• 한국대기환경학회지
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• 제30권1호
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• pp.59-67
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• 2014

In 1995 Kimchi refrigerator was developed at first, and has used HFC-134a as refrigerant. Kimchi refrigerator has been made 1,044,694 on the basis of 2010, disposed about 160,000 per year. Although mobile air conditioning, commercial refrigerator, general refrigerator is regarded as a major source of HFC-134a, little information is available for its emission characteristics of HFC-134a. This paper addresses the fugitive emission factors of Kimchi refrigerator at use-phase and disposal-phase. The residual quantities of Korean-made fifty three waste Kimchi refrigerators were weighed using a commercial recover of refrigerants to determine the emission factors at the disposal-phase. On the other hand, the emission factors at use-phase were estimated from the residual quantities and operating times. The average residual rate of forty three scarp Kimchi refrigerators is determined to be $74.6{\pm}5.2%$. The emission factor at the use-phase is estimated to be $3.5{\pm}0.8%/yr$ as a result of using average age of 11.7 years and the average residual rate determined here. The emission factor at the disposal-phase is determined to be 31.3% after adopting 58% of the recycling rate of refrigerant reported by Recycling Center. We estimate 3.1 g/yr for the average emission quantity of HFC-134a per operating refrigerator, while 22.5 g for that per waste Kimchi refrigerator. Since the chemical compositions of refrigerant of waste Kimchi refrigerator were the same as those of new refrigerant, it is expected that the HFC-134a recovered from waste Kimchi refrigerator can be reused for refrigerant.

• KSBB Journal
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• 제31권3호
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• pp.186-191
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• 2016

A liquid chromatographic method for the enantiomer separation of fluoxetine was performed using covalently bonded and coated type polysaccharide-derived chiral stationary phases (CSPs). The degree of enantioseparation is affected by the used CSPs and mobile phases. The performance of Chiralpak IC was superior to the other CSPs used in this study. Out of various solvent composition and additives, the greatest separation and resolution was observed using Chiralpak IC with mobile phase of 2-propanol in hexane with diethylamine as an additive. Semi-preparative separation of fluoxetine was performed on the analytical Chiralpak IC column to obtain (R)- and (S)-fluoxetine enantiomer with high chemical and optical purity. From the overall study, the developed liquid chromatographic method on polysaccharide-derived CSPs is expected to be very useful for the enantiomer separation of fluoxetine.

• KSBB Journal
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• 제15권5호
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• pp.452-457
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• 2000

Buffer의 특성에 맞는 체류인자에 관한 모텔식을 얻기 위 해서는 buffer 9} 양이온의 농도에 관한 관련식을 실험으로 결 정해야 한다 또한 model 식에서 비이온과 음이온의 체류인 자를 나타내는 ko와 k의 값이 일정한 경향을 나타내고 있기 때문에 buffer의 농도와 modifier의 농도를 동시에 고려한 model 식이 가능하게 된다. 본 연구에서 제안한 모델식을 이용하여 임의의 buffer의 농도에 따른 시료의 체류시간을 예측할 수 있다. 이러한 모텔식을 이용하여 buffer를 이 용한 RP-HPLC의 분석 및 분리조건을 예측할 수 있고 시행 오차적인 방법보다 빠른 시간 내에 최적의 분석 및 분리조건 을 얻을 수 있다

• Environmental Engineering Research
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• 제23권3호
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• pp.309-315
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• 2018

Chlortetracycline (CTC) is one of the most important compounds in antibiotic production, and its distribution has been widely investigated due to health and ecological concerns. This study presents systematic approach to optimize the high-performance liquid chromatography-tandem mass spectrometry for analyzing CTC in a multiple reaction monitoring mode ($479{\rightarrow}462m/z$). One-factor-at-a-time (OFAT) test with response surface analysis (RSA) was used as optimization strategy. In OFAT tests, the fragmentor voltage, collision energy, and ratio of acetonitrile in the mobile phase were selected as major factors for RSA. The experimental conditions were determined using a composite in cube design (CCD) to maximize the peak area. As a result, the partial cubic model precisely predicted the peak area response with high statistical significance. In the model, the (solvent composition) and (collision $energy^2$) terms were statistically significant at the 0.1 ${\alpha}$-level, while the two-way interactions of the independent variables were negligible. By analyzing the model equation, the optimum conditions were derived as 114.9 V, 15.7 eV, and 70.9% for the fragmentor voltage, collision energy, and solvent composition, respectively. The RSA, coupled with the CCD, offered a comprehensive understanding of the peak area that responds to changes in experimental conditions.

• Mass Spectrometry Letters
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• 제8권2호
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• pp.29-33
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• 2017

Understanding the mechanisms that control and concentrate the observed electrospray ionisation (ESI) response from peptides is important. Controlling these mechanisms can improve signal-to-noise ratio in the mass spectrum, and enhances the generation of intact ions, and thus, improves the detection of peptides when analysing mixtures. The effects of different mixtures of aqueous: organic solvents (25, 50, 75%; v/v): formic acid solution (at pH 3.26) compositions on the ESI response and charge-state distribution (CSD) during mass spectrometry (MS) were determined in a group of biologically active peptides (molecular wt range 1.3 - 3.3 kDa). The ESI response is dependent on type of organic solvent in the mobile phase mixture and therefore, solvent choice affects optimal ion intensities. As expected, intact peptide ions gave a more intense ESI signal in polar protic solvent mixtures than in the low polarity solvent. However, for four out of the five analysed peptides, neither the ESI response nor the CSD were affected by the volatility of the solvent mixture. Therefore, in solvent mixtures, as the composition changes during the evaporation processes, the $pK_b$ of the amino acid composition is a better predictor of multiple charging of the peptides.

• 대한화학회지
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• 제30권4호
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• pp.352-358
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• 1986

페놀류의 머무름 거동에 대한 실험적 관찰을 이성분용매인 MeOH-Water, ACN-Water, THF-Water와 삼성분용매인 MeOH-Water, ACN-Water, THF-Water계에서 수행했다. 이 머무름 거동의 데이타들로써 용매의 성분비에 따른 크기인자를 예측할 수 있는 선형방정식을 얻었다. 또 페놀류의 최적 분리에 적합한 MeOH-Water이성분 용매를 기준하여 이론적으로 용매세기가 같은 이성분과 삼성분용매를 사용했고 이 등용매세기하에서 시료에 대한 머무름 거동의 특이성 효과는 이성분용매계가 삼성분용매계보다 더 크게 나타났다.

• 대한화학회지
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• 제37권6호
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• pp.604-611
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• 1993

초임계 유체 크로마토그래피(Supercritical Fluid Chromatography, SFC)는 종래의 크로마토그래피 방법으로 분석하기 어려운 물질을 분석해 내는 기술로써 발전이 되어왔다. 그러나, SFC에서 이동상으로 많이 사용되고 있는 초임계 C$O_2$는 용매로써 특성이 n-hexane과 매우 비슷하여 극성이 큰 시료들을 용출(elution)시키기가 어렵다. 이러한 점을 해결하기 위하여 초임계 C$O_2$에 극성을 지닌 물질 즉, 변형제(modifier)를 섞어서 이동상으로 사용할 수 있다. 본 연구에서는 초임계 C$O_2$에 변형제를 첨가시키는 새로운 방법을 개발하였고, 변형제로써 초임계 C$O_2$에 첨가된 수분(H$_2O$)의 양을 perfluorosulfonate ionomer(PFSI) film을 이용해 만든 amperometric microsensor로써 측정하였다. 이와같은 방법을 사용함으로써 포화 column보다 상당히 긴 시간동안 일정하게 수분을 첨가할 수 있었고, 실제로 이 방법을 사용하여 순수한 C$O_2$ 이동상만으로는 분리하기 어려운 몇 가지 살균제와 살충제에 적용한결과 좋은 크로마토그램을 얻었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권6호
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• pp.495-499
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• 2004

The analyses of peak shapes in chromatography are useful in operating chroma­tographic system. The asymmetry and sharpness of a chromatographic peak are estimated by the reversed-phase adsorption of two standard peptides (angiotensin II bradykinin) on $C_{18}$ In this work, the average particle diameters of $C_{18}$ were 5 and 15 $\mu$m, while the pore sizes were 100 and 300 A. The composition of the mobile phase was $50/50\;vol.\;{\%}$ of a binary mixture of acetonitrile and water with $0.1\%$ TFA, and the particles were packed in a stainless column ($4.6{\times}150$ mm). The third and the fourth central movement were calculated from the chromatographic elution curves by moment analysis. The peak asymmetry was determined by two theoretical calculations: the asymmetry factor by elution peak analysis and skewness with moment analysis. The sharpness was estimated by the fourth central moment. In this work, the most acceptable skewness was calculated when the pore size was 300 A. The large excess was observed on small pore size.

• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.65-70
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• 2002

We have evaluated the specific hydroxyl group-solvent and carbonyl group-solvent interactions by using an Alltima C18 stationary phase and by measuring the retention data of carefully selected solutes in 60/40, 70/30, and 80/20(v/v%) acetonitrile/water eluents at 25, 30, 35, 40, 45, and 50 oC. The selected solutes are phenol, acetophenone, alkylbenznes(benzene to hexylbenznene), 4 positional isomers of phenylbutanol, 5-phenyl-1-pentanol, 3 positional isomers of alkylarylketone derived from butylbenzene, and 1-phenyl-2-hexanone. The magnitudes of hydroxyl group-acetonitrile/water specific interaction enthalpies are larger than those of carbonyl group-acetonitrile/water specific interaction enthalpies in general while the magnitudes of carbonyl group-methanol/water specific interaction enthalpies are larger than those of hydroxyl group-methanol/water specific interactions. We observed clear discrepancies in functional group-solvent specific interaction among positional isomers. The variation trends of solute transfer enthalpies and entropies with mobile phase composition in the acetonitrile/water system are much different from those in the methanol/water system. The well-known pocket formation of acetonitrile in aqueous acetonitrile mixtures has proven to be useful to explain such phenomena.

• Korean Chemical Engineering Research
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• 제47권2호
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• pp.258-261
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• 2009

본 연구에서는 추출용매 물 100%을 이용하여 다양한 초음파 에너지(35, 72, 170 KHz)와 추출 시간(30, 60 min)에 의한 고삼으로부터 식물성에스트로겐 제니스테인 및 포르모노네틴의 추출량과 일반성분의 영향을 비교하였다. 전처리 단계는 초음파추출, 여과, 농축, 막분리로 구성되었다. 추출된 용액은 역상 고성능 액체크로마토그래피 (HPLC)를 사용하여 분석하였다. 이동상 조성은 A는 물/아세트산(99.9/0.1 vol%), B는 아세토니트릴/아세트산(99.9/0.1 vol%)이며, A/B를 80/20~65/35 vol%로 60분 동안 선형적으로 변화시켰다. 실험결과에 의하면 일반성분은 탄수화물(0.255~0.413%)을 제외한 나머지 성분들의 함량은 거의 비슷하게 확인되었다. 또한 주파수 170 KHz, 60 min에서 추출량이 3.17 g으로 추출 수율이 가장 우수하였고 천연물관련 화학 및 생물학 연구에 기초자료로 도움이 될 것이다.