• Title/Summary/Keyword: mass spectrum

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An extension of new laser pulse atom-probe construction and time-of-flight mass spectrum of $H_2$ and He gas (A new laser pulse atom-probe 제작 및 $H_2$ 가스와 He 가스의 time-of-flight mass spectrum)

  • 송순달;홍남관
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.7 no.3
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    • pp.465-472
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    • 1997
  • An extension of new test methods for surfaces with an apparatus based on photon-induced desorption and ionisation in the electric field, is constructed and tested, It also investigates how to show the efficiency of the arrangement adsorbates $H_2$ and He on W(110). The field emitter temperature was 80 K. The wavelength of light used was 193 nm with field strengths between 10 and 50 V/nm. Many ion fragments($CO^+, He^+, H_2^^+, H_2O^+, W^{3+}\; and\; W^{2+}$) were produced by an electronic stimulation of the adsorbate with the help of a photon energy of 6.4 eV at He and $H_2$/W(110). A transient recorder enables the registration of the entire mass spectrum.

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The Study on the Composition of Rehmanniae Radix Extracts by Supercritical Carbon Dioxide Extraction and by Hydrodistillation Extraction (생지황(生地黃) 증류 추출 약침액과 초임계 유체 추출물의 성분 연구(硏究))

  • Heo, Jong-Won;Yook, Tae-Han
    • Journal of Acupuncture Research
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    • v.28 no.2
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    • pp.89-95
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    • 2011
  • Objectives : The purpose of this study was to investigate the composition of Rehmannia glutinosa's essential oils with Rehmanniae Radix herbal acupuncture Methods : I obtained the essential oils of Rehmannia Radix by hydrodistillation extraction method and supercritical fluid extraction(SFE) method, and then I analyzed those by GC/MS(gas chromatography/mass spectrum). Results : 1. With GC(gas chromatography) and GC/MS(gas chromatography/mass spectrum) analysis. I identified 9 compounds in the Rehmanniae Radix's essential oil obtained through the SFE method. The main compounds were as follows : Hexachloroethane(2.24%), N-Butyl-benzenesulfonamide(2.05%), hexadecanoic acid(1.93%), hexadecanoic acid, ethyl ester(3.49%), 9,12-Octadecadienoic acid(z,z)(2.70%), (9E)-9-Octadecenoic acid(6.14%), ethyl linoleate(4.43%), ethyl oleate(5.80%). 2. I failed to get Rehmanniae Radix's essential oil obtained through the hydrodistillation method. 3. With GC(gas chromatography) and GC/MS(gas chromatography/mass spectrum) analysis. I identified 4 compounds in the Rehmanniae Radix's essential oil obtained through the hydrodistillation method. The main compounds were as follows : Ethylbis(trimethylsilyl)amine(1.04%), 2-(Trimethylsiloxy)benzoic methyl ester(2.65%), Hexadecanoic acid trimethylsilyl ester(12.61%), octadecanoic acid, trimethylsilyl ester(6.28%). Conclusions : The substances by hydrodistillation method may not perfectly match with the substances by supercritical fluid extraction(SFE) method in essential oils extracted form Rehmanniae Radix. But, the main substances was assumed Hexadecanoic acid and octadecanoic acid.

Improvement of Spectrum Detection Algorithm for Mass Spectrometer (질량분석기를 위한 스펙트럼 검출 알고리즘의 개선)

  • Lee, Young Hawk;Choi, Hun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.23 no.1
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    • pp.47-54
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    • 2019
  • An improved method of spectrum detection algorithm for mass spectrum analysis system is proposed. In the conventional spectrum detection algorithm that utilizes the results of the linear approximation and quadratic curve fitting on the ion signal block of each mass index, it is possible to reduce the detection error in the mass spectrum detection by further improving the condition of eliminating the invalid ion signals. Also, the proposed method can reduce the estimation error of the peak value of the mass spectrum by using the result of quadratic curve fitting for the effective ion signal block in which the peak position error is corrected. To evaluate the effectiveness of the proposed method, computer simulations were carried out step by step using the measured ion signal. Also, by comparing the rate of false detection for several inputs, the proposed method showed better detection performance than the conventional method.

Additive Noise Reduction Algorithm for Mass Spectrum Analyzer (질량 스펙트럼 분석기를 위한 부가잡음제거 알고리즘)

  • Choi, Hun;Lee, Imgeun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.1
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    • pp.33-39
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    • 2018
  • An additive noise reduction algorithm for a mass spectrum analyzer is proposed. From the measured ion signal, we first used an estimated threshold from the mode of the measured signal to eliminate background noises with the white Gaussian characteristics. Also, a signal block corresponding to each mass index is constructed to perform a second order curve fitting and a linear approximation to signal block. In this process, the effective signal block composed of only the ion signal can be reconstructed by removing the impulsive noises and the sample signals which are insufficient to be viewed as normal ion signals. By performing curve fitting on the effective signal block, the noise-free mass spectrum can be obtained. To evaluate the performance of the proposed method, a simulation was performed using the signals acquired from the development equipment. Simulation results show the validity of the threshold setting from the mode and the superiority of the proposed curve fitting and linear approximation based noise canceling algorithm.

Noise Reduction Algorithm For The Detection of Fine Ion Signals in Residual Gas Analyzer (잔류가스분석기의 질량 스펙트럼 검출 성능 향상을 위한 잡음제거 알고리즘)

  • Heo, Gyeongyong;Choi, Hun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.68 no.1
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    • pp.102-107
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    • 2019
  • This paper proposes a method to improve the mass spectral detection performance of the residual gas analyzer. By improving the mode estimation method for setting the threshold value and improving the additive noise elimination method, it is possible to detect mass spectrums having low peak values of the threshold level difficult to distinguish from noise. Ion signal blocks for each mass index with noise removed by the improved method are effective for eliminating invalid ion signals based on the linear and quadratic fittings. The mass spectrum can be obtained from the quadratic fitted curves for the reconstructed ion signal block using only the valid 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 method, computer simulations were performed using real ion signals obtained from the residual gas analysis system under development. The simulation results show that the proposed method is valid.

Influence of Sample Preparation Method and Silver Salt Types on MALDI-TOFMS Analysis of Polybutadiene

  • Choi, Sung-Seen;Ha, Sung-Ho
    • Macromolecular Research
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    • v.16 no.2
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    • pp.108-112
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    • 2008
  • Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of nonpolar polymeric materials is affected by the sample preparation as well as the matrix and cationizing agent. This study examined the influence of silver salt types on the MALDI analysis of polybutadiene (PB). Silver trifluoroacetate (AgTFA), silver benzoate (AgBz), silver nitrate ($AgNO_3$), and silver p-toluenesulfonate (AgTS) were used as the silver salts to compare the MALDI mass spectra of PB. The mixture solution of PB and 2,5-dihydroxybenzoic acid (DHB), as a matrix dissolved in THF, was spotted on the sample plate and dried. A droplet of the aqueous silver salt solution was placed onto the mixture. The mass spectrum with AgBz showed the clear $[M+Ag]^+$ ion distribution of PB while the mass spectrum with AgTFA did not show $[M+Ag]^+$ ions but only silver cluster ions. The mass spectra with $AgNO_3$ and AgTS did not show a clear $[M+Ag]^+$ ion distribution. The difference in the formation of $[M+Ag]^+$ ions of PB depending on the silver salts was attributed to the silver cation transfer reaction between the silver salt and the matrix (DHB). The mass spectrum showed a clear $[M+Ag]^+$ ion distribution of PB when the conjugate acid of the silver salt was less acidic than the matrix.

Improvement of protein identification performance by reinterpreting the precursor ion mass tolerance of mass spectrum (질량스펙트럼의 펩타이드 분자량 오차범위 재해석에 의한 단백질 동정의 성능 향상)

  • Gwon, Gyeong-Hun;Kim, Jin-Yeong;Park, Geon-Uk;Lee, Jeong-Hwa;Baek, Yung-Gi;Yu, Jong-Sin
    • Bioinformatics and Biosystems
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    • v.1 no.2
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    • pp.109-114
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    • 2006
  • In proteomics research, proteins are digested into peptides by an enzyme and in mass spectrometer, these peptides break into fragment ions to generate tandem mass spectra. The tandem mass spectral data obtained from the mass spectrometer consists of the molecular weights of the precursor ion and fragment ions. The precursor ion mass of tandem mass spectrum is the first value that is fetched to sort the candidate peptides in the database search. We look far the peptide sequences whose molecular weight matches with precursor ion mass of the mass spectrum. Then, we choose one peptide sequence that shows the best match with fragment ions information. The precursor ion mass of the tandem mass spectrum is compared with that of the digested peptides of protein database within the mass tolerance that is assigned by users according to the mass spectrometer accuracy. In this study, we used reversed sequence database method to analyze the molecular weight distribution of precursor ions of the tandem mass spectra obtained by the FT LTQ mass spectrometer for human plasma sample. By reinterpreting the precursor ion mass distribution, we could compute the experimental accuracy and we suggested a method to improve the protein identification performance.

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