• Nuclear Medicine and Molecular Imaging
• /
• v.41 no.6
• /
• pp.566-569
• /
• 2007

Purpose: Analysis of volatile organic solvents in 2-deoxy-2-$[^{18}F]$ fluoro-D-glucose ($[^{18}F]$FDG) preparations was performed by gas chromatography (GC), in accordance with USP. Materials and Methods: Analyses were carried out on a Hewlett-Packard 6890 gas chromatography equipped with an FID. Results: We determined the amounts of ethanol and acetonitrile on every batch of our routine $[^{18}F]$FDG preparations, ranging between 5000 ppm and 100 ppm. In our routine preparation of $[^{18}F]$FDG, the amount of acetonitrile and ethanol in the final product were well below the maximum allowable limit described in the USP. Conclusion: Our $[^{18}F]$FDG preparations were in accordance with the suggested USP maximum allowable levels of the quality control analysis of volatile organic compounds.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.51-52
• /
• 2000

생물공정의 운전에 있어서 적절한 공정변수가 부족한 경우가 많다. 이것은 멸균과정을 견딜 수 있는 신뢰성 높은 센서가 부족하기 때문이다[1]. 생물공정에 주로 사용되는 센서로서는 온도, pH, D.O., rpm, viscosoty 등이 있으나 이 센서들은 배양액의 물리적 혹은 화학적 상태를 측정할 수 있는 경우가 대부분이다[2]. 미생물의 대사활동과 관련이 있는 공정 변수로는 배출가스의 성분을 측정하여 얻을 수 있는 Oxygen uptake rate, Carbon dioxide evolution rate 및 Respiratory quotient가 있으며 현재 생물공정의 운전에 사용되고 있다[3]. 그러나 반복적인 센서의 보정과 연결관의 잦은 청소 및 보수를 필요로 하여 제한적으로 사용되고있는 실정이다. 자동화된 습식분석장치, Gas chromatograph, High Performace Liquid Chromatograph 혹은 Mass spectrophtometry 등을 온라인 샘플 처리장치와 연결하여 발효조의 배양액의 성분을 온라인으로 분석하고 공정의 운전에 응용하는 사례가 많이 발표되었다[4-6]. 고가의 장비 및 운전의 번거러움이나 추가적인 인력이 필요하므로 역시 특별한 경우에만 사용되고 있다. 이외에도 여러 종류의 온라인 센서 및 바이오 센서등이 개발되어 사용되고 있으나 역시 그 사용범위는 특수한 영역에 한정되어있다. 이와 같이 새로운 센서를 개발하여 공정변수를 측정하려는 시도중의 하나가 소프트웨어 센서의 개발이다. 이 것은 공정상에서 발생하는 1차 공정변수를 이용하여 배양액의 상태 혹은 2차적인 공정 변수를 추측해내는 것이다. 대부분의 경우 기존의 공정 변수를 사용하므로 추가적인 비용이 들지 않고 소프트웨어의 형태로 구현되므로 센서의 보정과 설치 및 유지관리의 노력이 매우 적은 장점이 있다. 본 연구에서는 생물공정에서 자동제어 과정에서 발생하는 여러 가지 공정상의 제어 신호로부터 새로운 공정 변수를 얻어내고자 시도하였다. 대부분의 생물공정에서는 pH의 자동제어가 필수적인데 자동제어 과정에서 발생하는 pH 제어 신호 및 pH의 변화 응답신호를 이용하여 배지의 완충용량의 변화와 알칼리의 소비속도를 온라인으로 측정할 수 있었다. 여기에 인공지능망을 설계하여 균체의 량을 온라인으로 추정하는 방법을 개발하였다 [7].산업용 발효조의 운전 온도는 주로 냉각수의 단속적인 공급에 의하여 항상 일정하게 조절된다. 따라서 냉각수의 냉각량을 측정하면 미생물의 배양시 발생하는 대사열량을 측정할 수 있게 된다. 본 연구에서는 실험실의 발효조를 냉각수의 단속적인 공급에 의하여 자동온도 조절이 되도록 개조하고 여기에 냉각수의 유출입 지점에 온도센서를 부착하여 냉각수의 온도를 측정하고 냉각수의 공급량과 대기의 온도 등을 측정하여 대사열의 발생을 추정할 수 있었다. 동시에 이를 이용하여 유가배양시 기질을 공급하는 공정변수로 사용하였다 [8]. 생물학적인 폐수처리장치인 활성 슬러지법에서 미생물의 활성을 측정하는 방법은 아직 그다지 개발되어있지 않다. 본 연구에서는 슬러지의 주 구성원이 미생물인 점에 착안하여 침전시 슬러지층과 상등액의 온도차를 측정하여 대사열량의 발생량을 측정하고 슬러지의 활성을 측정할 수 있는 방법을 개발하였다.

• Applied Biological Chemistry
• /
• v.26 no.2
• /
• pp.104-109
• /
• 1983

Gas chromatographic method for the analysis of phorate(0,0-diethyl S-ethyl-thiomethyl phosphorithioate) and its metabolites in soil and vegetables was studied by using a mixed phase column(10% DC-200+8% Reoplex-400+2% QF-1 on Gas Chrom Q, $1.8{\times}2mm$ i.d, borosilicate glass column). This column can separate completely phorate and its four metabolites except phoratoxon sulfoxide. Retention time of standard mixture ranged 1.8 to 16.1 minutes at column temperature programming from 130 to $200^{\circ}C$ at $5^{\circ}C/min$ and detector sensitivity was also very high(0.05 to 1.05ng). Recoveries from soil and vegetables untreated but fortified with phorate and its three major metabolites at 0.05 and 0.5ppm levels were above 90% for phorate, phorate sulfoxide and phorate sulfone while recovery of phoratoxon metabolite was about 84%.

• Analytical Science and Technology
• /
• v.35 no.3
• /
• pp.116-123
• /
• 2022

Polymer bags, metallic canisters, and glass bottles have been used as containers for analyzing the volatile organic compounds (VOCs) in air. In this study, various sampling containers were compared to investigate the short-term stability of VOCs, that is, from the time they are sampled to the time they are analyzed. Polyvinyl fluoride (PVF), polypropylene (PP), polyester aluminum (PE-Al) bags, canisters, and glass bottles were used as sample containers. A 100 nmol/mol standard gas mixture of benzene, toluene, ethylbenzene, m-xylene, styrene, and o-xylene was used for the VOC comparison. Changes in the concentrations of samples stored for 10~20 day in each container were measured using a thermal desorption-gas chromatograph-flame ionization detector (TD-GC-FID). As a result, VOCs stored in a canister and two kinds of amber glass bottles have shown immaterial decreases in concentration in one week, and more than 80 % of the initial concentration was maintained for two weeks. In the case of polymer bags, the concentration of all VOCs, except benzene and toluene, were remarkably decreased below 70% of the initial concentration in one day. Particularly, ethylbenzene, xylene, and styrene have shown dramatic decreases in concentration below 30 % of the initial concentration in all polymer bags in one day.

• Economic and Environmental Geology
• /
• v.40 no.1 s.182
• /
• pp.129-140
• /
• 2007

CFC(CFC-12, CFC-11 and CFC-113) analytical system for air and water was constructed using a customized purge and trap extraction device and a gas chromatograph with an electron capture detector. Sampling methods of air and water for CFCs were also established. The analytical system was experimentally optimized to result in reproducibilities of triplicates less than 2% for current air samples and less than 5% for groundwater samples with CFC-12 concentration of 160 to 180 pg/kg, and verified with respect to the CFC system in USGS, which showed analytical results were in agreement within 10%. CFCs in air were monitored at three sites over 19-month period in the central part of South Korea, and the result indicates no significant local sources of CFCs in those areas. For groundwater in Jeju Island, CFCs were measured over a year with a two-month interval. The time-series data showed seasonal fluctuations which could be interpreted by the effect of recharge pulse derived from large amount of rainfall during monsoon period with a few month delay, which indicates high permeability of basaltic rocks in Jeju Island.

• Applied Chemistry for Engineering
• /
• v.18 no.3
• /
• pp.245-250
• /
• 2007

Adsorption characteristics of 1,2-dichlorobenzene on the surface of heat treated silica gel were determined by the moment analysis. The heat treatment of the silica gel was performed at temperatures of 150, 500, and $800^{\circ}C$ and pulse-response of 1,2-dichlorobenzene was measured in a gas chromatograph equipped with thermal conductivity detector (TCD) using the packed column. Equilibrium adsorption constants and isosteric heat of adsorption were recorded the highest value at $500^{\circ}C$. This might be due to the increase of interaction between silica surface and 1,2-dichlorobenzene as the decrease of OH concentration and moisture by increase of heating temperature. Axial dispersion coefficient calculated by the moment method was about $0.046{\times}10^{-4}{\sim}1.033{\times}10^{-4}m^2/sec$ and pore diffusivity of heat treated silica gel at $500^{\circ}C$ measured the lowest value. Because heat treating at $800^{\circ}C$ caused the specific surface area to reduce, equilibrium adsorption constants and isosteric heat of adsorption were decreased.

• Applied Chemistry for Engineering
• /
• v.17 no.2
• /
• pp.229-234
• /
• 2006

The effect of ZnO in the decomposition of poly(vinyl chloride) (PVC) and polystyrene (PS) mixtures in air atmosphere has been studied by thermogravimetry (TG) and gas chromatograph-mass spectrometry (GC-MS) under various mixing ratios and reaction temperatures. From this work, it can be seen that the yields of a liquid product were increased with the increase of PS in mixtures, whereas those of gaseous products were decreased. And the yields of a gaseous product and HCl were decreased with the increase of ZnO in mixtures. It was also found that HCl was rarely produced at ZnO/Mixture = 0.5 by the effect of ZnO in dehydrochlorination of PVC.

• Journal of Environmental Science International
• /
• v.22 no.11
• /
• pp.1451-1456
• /
• 2013

This study was conducted to investigate the timely characteristics of phytoncide in forest trail of Ulsan Metropolitan. Air samples were collected from July to October 2011. The phytoncide were detected and quantified using a Gas Chromatograph Mass Spectrometer(GC/MSD). This study are summarized as follows ; The highest levels of phytoncide concentration of August is higher than other months in Munsu Mt. and Samho Mt.(town mountains). The higher phytoncide emission rates found in the morning and in the evening. The concentration of phytoncide was understanded to be greatly influenced by environment change of day time.

• Journal of Environmental Science International
• /
• v.22 no.11
• /
• pp.1415-1419
• /
• 2013

This study was conducted to investigate the seasonal variation characteristics of phytoncide in trail of Ulsan Metropolitan. Air samples were collected from May to December 2011. They were collected using Tenax Ta tube and phytoncides were detected and quantified using a Gas Chromatograph Mass Spectrometer (GC/MSD). This study are summarized as follows; The seasonal concentrations of phytoncide are Munsu Mt. 272.3 ${\mu}g/m^3$, Samho Mt. 192.4 ${\mu}g/m^3$, Shinbul Mt. 50.9 ${\mu}g/m^3$, Sibli Bamboo forest 22.4 ${\mu}g/m^3$ and Joongbu Fire Station 24.4 ${\mu}g/m^3$. In Munsu Mt., Samho Mt. and Shinbul Mt. major component ratio is ${\alpha}$-Pinene > ${\beta}$-Pinene+Myrcene >Limonene >Camphene > ${\gamma}$-Terpinene > ${\alpha}$-Terpinene. Bamboo forest and Joongbu fire station major component ratio is ${\alpha}$-Pinene >Limonene > ${\beta}$-Pinene+Myrcene >Camphene > ${\alpha}$-Terpinene. The variation of seasonal concentration is summer >spring >fall >winter. The phytoncide concentration of coniferous forest(Munsu Mt., Samho Mt.) is higher than broadleaf forest(Shinbul Mt.).

• Journal of Soil and Groundwater Environment
• /
• v.15 no.1
• /
• pp.9-18
• /
• 2010

In this study, Solid-phase micro-extraction (SPME) with Gas Chromatograph using Flame Ionization Detector (GC/FID) was studied as a possible alternative to liquid-liquid extraction for the analysis of Methyl tert-butyl ether (MTBE) and Tertiary-butyl ether (TBA) in water and an optimization condition of trace analysis of MTBE and TBA using the design of experiment (DOE) was described. The aim of our research was to apply experimental design methodology in the optimization condition of trace analysis of fuel oxygenated compounds in soil-phase microextraction with GC/FID. The reactions of SPME were mathematically described as a function of parameters of Temp ($X_1$), Volume ($X_2$), Time ($X_3$) and Salt ($X_4$) being modeled by the use of the partial factorial designs, which was used for fitting 2nd order response surface models and was alternative to central composite designs. The model predicted agreed with the experimentally observed result ($Y_1$(MTBE, $R^2$ = 0.96, $Y_2$ (TBA, $R^2$ = 0.98)). The estimated ridge of the expected maximum responses and optimal conditions for MTBE and TBA were 278.13 and (Temp ($X_1$) = $48.40^{\circ}C$, Volume ($X_2$) = 73.04 mL, Time ($X_3$) = 11.51 min and Salt ($X_4$) = 12,50 mg/L), and 127.89 and (Temp ($X_1$) = $52.12^{\circ}C$, Volume ($X_2$) = 88.88mL, Time ($X_3$) = 65.40 min and Salt ($X_4$) = 12,50 mg/L), respectively.