• Title/Summary/Keyword: Expanded relative uncertainty

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Estimation on the application of Reference Materials for PCBs Proficiency Testing from the transformer oil (폐절연유를 이용한 숙련도 평가용 PCBs 표준물질의 적용성 평가)

  • Kim, Woo-Il;Kwon, Myung-Hee;Jeon, Tae-Wan;Kim, Dong-Hoon;Chun, Jin-Won;Sim, Ki-Tae;Yeon, Jin-Mo
    • Analytical Science and Technology
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    • v.23 no.3
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    • pp.247-254
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    • 2010
  • This study was carried out to produce Reference Materials (RMs) for Proficiency Testing (PT) of PCBs in waste analytical laboratories. Two RMs were prepared from used transformer oil samples and PCB free transformer oil by spiking PCBs standard solutions. The spiked PCB RMs were homogenized by mixing and settling up to 90 days. Homogenized concentration of PCBs with Arochlor 1254 (6 ppm), 1254:1260 (1:1) (5 ppm) were observed in 60 days stationary phase but Arochlor 1260 (3.5 mg/L) were observed in 90 days stationary phase. One-way ANOVA test were carried out and showed that the RMs were suitably homogenized, which can be used for proficiency testing. The Relative Standard Deviations (RSDs) of analytical results were 3.51~5.01% for the PCBs RMs in 10 replicates. The expanded uncertainty of PCBs analytical procedure were 0.26~0.49.

Analysis of sorbic acid in tea-drink using isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) (동위원소희석 액체 크로마토그래피-질량분석법을 이용한 차음료 중의 소르빈산의 분석)

  • Ahn, Seong-Hee;Lee, In-Sun;Kim, Byung-Joo
    • Analytical Science and Technology
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    • v.25 no.1
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    • pp.25-32
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    • 2012
  • Isotope dilution mass spectrometry (ID-MS) based on liquid chromatography tandem mass spectrometry (LC/MS/MS) was developed for the accurate determination of sorbic acid in tea-drink. An isotope analogue of sorbic acid, $^{13}C_2$-sorbic acid, was obtained by custom synthesis. MS was operated in the negative mode with selected reaction monitoring (SRM) mode of $[M-H]^-$ ${\rightarrow}$ $[M-CO_2H]^-$ channel at m/z 111 ${\rightarrow}$ 67 for sorbic acid and at m/z 113 ${\rightarrow}$ 68 for its isotope analogue. Chromatographic separation was accomplished with a C18 column and an isocratic mobile phase of 55% of 50 mM ammonium acetate (pH 4.5) and 45% of methanol. Homogeneous reference materials were prepared for validation of this method, including repeatability and reproducibility tests, by fortifying tea-drink with sorbic acid in our laboratory. Repeatability and reproducibility studies showed that the ID-LC/MS method is a reliable and reproducible method which provides less than 3.8% of relative standard deviation (RSD) for the analysis of sorbic acid.