• Food Science and Biotechnology
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• 제15권6호
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• pp.959-966
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• 2006

The electron-capture detector (ECD) of gas chromatographs (GC) has been used widely in pesticide analysis. However, as ECD relies on radioactive material, it is troublesome to purchase and maintain. Therefore, potent replacements for ECD were investigated. A Pulsed-discharge detector (PDD) for ECD was tested and the analytical results of PDD (ECD mode), ${\mu}ECD$, and nitrogen-phosphorus detector (NPD) were compared for 107 pesticides including organochroline, organophosphorus, pyrethroids etc. The number of pesticides identified at the lowest limit of detection (LOD) was 36, 29, and 2 for PDD, ${\mu}ECD$, and NPD, respectively. The remaining pesticides showed same response to PDD and ${\mu}ECD$. The GC-PDD analysis of pesticides spiked into representative agricultural products (brown rice, spinach, and mandarin oranges) also showed good and/or equivalent recoveries using $GC-{\mu}ECD$.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2002년도 하계 학술대회 논문집
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• pp.394-399
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• 2002

국민소득의 증대와 함께 소비자의 고품질 농축산물에 대한 수요와 관심이 날로 증가하고 있다 이에 따라 안전하며 고품질인 농축산물을 소비자에게 공급하기 위하여 안전한 농축산물의 생산, 신선도 유지를 위한 유통구조의 개혁, 품질 및 안전성 평가기술개발을 위한 노력이 보다 더 요구되고 있다. 소비자가 믿고 구매하기 위해서는 농축산물에 대한 품질보증이 필수적이며 이를 위해서는 신속하고 정확한 품질 및 유해물질의 판정기술 개발이 필요하다. 많은 농축산물에 있어서 주요 품질인자인 숙도 및 신선도의 변화는 휘발성 화학물질로 이루어진 냄새의 변화로 나타나므로 이를 측정하여 품질 및 안전성을 간접적으로 판정할 수 있다 기존의 냄새에 의한 품질 판정은 판별전문가에 의한 관능평가법 또는 GC(Gas Chromatography)나 GC/MS(Gas chromatograph mass spectrometer)에 의하여 주로 이루어져 왔다. 하지만, 관능평가법의 경우 판별전문가의 개인적인 차이, 피로, 건강상태 등에 따라 판정의 객관성이 떨어질 우려가 있고, GC나 GC/MS를 이용할 경우 냄새분석에 많은 시간과 노력이 소요되는 문제점이 있다. (중략)

• 약학회지
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• 제32권1호
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• pp.6-13
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• 1988

A gas chromatographic method is described for the determination of volatile free acids(VFAs) in body fluids. VFAs were trace enriched from body fluids by liquid-solid extraction using Chromosorb P as the solid sorbent and ether as the eluant. The enriched VFAs were injected in splitless injection mode onto a HP-20M fused silica capillary column. The flame ionization detector was used as the detector. The present method was applied to the profiling of VFAs in body fluids from patients suffering from the infectious disease, hepatitis. The VFAs concentrations were high in saliva of hepatitis patients and isobutyric acid detected in sera of hepatitis patients compared to healthy subjects.

• 전기학회논문지
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• 제67권9호
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• pp.1232-1238
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• 2018

This paper proposes methods for improving mass spectral resolution for a gas chromatograph mass spectrometer. The slope signs of the 1st and 2nd fitting functions for the ion signal block of each mass index are obtained, and the unnecessary element signals in the ion signal block are removed. The spectrum can be obtained by obtaining the second-order fitting function of the reconstructed ion signal block using only the effective ion signals. In addition, the resolution of the mass spectrum can be improved by correcting the error caused by the shift of the spectral peak position. To verify the performance of the proposed methods, computer simulations were performed using the actual ion signals obtained from the GC-MS system under development. Simulation results show that the proposed method is valid.

• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.524-526
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• 1998

A sensitive and specific method is described for the determination of midazolam in human plasma. The drug was extracted from 1 mL of carbonate buffered plasma (pH 9.6) with 8 mL of diethyl ether. Famprofazone was used as internal standard. The organic phase was evaporated to dryness. The residue was dissolved in methanol for the direct analysis by gas chromatograph-nitrogen phosphorus detector system. In the concentration range of 1-5000 ng/mL, the calibration curve was linear. The coefficients of variation from the precision test were <6% at the range of the concentration of 0.10-2.00 μg/mL and the detection limit for midazolam in 1 mL of plasma was o.5 ng. This assay is more sensitive, selective, simple and rapid than earlier methods. Plasma midazolam concentrations were determined by this method after administration of midazolam.

• Environmental Analysis Health and Toxicology
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• 제16권4호
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• pp.181-188
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• 2001

A gas chromatographic method was established for the simultaneous determination of urinary nicotine and cotinine. The analytes in basified urine containing a sufficient amount of Na$_2$S0$_4$were extracted into dichloromethane by vigorous shaking. Into the transferred organic phase was added a small amount of acidified methanol (0.5 N HCI in methanol), followed by concentrating the mixture to dryness using a mild stream of nitrogen gas. The concentrate was reconstituted with methanol and the final solution analyzed using the gas chromatograph equipped with the nitrogen-phosphorus detector. The reproducibility tests showed coefficients of variation less than 11％ for both compounds. The percent recovery for both analytes ranged from 88 to 103％. The estimated method detection limits for nicotine and cotinine were 0.60 and 5.1 ng/mL, respectively. Extraction efficiencies for both nicotine and cotinine apparently declined without the addition of Na$_2$S0$_4$into the urine. Moreover, the absence of methanolic HCI in the extract resulted in almost complete evaporation of nicotine and partial loss of cotinine during the concentration process, indicating that the formation of nicotine-HCI and cotinine-HCI species is prerequisite to the suppression of the loss of both compounds.

• 대한기계학회논문집B
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• 제23권5호
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• pp.687-694
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• 1999

An experimental study was carried out in two laboratory-scale reactors to investigate the effect of heating rate on the behavior of flame front in a pulverized coal flame. Each. reactors had different heating mechanisms. For reactor A losing large heat through transparent quartz wall. pulverized coal particles were ignited by secondary air of 1050K. Flame front could be visualized through the transparent wall. Reactor B was insulated with castable refractory to minimize the heat loss through the reactor wall and accompanied with secondary air of 573K. Flame front was estimated from the gas temperature and species concentration measured using R-type thermocouple(Pt-Pt/Rh 13%) and gas chromatograph at various coal-air ratios and swirl intensities. The flame front position was closely related with the magnitude of heating rate. The heating rate for lifted flame was of the order of $10^4$ to $10^5K/s$ and for coal Ignition at least over $10^4K/s$. The heating mechanism had little impact on the extinction limits. The weak swirl number of 0.68 forced the flame front to move toward the upstream by the rapid mixing of coal and air. The primary/secondary momentum ratio was an inappropriate variable to distinct the liftoff of flame.

• Elastomers and Composites
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• 제22권1호
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• pp.11-19
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• 1987

A coil pyrolyzer and processor-controlled gas chromatograph were used for analysis of rubber for compounding ratio of the single and blend rubber vlucanizates. Variables such as sample size, pyrolysis temperature, time allowed for pyrolysis, the column packing material, its length and programmable temperature for gas chromatography were examined to obtain optimum condition for application to NR, BR and SBR blends. By application fixed conditions, three kinds of standard curves were finally obtained from thirty samples of blend vulcanizates which were prepared in the pilot plant, NIRI. It is possible to determine rubber composition and their ratio in NR, BR and SBR products by pyrolysis.

• 한국토양환경학회지
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• 제3권1호
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• pp.3-9
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• 1998

본 연구는 휘발성 유기 화합물로 오염된 가솔린 지역에서 soil-gas의 분석결과로부터 오염도를 유추하는 기법에 대하여 서술 하였다. Soil-gas의 채취방법으로는 펌프를 이용한 1)grab sampling법과 흡착제 trap을 사용한 2)passive sampling법이 있다. Grab sampling법은 특정시간에 특정장소에서의 오염도를 보여주며, 반면에 passive sampling법은 특정위치에서 시간에 따른 오염도의 변화를 보여 준다. Soil-gas의 분석은 1)PID나 FID와 같은 작은 검지기에 의해서 총괄 탄화수소량을 측정할수도 있고 2)기체농도에 따라서 색깔이 변하는 지시약이 채워진 기체검지기 튜브를 사용할수도 있으며 3)여러가지 화합물을 한 번에 분석할수 있는 이동형 GC를 사용할수도 있다. Soil-gas를 이용한 측정법은 매우 값싸며 세밀한 정밀조사를 하기 위한 전단계에서 사용할 수 있는 유용한 방법으로 추천할만하다 하겠다.

• 한국추진공학회지
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• 제15권1호
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• pp.1-10
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• 2011

가스연소와 촉매연소 실험을 통해 열교환 연소기의 연소 및 소염한계에 대하여 레이놀즈 수에 적용하여 성능평가를 수행하였으며, 마이크로 스케일 연소 장치에 대한 적용 가능성에 대해 살펴보았다. 본 논문에서는 연소기의 특성을 살펴보기 위해 나선형 연소기의 물리적 크기와 회전수를 변화시킨 스위스롤 연소기를 제작하여 실험을 수행하였다. 또한 연소가스 분석을 통한 연소효율에 대해서도 살펴보았다. 실험 결과를 바탕으로 스위스롤 연소기의 최적 작동상태에 대해서도 분석하였다.