• Title/Summary/Keyword: Internal standards

Search Result 487, Processing Time 0.025 seconds

Development of Gas Chromatography/Mass Spectrometry for the Determination of Essential Fatty Acids in Food Supplemental Oil Products

  • Ahn, Seonghee;Yim, Yoon-Hyung;Kim, Byungjoo
    • Mass Spectrometry Letters
    • /
    • v.4 no.4
    • /
    • pp.75-78
    • /
    • 2013
  • A gas chromatography/mass spectrometric (GC/MS) method was developed as a candidate reference method for the accurate determination of essential fatty acids (linoleic acid, ${\alpha}$- and ${\gamma}$-linolenic acids) in food supplemental oil products. Samples were spiked with three internal standards (stearic acid-$d_{35}$, $^{13}C_{18}$-linoleic acid, and $^{13}C_{18}$-${\alpha}$-linolenic acid). Samples were then subject to saponification, derivatization for methylation, and extraction by organic solvent. For GC/MS measurement, an Agilent HP-88 column, designed for the separation of fatty acid methyl esters, was selected after comparing with other columns as it provided better separation for target analytes. Target analytes and internal standards were detected by selected ion monitoring of molecular ions of their methyl ester forms. The GC/MS method was applied for the measurement of three botanical oils in NIST SRM 3274 (borage oil, evening primrose oil, and flax oil), and measurement results agreed with the certified values. Measurement results for target analytes which have corresponding isotope-labeled analogues as internal standard were calculated based on isotope dilution mass spectrometry (IDMS) approach, and compared with results calculated by using the other two internal standards. Results from the IDMS approach and the typical internal standard approach were in good agreement within their measurement uncertainties. It proves that the developed GC/MS method can provide similar metrological quality with IDMS methods for the measurement of fatty acids in natural oil samples if a proper fatty acid is used as an internal standard.

Selected ion monitoring analysis of conjugated metabolites of methadone using biosynthetic internal standards for the study of methadone-diazepam interaction

  • Kang, Gun-Il
    • Archives of Pharmacal Research
    • /
    • v.6 no.1
    • /
    • pp.7-16
    • /
    • 1983
  • A methadone-diazepam interaction study in rats was performed in which conjugated metabolites of methadone were analyzed using deuterated biosynthetic internal standards. Diazepam (5mg/kg) was given to rats through a cannulate djugular vein and a subcutaneous dose of methadone (10mg/kg) was given. Bile was collecte through the cannulate dbile duct over a period of 24 hours. The deuterium label of the internal standards was found to be stable under conditions of the prolonged incubation. There was no significant difference in the excretion of the metabolites between the control and the diazepam treated rats. Feasibility of using biosynthetic internal standards with selected ion monitoring was established for the drug metabolism and kinetic studies.

  • PDF

ST-T Changes of Multichannel Magnetocardiographic Pattern in Myocardial Ischemia (허혈에 의한 다채널 심자도의 ST-T 변화)

  • Kwon, H.;Kim, K.;Lee, Y.H.;Kim, J.M.;Lim, H.K.;Park, Y.K.;Chung, N.;Ko, Y.G.;Joung, B.;Kim, J.B.;Cho, J.R.
    • Progress in Superconductivity
    • /
    • v.9 no.1
    • /
    • pp.35-39
    • /
    • 2007
  • Myocardial ischemia causes heterogeneity of ventricular repolarization and sometimes produces changes of the ST-T wave in ECG. Therefore, morphological changes of ST-T waveform in ECG have a clinical significance in diagnosing myocardial ischemia. In this study, we investigated the ST-T changes caused by myocardial ischemia in magnetocardiography (MCG). We analyzed MCG patterns of biphasic T, ST segment deviations from baseline, main current angle of $T_{peak}$ and $T_{peak}$ dispersion in 300 CAD patients without ST elevation in ECG, 122 symptomatic patients and 48 normal subjects. MCGs were recorded by multichannel SQUID system in a magnetically shielded room. As results, we found that appearances of the abnormality were strongly correlated with the severity of myocardial ischemia. Also we found that the percentage of the patients showing MCG changes were higher than those in ECG. These results show that morphological changes of ST-T waveform in MCG can be used as a marker of myocardial ischemia.

  • PDF

Development of Inner Pressure Measurement System for Hermetic Sealed Small Components (밀폐된 소형부품의 내부압력 측정장치 개발)

  • Hong, S.S.;Lim, I.T.;Lim, J.Y.
    • Journal of the Korean Vacuum Society
    • /
    • v.21 no.1
    • /
    • pp.1-5
    • /
    • 2012
  • The measurement device of internal pressures of small components sealed hermetically was developed. The internal pressure of a sample measured with this device was 43.151 kPa, and the expanded uncertainty ($\kappa$=2) was 741 Pa. The resultant measurement ability of internal pressures in small vacuum components, which had been almost impossible previously, shows the possibility of internal vacuum detection of hermetically sealed parts.

Current Status of Internal Dosimetry Methods and Radiological Regulations in Korea, Ukraine and European Community

  • Lee, Tae-Young;Lee, Jong-Il;Berkovski, Vladimir
    • Journal of Radiation Protection and Research
    • /
    • v.28 no.1
    • /
    • pp.65-73
    • /
    • 2003
  • The paper discusses results of recent international intercomparison exercises on internal dose assessments, status of up to date internal dosimetry methods and the radiological legislation developed and implemented in Korea, European Union and Ukraine. The system of radiation protection in Korea is based on the Korean Atomic Energy Regulatory Enforcement on Safety Standards (Ministry Notice No. 2001-2). The notice is based on the recommendations in ICRP Publication 60 (1990) and IAEA Basic Safety Standards (1996). But the full implementation of the notice by the end of the year 2002 is not required because of the socio-economic situation and inexperience in internal radiation dosimetry Regulatory framework for internal radiation dosimetry is under development toward the full implementation of the notice from January 1, 2003. The system of radiation protection in Ukraine is based on the National radiation protection regulatory code NRBU-97. The code was developed and adopted in 1998 and replaced the Regulations of Former Soviet Union. The document is based on the ICRP Publication 60, Euratom Directive 96/29 and IAEA Basic Safety Standards (1996). The transitional period of 5 years (effected till January 2003) is established for implementation of all requirements of this new regulation. The system of radiation protection in the European Community is based on the Council Directive 96/29/Euratom, adopted in 1996 and enforced from 13 May 2000. Directive 96/29/Euratom has the status of the European law.

Research on the Non-Contact Detection of Internal Defects in a Rail Using Ultrasonic Waves (비접촉 초음파 방식의 철도레일 내부결함 검출에 관한 연구)

  • Han, Soon-Woo;Cho, Seung-Hyun;Kim, Joon-Woo;Heo, Tae-Hoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.22 no.10
    • /
    • pp.1010-1019
    • /
    • 2012
  • Non-contact detection of internal defects in a rail using ultrasonic waves is discussed in this paper. Cracks in a rail may be the cause of a serious railway accident such as derailment if left undetected. Concurrent rail inspection method based on ultrasonic testing using piezoelectric transducers has several limitations as it should keep physical contact with the rail. This work suggests a non-contact detection of internal defects in a rail using ElectroMagnetic Acoustic Transducers (EMAT) which can produce and measure ultrasonic waves in a rail without any couplant. The EMATs for rail inspection are designed and fabricated and their working performance is verified through a series of experiments on various types of internal defects in test rails. The effect of lift-off between the transducers and the rail on the generated signals is also discussed.

The Impact of Internal Audit Quality on Financial Performance of Yemeni Commercial Banks: An Empirical Investigation

  • HAZAEA, Saddam A.;TABASH, Mosab I.;KHATIB, Saleh F.A.;ZHU, Jinyu;AL-KUHALI, Ahmed A.
    • The Journal of Asian Finance, Economics and Business
    • /
    • v.7 no.11
    • /
    • pp.867-875
    • /
    • 2020
  • Quality internal audit (IA) plays a crucial role in accountability, transparency and preserving public properties. This paper gives a brief background of the IA system in Yemen and examines its impact with regards to financial performance in Yemeni commercial banks based on five factors: (i) independence of IAs, (ii) adherence to IA standards, (iii) governance principles implementation, (iv) size of the IA, and (v) frequency of internal audits committees' meetings. The primary data for the study were collected through a questionnaire prepared for this purpose. Fifty questionnaires were distributed out of which forty-two were retrieved and valid in the analysis process. For the empirical analysis, descriptive analysis and T-test were used for verification of the research hypotheses. Results revealed that sticking to standards internal audit, internal auditors' independence and quality governance have significant impact on banks' financial performance, while the size of internal audits committees, as well as their meeting, frequently has insignificant positive impact on banks' performance. Moreover, the country results show that the use of automated internal audit in banks has an impact on improving financial performance. This article provides avenues for further studies, mainly in developing countries, including Yemen, in quality internal audit and financial performance.

A Study on the control system for the Unintended Car Movement Protection Means to meet the International Standards of lifts

  • Choi, Youngkiu;Lee, Hochul
    • Journal of Electrical Engineering and Technology
    • /
    • v.12 no.5
    • /
    • pp.2079-2087
    • /
    • 2017
  • As the number of tall buildings is increasing, the high-speed lift is necessary in the modern world. Therefore, the further considerations for associated safety devices of lifts were required by the International Standards. In order to stop the moving of cage and keep it, the lifts have to be provided with means that can detect the unintended car movement. Therefore, the International Standard Safety Rules for the construction and installation of lifts had been revised. This paper describes the operation principles of the Rope Brake to fit the Unintended Car Movement Protection (UCMP) means required by the International Standards. This paper confirmed that the performance of these devices was suitable in the scope of the safety standards. This paper also analyzed that the shocks on working of these devices in a car would be dangerous to each passenger differently. Thus, this paper proposes a new design that the circuit diagram of the Unintended Car Movement Protection systems should be improved from the existing design to solve these internal shock problems. So, it is expected to protect passengers from the internal shocks by working of Rope Brake due to irrelevant factors.

Accurate Measurement of Arsenic in Laver by Gravimetric Standard Addition Method Combined with High Resolution Inductively Coupled Plasma Mass Spectrometry

  • Lee, Kyoung-Seok;Kim, Hyeon-Ji;Yim, Yong-Hyeon;Kim, Jeongkwon;Hwang, Euijin
    • Mass Spectrometry Letters
    • /
    • v.5 no.2
    • /
    • pp.57-61
    • /
    • 2014
  • A gravimetric standard addition method combined with internal standard calibration has been successfully developed for the accurate analysis of total arsenic in a laver candidate reference material. A model equation for the gravimetric standard addition approach using an internal standard was derived to determine arsenic content in samples. Handlings of samples, As standard and internal standard were carried out gravimetrically to avoid larger uncertainty and variability involved in the volumetric preparation. Germanium was selected as the internal standard because of its close mass to the arsenic to minimize mass-dependent bias in mass spectrometer. The ion signal ratios of $^{75}As^+$ to $^{72}Ge^+$ (or $^{73}Ge^+$) were measured in high resolution mode ($R{\geq}10,000$) to separate potential isobaric interferences by high resolution ICP/MS. For method validation, the developed method was applied to the analysis of arsenic content in the NMIJ 7402-a codfish certified reference material (CRM) and the result was $37.07mg{\cdot}kg^{-1}{\pm}0.45mg{\cdot}kg^{-1}$ which is in good agreement with the certified value, $36.7mg{\cdot}kg^{-1}{\pm}1.8mg{\cdot}kg^{-1}$. Finally, the certified value of the total arsenic in the candidate laver CRM was determined to be $47.15mg{\cdot}kg^{-1}{\pm}1.32mg{\cdot}kg^{-1}$ (k = 2.8 for 95% confidence level) which is an excellent result for arsenic measurement with only 2.8 % of relative expanded uncertainty.