• Mass Spectrometry Letters
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• 제1권1호
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• pp.29-32
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• 2010

Cross reacting antibodies can cause an overestimation of the results of immunoassays. Therefore, alternative methods are needed for the accurate quantification of steroids. Gas chromatography combined with isotope-dilution mass spectrometry (GC-IDMS) is developed to quantify urinary active androgens, testosterone, epitestosterone and dihydrotestosterone, which are clinically relevant androgens to both hair-loss and prostate diseases. The method devised involves enzymatic hydrolysis with $\beta$-glucuronidase, solid-phase extraction, liquid-liquid extraction using methyl tert-butyl ether and subsequent conversion to pentafluorophenyldimethylsilyl-trimethylsilyl (flophemesyl-TMS) derivatives for sensitive and selective analysis in selected-ion monitoring mode. Flophemesyl-TMS derivatization not only eliminates matrix interference but also has a good peak resolution within a 6 min-run. A selective and sensitive GC technique with flophemesyl-TMS derivatives also allows accurate quantitative analysis of three active androgens when combined with IDMS. The limit of quantification of the three analytes was <50 pg/mL, and extraction recoveries ranged from 91.9 to 102.1%. The precision and accuracy were 1.2~6.5% and 89.0~106.7%, respectively. This GC-IDMS method can be useful for evaluating the drug efficacy and monitoring the biological processes responsible for male-pattern baldness and prostate diseases.

• Bulletin of the Korean Chemical Society
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• 제25권10호
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• pp.1465-1470
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• 2004

A short and efficient synthesis, solvent extraction and potentiometric measurements of new thiazole-containing naphtho-crown ethers are reported. The naphthalene moiety enhances the ammonium ion selectivity over potassium ion. The selectivity of ${NH_4}^+/K^+$ follows the trend $3\;{\approx}\;2\;>\;1$, indicating that the differences in conformational changes of 2 and 3 in forming ammonium complexes affect little on the resulting ammonium/potassium extraction selectivity ratio. The ammonium ion-selective electrodes were prepared with noctylphenyl ether plasticized poly(vinyl chloride) membranes containing 1-4 the effect of one naphthalene unit introduced on either right (2) or left (3) side of thiazolo-crown ether on their potentiometric properties (e.g., ammonium ion selectivity over other cations, response slopes, and detection limits) were not apparent. However, the ammonium ion selectivity of 1, 2 and 3 over other alkali metal and alkaline earth metal cations is 10-100 times higher than that of nonactin.

• 한국산학기술학회논문지
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• 제9권3호
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• pp.794-799
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• 2008

초음파처리가 십자화과 채소의 sulforaphane 함량 분석에 미치는 영향을 GC/MS를 이용하여 검토하였다. 무, 알타리무, 순무, 양배추, 브로콜리를 각각 dichloromethane을 추출용매로 하여 초음파처리 후 용매 추출 및 질소 농축을 하고, m/z 72, 160, 55, 114을 선택이온측정법(selective ion monitoring, SIM)을 이용하여 분석하였다. 각 채소류의 sulforaphane 함량은 브로콜리가 149.0 ppm으로 가장 많았으며, 양배추(67.9 ppm), 무(35.4 ppm)의 순으로 높았다. Sulforaphane 추출율은 진탕교반(shaking)만 할 경우보다 초음파처리(sonication)후 진탕교반(shaking)을 할 경우 2.7배 높은 것으로 나타났다. 따라서 초음파추출공정이 sulforaphane의 추출효율 향상에 유효한 방법으로 판단된다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.588-589
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• 2018

• Bulletin of the Korean Chemical Society
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• 제18권12호
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• pp.1256-1260
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• 1997

A series of acyclic polyethers bearing amide end-groups and lipophilic alkyl chains (3-5) were successfully synthesized with quantitative yields. Based upon the transport experiment in a bulk liquid membrane (BLM) system and solvent extraction, a very high selectivity of Pb2+ over other transition metal cations was observed. Measurement of thermodynamic parameters for complexation in methanol at 25 ℃ gave a strong evidence for excellent selective complexation for lead ion over other transition metal ions.

• 대한화학회지
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• 제43권4호
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• pp.418-422
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• 1999

Cr(III)과 Cr(VI)이온 각각을 Aliquat 336으로 단계적으로 용매추출하여 분리하고 원자흡수분광법으로 정량하였다. 즉, $Cr^{3+}$와 $Cr_2O_7^{2-}$의 혼합용액으로부터 Aliquat 336/MIBK로 먼저 $Cr_2O_7^{2-}$을 선택적으로 추출하고, 그 추출액 중의 농도를 $N_2O-C_2H_2$ 불꽃으로 측정한 다음, 남은 수용액에 citrate를 가하여 $Cr^{3+}$을 음의 착이온으로 만들어 같은 추출제를 사용하여 같은 방법으로 추출 및 정량하였다. $Cr^{3+}$와 $Cr_2O_7^{2-}$의 농도가 Cr로서 각각 0.1∼1.0 g/mL 범위의 혼합시료 50mL부터 1%(V/V) Aliquat 336/MIBK 5 mL로 1회씩 추출하여 각 농도에 대한 분석결과, 회수율이 98.8∼101.7%였다.

• 한국분말재료학회지
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• 제30권1호
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• pp.22-28
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• 2023

The global demand for raw lithium materials is rapidly increasing, accompanied by the demand for lithiumion batteries for next-generation mobility. The batch-type method, which selectively separates and concentrates lithium from seawater rich in reserves, could be an alternative to mining, which is limited owing to low extraction rates. Therefore, research on selectively separating and concentrating lithium using an electrodialysis technique, which is reported to have a recovery rate 100 times faster than the conventional methods, is actively being conducted. In this study, a lithium ion selective membrane is prepared using lithium lanthanum titanate, an oxide-based solid electrolyte material, to extract lithium from seawater, and a large-area membrane manufacturing process is conducted to extract a large amount of lithium per unit time. Through the developed manufacturing process, a large-area membrane with a diameter of approximately 20 mm and relative density of 96% or more is manufactured. The lithium extraction behavior from seawater is predicted by measuring the ionic conductivity of the membrane through electrochemical analysis.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권6호
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• pp.454-458
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• 2004

A study of the POSE (predispersed solvent extraction) for succinic acid by colloidalliq­uid aphrons was conducted. The organic phase contaning TOA (tri-n-octylamine) and 1-octanol permits a selective extraction of succinic acid from its aqueous solution. There was no difference of the extractability of POSE and that of conventional mixer-settler type extraction. Taking into account the no mechanical mixing in POSE, it was concluded that the POSE process is more adaptive than the conventional mixer-settler type extraction process. From mass transfer analysis at the various concentration of TOA in counter-current continuous operation, the concentration of TOA had no influence on the mass transfer coefficient. The loading values in continuous POSE were almost same as those in batch operation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권6호
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• pp.386-394
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• 2001

Carboxylic acids are examples of compounds with wide industrial applications and high potential, This article presents the principles of reactive extraction along with the character-istics of tertiary amine extractants, while is given on considering the effect of the amine class and chain length, As such a brief overview the current research on reactive extraction, including the recovery of citric acid, selective amine-based extraction , and extractive fermentation is given. When discussing extractive fermentation strategies for reducing solvent toxicity are also suggested based on specific examples. Finally, solvent regeneration and stripping of extracted acid explained.

• 대한금속재료학회지
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• 제46권12호
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• pp.823-829
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• 2008

The solvent extraction process for the recovery of vanadium from leaching solution of SCR(selective catalytic reduction) spent catalyst was investigated by using Alamine336 as an extractant. The effects of experimental conditions, such as initial pH and concentration of sulfate ion, and ammonia concentration of stripping solution were studied. The extraction percentage of vanadium were increased with the increase of initial pH of leaching solution and decreased with the increase of sulfate ion. More than 99% of vanadium in leaching solution were extracted and stripped at the A/O ratio of 1.0 in 2 stages. On the basis of these results, an optimum solvent extraction process which vanadium was effectively recovered from SCR spent catalyst was proposed.