• Analytical Science and Technology
• /
• v.6 no.3
• /
• pp.335-343
• /
• 1993

The structure of cerebrosides from soybean embryo was determined using fast atom bombardment mass spectrometer (FAB-MS), gas chromatography mass spectrometer (GC-MS) and TLC. The components of cerebroside were determined by GC-MS after acid hydrolysis. The molecular weight distribution of cerebroside was measured by positive mode FAB-MS with LiOH saturated 3-nitrobenzylalcohol(3-NBA) matrix. Structures of individual components of complex mixtures can be determined easily by this process. The major constituent of soybean extracted cerebroside was determined as the glucoside of N-2'-hydroxypalmitoyl-sphingadienine.

• Journal of the Korean Vacuum Society
• /
• v.2 no.3
• /
• pp.314-318
• /
• 1993

Quadrupole mass spectrometer는 부분압 측정 및 잔류기체 분석에 널리 이용되고 있는 장비이다. CO, H2, Ar이 혼합되어 존재할 때 quadrupole mass spectrometer의 감도를 10-4∼10-8torr영역에서 측정하고 단일기체로 존재할 때의 감도와 비교하였다. 그 결과 일정한 부분압을 유지하고 있는 경우라도, 주위 분위기 기체 종류와 부위기 기체 압력에 따라 감도 별화가 심한 것을 알 수 있었다. 따라서 QMS를 부분압 측정이나 조성분석에 이용하기 위해서는 이에 대한 특성조사가 반드시 필요하다.

• Journal of the Korean Vacuum Society
• /
• v.16 no.2
• /
• pp.91-98
• /
• 2007

The Korea Research Institute of Standards and Science (KRISS) has developed a residual gas analyzer (RGA) calibration system and measured gas sensitivities for two different types QMSs using nitrogen, argon, and helium. Different gas sensitivities were identified according to mass and pressure, so it was revealed that the gas sensitivity correction is necessary for proper use of mass spectrometers.

• Microbiology and Biotechnology Letters
• /
• v.17 no.3
• /
• pp.241-246
• /
• 1989

Continuous on-line monitoring of cell concentration and growth rate in aerobic batch fermentation process was carried out by analyzing the exhaust gas composition of tormentor with a quadrupole mass spectrometer. From the mass spectrometric analyses of major gaseous components, i.e. $N_2$, $O_2$, $CO_2$ and $H_2O$, and the material balance equations for oxygen and carbon dioxide, oxygen uptake rate (OUR) rind carbon dioxide evolution rate (CER) were instantaneously calculated using a computer (16-bit IBM PC-AT) interfaced to a quadrupole mass spectrometer. The calculated OUR and CER data were used for the estimation of cell concentration and growth rate of Candida utilis during batch culture. It was found that the cell concentration could be satisfactorily estimated from the data of OUR arid CER during the culture and this method could be successfully und for the continuous monitoring of cell growth and growth rate.

• Journal of the Korean institute of surface engineering
• /
• v.48 no.4
• /
• pp.179-184
• /
• 2015

Quadrupole Mass Spectrometers (QMS) is a very useful tool in vacuum process diagnosis. Tungsten filament based ion sources are vulnerable to contamination from process gas monitoring. Common symptoms of quadrupole mass spectrometer malfunction is appearance of unwanted contaminant mass peaks or no detection of any ion peaks. We disassembled used quadrupole mass spectrometer and found out black insulating deposits on inside of ion source parts. Five steps of cleaning procedure were applied and almost full restoration of functions were confirmed in two types of closed ion source quadrupole mass spectrometer. By using a numerical modeling (CFD-ACE+) technique, the electric potential profile of ion source with/without insulating deposit was calculated and showed the possibility of quadrupole mass spectrometer malfunction by the deterioration of designed potential profile inside the ion source.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.9
• /
• pp.1232-1238
• /
• 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
• /
• v.35 no.8
• /
• pp.2403-2409
• /
• 2014

Absolute isotope ratio is a critical constituent in determination of atomic weight. To measure the absolute isotope ratio using a mass spectrometer, mass discrimination factor, $f_{MD}$, is needed to convert measured isotope ratio to real isotope ratio of gas molecules. If the $f_{MD}$ could be predicted, absolute isotope ratio of a chemical species would be measureable in absence of its enriched isotope pure materials or isotope references. This work employed gravimetrically prepared isotope mixtures of argon (Ar) to obtain $f_{MD}$ at m/z of 40 in the magnetic sector type gas mass spectrometer (gas/MS). Besides, we compare the nitrogen isotope ratio of nitrogen trifluoride ($NF_3$) with that of nitrogen molecule ($N_2$) decomposed from the same $NF_3$ thermally in order to identify the difference of $f_{MD}$ values in extensive m/z region from 28 to 71. Our result shows that $f_{MD}$ at m/z 40 was $-0.044%{\pm}0.017%$ (k = 1) from measurement of Ar artificial isotope mixtures. The $f_{MD}$ difference in the range of m/z from 28 to 71 is observed $-0.12%{\pm}0.14%$ from $NF_3$ and $N_2$. From combination of this work and reported $f_{MD}$ values by another team, IRMM, if $f_{MD}$ of $-0.16%{\pm}0.14%$ is applied to isotope ratio measurement from $N_2$ to $SF_6$, we can determine absolute isotope ratio within relative uncertainty of 0.2 %.

• Analytical Science and Technology
• /
• v.26 no.6
• /
• pp.401-406
• /
• 2013

Oxygen($O_2$) consumption and carbon dioxide($CO_2$) excretion of a fertile chicken egg during incubation were measured by a gas mass spectrometer. A closed sample chamber was developed to collect gas samples during the 20 days of artificial incubation of both a fertile and an infertile egg. After leaving an egg in the sample chamber for an hour, using a gas-tight syringe, samples of 2 mL of gas were collected from the closed sample chamber and analyzed using a gas mass spectrometer in 2~4 day intervals. The $O_2$ consumption and $CO_2$ excretion of chicken embryos increased rapidly after 10 days from the starting point of incubation. After 20 days, 23 mL of $O_2$ was consumed and 16 mL of $CO_2$ was excreted per hour. Throughout the whole period of incubation, concentration of $O_2$ decreased 4.3 mol% and $CO_2$ increased only 3.1 mole%, i.e., the mole of consumed $O_2$ and the mole of excreted $CO_2$ were not the same. On the other hand, during the same period, concentration of $N_2$ increased about 1.3 mol% and the increased mole fraction of $N_2$ was comparable with the difference (1.2 mol%) between the mole fraction of consumed $O_2$ and excreted $CO_2$. Therefore, we can attribute the increase of $N_2$ mole% to the difference of mole fraction between consumed $O_2$ and excreted $CO_2$. In this study, through the analysis of gas, we could explain the respiration of a fertile chicken egg during incubation.

• Analytical Science and Technology
• /
• v.12 no.2
• /
• pp.94-98
• /
• 1999

An analysis method of components and isotopic compositions of low pressure gases from nuclear fuel rod using quadrupole mass spectrometer was studied. The calibration curves of each gas in pure and mixtures of He, $N_2$, $O_2$, Ar, Kr and Xe were obtained as a function of pressure and concentration, respectively. Effect of molecular leak, located between sample chamber and analyser chamber, on the sensitivites was also studied. The results suggested that samples could be analysed accurately at the same analytical condition as that of synthetic gas mixture. The difference of sensitivities among isotopes of Kr and Xe was not observed in the range of measured pressure.

• Journal of Korea Foundry Society
• /
• v.41 no.6
• /
• pp.516-520
• /
• 2021

During sand casting, the binders produces gases in cores because high temperature molten metals dissolve the binders into gases and causes gas defects in the casting products. In the present study, quantitative analysis of inorganic binder gas generation was performed using Thermo Gravimetry (TG) and Mass Spectrometer (MS) analyses. The specimen was prepared using organic binders in liquid and solid state, and a mixture of sand and binders. Moisture loss by catalysts was calculated by TG results from liquid and solid binder specimens; it was found that components of gases were different. Quantitative analysis was discussed for generated gases with individual gas component results obtained using TG and MS. It is expected that gas generation can be predicted in the casting simulation using the technique proposed in the present study.