 2호기의 해체시 발생되는 방사화된 콘크리트 폐기물을 분석하였다. 침전법과 추출크로마토그래피법으로 화학분리를 하면, 경우 Fe의 화학적 회수율은 대부분의 시료에서 90%이상이었으나 Ni의 회수율은 43.6과 46.5%를 나타낸 시료가 있으며 나머지는 62% 이상을 나타내었다. Spiked 시료를 이용하여 분리과정과 액체섬광계수법의 과정을 확인한 결과 $^{55}Fe$의 경우는 3.7% 오차내의, $^{63}Ni$의 경우는 0.7% 오차내의 결과가 얻어졌다. 연구로 2호기의 해체 콘크리트 시료중 $^{55}Fe$ 방사능은 MDA이하의 값도 있으나 TC3시료의 경우는 362Bq/g의 값이 얻어졌다. 그리고 $^{63}Ni$의 경우는 모든 시료에서 MDA이하 값이 얻어져 $^{63}Ni$이 존재하지 않음을 알 수 있었다. 그리고 콘크리트 벽의 해체시 표면의 시료는 $^{55}Fe$의 방사능이 높다가 표면으로부터 깊은 시료일수록 $^{55}Fe$의 방사능이 급격히 줄어들었다.

• 한국환경과학회지
• /
• 제5권5호
• /
• pp.561-567
• /
• 1996

31 종류의 유기 염소계 잔류 농약을 동시에 분석하는 기체 크로마토그래피 방법을 개발하기 위하여 본 연구를 수행하였다. 준비된 분석 시료를 ECD (electron capture detector)로 Ultra-2 column의 GC (gas chromatography)에 주입하였다. Column 충진 물질을 florisil과 alumina N으로 변화시키면서 잔류 용액을 column에 loading하고 용출 용매로는 ether . benzene(2 : 8) solution, hexane . benzene(1 . 1) solution, dichloromethane, acetone 및 methanol을 사용하였다. 분석 결과 column 충진 물질로 florisil을 사용하였을때 (첫째 조건) 6종류의 유기 염소(dichlorfluanid, captan, chlorofenvinfos, folpet, captafol과 dicofol)가 검출되지 않았다. 이 조건에서 dichloromethane과 methanol을 용출 용매로 첨가하였을때는 (둘째 조건) 첫째 분석 조건하에서 검출되지 않았던 6종류의 유기 염소가 검출되었고 thrin계 pesticides, 특히 captan과 captafol의 recovery가 증가하였다(첫째 조건에서와 마찬가지로 충진 물질로 florisil을 사용). 그러나 BHC(benzene hexachloride) 화합물의 recovery는 감 소하였다. 한편 alumina N을 column 충진 물질로 사용하였을 경우에는 dichlorfluanid, chlorofenvinfos, folpet 및 dicofol의 recovery가 증가하였으며 aldrin도 그러하였다. 하지만 captan과 captafol은 그렇지 못하였다. Thrin계 pesticides, captan 및 captafol을 동시에 검출하기 위하여 florisil과 alumina N을 충진 물질로 동시에 사용하고 n-hexane을 충진시켜 용출시킨 결과, captan과 captafol이 검출되지 않았는데 이는 column이 충분히 활성화되지 않았기 때문이라고 생각된다. Column(florisil과 alumina N을 충진 물질로 동시 사용)을 충분히 활성화시키고 여러가지 용출 용매를 사용하여 불순물을 제거하였을때 분석 결과가 가장 우수하였다(31 종류의 유기 염소계 잔류 농약이 sharp하게 검출되었고 높은 감도를 나타내었다).

• 대한수의학회지
• /
• 제42권2호
• /
• pp.171-181
• /
• 2002

Simultaneous multiresidue analysis using liquid chromatography determination for five benzimidazole anthelmintics(thiabendazole, oxibendazole, albendazole, mebendazole and fenbendazole) in bovine muscle, liver and omasum has been described. Blank or benzimidazole-fortified samples(0.5g) were blended with bulk $C_{18}$($40{\mu}m$, 18% load, endcapped, 2g). A column made from the resultant $C_{18}$/animal tissue matrix was first washed with hexane($8m{\ell}$), following which the benzimidazoles were eluted with acetonitrile($8m{\ell}$). Analytes of extracted sample were determined by liquid chromatography with UV detector at 290nm. Correlation coefficients of standard curves for individual benzimidazole isolated from fortified samples, using internal standardization, were linear($0.991{\pm}0.007$ to $0.996{\pm}0.005$) with average relative percentage recoveries from $62.1{\pm}3.8(%)$ to $92.3{\pm}7.5(%)$ for the concentration range($0.2{\sim}6.4{\mu}g/g$), respectively. Recoveries rates of TBZ, MBZ in liver, OBZ, MBZ in muscle and TBZ, MBZ in omasium from fortified benzimidazole were 92.%, 87.3%, 74.5%, 82.7%, 75.2% and 83.5% at condition II, respectively. Condition II showed higher recoveries rates than condition I. These results indicated that the matrix solid phase dispersion(MSPD) methodology is acceptable for the determination of 5 benzimidazole anthelmintics and may also suitable for other matrixes of food animal origin.

• 대한의생명과학회지
• /
• 제9권3호
• /
• pp.145-150
• /
• 2003

In the intestinal mucosa, mast cells are thought to be responsible for the expulsion of parasites. We investigated the relationship of worm expulsion and mast cells in C3H/HeN and BALB/c mice infected with Echinostoma hortense. In addition, we examined whether the worm recovery rate was associated with the strain of mice, and whether a toluidine stain and immunohistochemistry using the c-kit antibody was effective in the detection of mast cells. In order to investigate the mucosal immune response of C3H/HeN and BALB/c mice, each mouse was infected orally with 30 E. hortense metacercariae. Then, the number of mucosal mast cells and worm recovery rates was observed in experimentally infected mouse strains between 1 week and 8 weeks post infection (PI). Mucosal mast cells were increased in 3 weeks P.I. in C3H/HeN and BALB/c mice. On the other hand, only mucosal goblet cells and worm recovery rates correlated in C3H/HeN mice (P=0.0482). Worm recoveries in C3H/HeN mice were 65.7$\pm$5.6, 53.3$\pm$5.4 and 6.7$\pm$0.6 in week 1, 2, and 3 P.I. and strongly decreased in week 3 P.I. Worm recoveries in BALB/c mice were 23.0$\pm$2.5, 10.0$\pm$1.0, and 6.7$\pm$0.6% in week 1, 2, and 3 P.I. and gradually decreased from week 1 P.I. to week 3 P.I. Worm recoveries in C3H/HeN mice were significantly higher than in BALB/c mice (P<0.00l). The number of mast cells in C3H/HeN and BALB/c mice using the anti-c-kit antibody reached to a peak in week 3 P.I. and recovered as normal level in week 5 P.I. and 6 P.I. The number in E. hortense-infected C3H/HeN mice (P=0.0015) was higher than in E. hortense-infected BALB/c mice (P=0.01) compared with the control group. There were significant differences in the number of mast cells among regions of the intestine in in C3H/HeN mice (P<0.05) but not in BALB/c mice (P>0.05). Immunohistochemistry using the anti-c-kit antibody was significant method as an examination of the number of mast cells (P=0.0002). In conclusion, the present study demonstrated that mast cells play an important role in worm recovery, and immunohistochemistry using the anti-c-kit antibody was superior to toluidine stain as an examination of mast cells.

• 한국물환경학회지
• /
• 제22권2호
• /
• pp.321-327
• /
• 2006

This interlaboratory study was designed to evaluate protozoan test methods in water and to predict the major causes of deviation of the methods. Each of four laboratories with previous experience of protozoa analysis in water participated, and met the initial performance criteria of EPA 1623 method provided. The protozoan analysis procedure consists of filtrations, concentration, immunomagnetic separation, dyeing (staining) and counting with observation. We tested three different filtration equipments: capsule filter for 10 L of surface water, and high volume (HV) capsule filter and membrane filter for 100 L of finished water. When the recovery of each step of the procedure was evaluated with EasySeed, the commercial stock of each 100 Cryptosporidium and Giardia, immunomagnetic separation and filtration step were the most crucial steps affecting the stability of the recovery, especially for Cryptosporidium. There was no significant difference of recovery among the filtration methods. Recovery of protozoa from source water were evaluated with spiked EasySeed as matrix tests. The recoveries of Giardia increased significantly in the matrix tests compared those in the deionized water. We also applied red stained mixture stocks of Cryptosporidium and Giardia called ColorSeed as internal standards of water sample tests. The recoveries of both EasySeed and ColorSeed in samples tested were within the range of the criteria, however, the Giardia recoveries using ColorSeed decreased significantly. Further optimization study with ColorSeed will be necessary, considering the convenience of using the internal standard without additional sample analysis. The significant factors of the recovery variation were identified as the differences of laboratories as well as water quality and type of the stock for spiking. The results of this study emphasize the importance of the quality assurance program for protozoan analysis lab in water.

• 한국식품과학회지
• /
• 제30권5호
• /
• pp.1163-1168
• /
• 1998

유기용매에 의한 잔류농약 추출방법을 대체할 신속, 간편, 값싼 방법의 개발을 목표로, 어류조직에 5종의 유기인계 농약 표준용액을 첨가하여, 추출온도와 압력별, 이산화탄소 유속별, 보조용매 종류별, 어류 시료량별, 어류 종류별로 초임계 이산화탄소를 이용하여 첨가회수율을 측정하였다. 조피볼락에 유기인계 농약 표준용액을 첨가한 후 흡수제로 celite를 혼합하여 초임계 이산화탄소로 추출하였을 때 첨가회수율은 추출온도와 추출압력이 낮을수록 증가하였고, 이산화탄소 유속이 높을수록 감소하였다. 보조용매 사용에 따른 회수율의 증가효과는 크지 않았으며, 사용한 보조용매로 methanol, acetone, methylene chloride 중 methylene chloride 10%와 더불어 추출하였을 때 첨가회수율이 가장 높았다. 어류 시료량이 적을수록 첨가회수율이 증가하였다. 조피볼락, 방어, 옥돔, 정어리, 고등어에서의 첨가회수율은 각각 $66.7{\sim}86.3%$, $56.2{\sim}79.2%$, $57.6{\sim}77.8%$, $84.2{\sim}96.3%$, $74.6{\sim}83.6%$로 지방함량이 높은 시료는 지방함량이 낮은 시료보다 첨가회수율이 높았다.