• 분석과학
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• 제12권6호
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• pp.550-557
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• 1999

본 연구에서는 209종의 PCBs 이성체중 독성등가계수(Toxic Equivalance Factor, TEF)가 제시된 13종의 toxic-PCBs에 대하여 Isotope dilution HRCC/HRMS 방법으로 저니토중의 toxic-PCBs를 분석하였다. 분석결과 surrogate 표준물질의 회수율은 71~99%로 양호하였다. 13종의 toxic-PCBs 농도는 0.84~2.49 ng/g 범위이었으며, 이중 2,2',3,3',4,4',5-HpCB(IUPAC No. 170) 및 2,2',3,4,4',5,5'-HpCB(IUPAC No. 180) 농도가 전체 농도의 50% 정도를 나타내었으며, 2,3,4,4,5-PeCB(IUPAC No. 114)도 10% 정도를 나타내었다. 독성등가계수로 환산한 농도는 0.38~2.63 pg-TEQ/g 범위이었으며, 3,3',4,4',5-PeCB(lUPAC No. 126)가 전체의 50%를 나타내었다.

• 대한화학회지
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• 제63권5호
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• pp.387-391
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• 2019

• Mass Spectrometry Letters
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• 제5권2호
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• pp.52-56
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• 2014

Glycated hemoglobin (HbA1c) is used as an index of mean glycemia over prolonged periods. This study describes an optimization of enzyme digestion conditions for quantification of non-glycated hemoglobin (HbA0) and HbA1c as diagnostic markers of diabetes mellitus. Both HbA0 and HbA1c were quantitatively determined followed by enzyme digestion using isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) with synthesized N-terminal hexapeptides as standards and synthesized isotope labeled hexapeptides as internal standards. Prior to quantification, each peptide was additionally quantified by amino acid composition analysis using ID-LC-MS/MS via acid hydrolysis. Each parameter was considered strictly as a means to improve digestion efficiency and repeatability. Digestion of hemoglobin was optimized when using 100 mM ammonium acetate (pH 4.2) and a Glu-C-to-HbA1c ratio of 1:50 at $37^{\circ}C$ for 20 h. Quantification was satisfactorily reproducible with a 2.6% relative standard deviation. These conditions were recommended for a primary reference method of HbA1c quantification and for the certification of HbA1c reference material.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.205-209
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• 2001

Uniformly-doped silicon thin films were fabricated by ion beam sputter deposition. The thin films had four levels of copper dopant concentration ranging between 1 ${\times}$1019 and 1 ${\times}$ 1021 atoms/cm3 . Concentrations of Copper dopants were determined by the isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) to provide certified reference data for the quantitative surface analysis by secondary ion mass spectrometry (SIMS). The copper-doped thin films were dissolved in a mixture of 1 M HF and 3 M HNO3 spiked with appropriate amounts of 65 Cu. For an accurate isotope ratio determination, both the detector dead time and the mass discrimination were appropriately corrected and isobaric interference from SiAr molecular ions was avoided by a careful sample pretreatment. An analyte recovery efficiency was obtained for the Cu spiked samples to evaluate accuracy of the method. Uncertainty of the determined copper concentrations, estimated following the EURACHEM Guide, was less than 4%, and detection limit of this method was 5.58 ${\times}$ 1016 atoms/cm3.

• Mass Spectrometry Letters
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• 제1권1호
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• pp.29-32
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• 2010

Cross reacting antibodies can cause an overestimation of the results of immunoassays. Therefore, alternative methods are needed for the accurate quantification of steroids. Gas chromatography combined with isotope-dilution mass spectrometry (GC-IDMS) is developed to quantify urinary active androgens, testosterone, epitestosterone and dihydrotestosterone, which are clinically relevant androgens to both hair-loss and prostate diseases. The method devised involves enzymatic hydrolysis with $\beta$-glucuronidase, solid-phase extraction, liquid-liquid extraction using methyl tert-butyl ether and subsequent conversion to pentafluorophenyldimethylsilyl-trimethylsilyl (flophemesyl-TMS) derivatives for sensitive and selective analysis in selected-ion monitoring mode. Flophemesyl-TMS derivatization not only eliminates matrix interference but also has a good peak resolution within a 6 min-run. A selective and sensitive GC technique with flophemesyl-TMS derivatives also allows accurate quantitative analysis of three active androgens when combined with IDMS. The limit of quantification of the three analytes was <50 pg/mL, and extraction recoveries ranged from 91.9 to 102.1%. The precision and accuracy were 1.2~6.5% and 89.0~106.7%, respectively. This GC-IDMS method can be useful for evaluating the drug efficacy and monitoring the biological processes responsible for male-pattern baldness and prostate diseases.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3228-3232
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• 2010

Malachite green (MG) has been used world-widely in aquaculture as a parasiticide or fungicide. Although MG performed successfully, it has not been permitted for use in aquaculture from European Union, USA, and Canada because of its carcinogenicity and mutagenicity. We developed a sensitive and specific method to determine MG and its principal metabolite, leucomalachite green (LMG), respectively by isotope dilution liquid chromatography mass spectrometry (ID-LC/MS). To enhance the extraction recovery of MG and LMG from fish tissue, an additional step, saponification, was introduced in sample preparation process to remove fat in sample extract, which hampered the performance of SPE columns. The residue of MG and LMG in fish was analyzed using liquid chromatography mass spectrometry in the selected ion monitoring (SIM) mode by monitoring at m/z 329 and 334 for MG and $d_5$-MG and at m/z 331 and 337 for LMG and $^{13}C_6$-LMG, respectively. This method was validated by comparing with the value of the reference material provided by Laboratory Government Chemistry (LGC). The results agreed within the measurement uncertainty and the accuracy was much improved than the provided reference value by LGC.

• 분석과학
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• 제27권6호
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• pp.269-276
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• 2014

후 컬럼 동위원소 희석법의 불확도를 HPLC-ICP/MS에서 Selenomethionine을 분석할 경우에 대하여 간단히 연구하였다. 주요하다고 생각한 오차의 원인으로 셀레늄 동위원소 용액의 농도와 흐름속도, 스파이크 용액과 시료 용액에서의 셀레늄 원자량, 그리고 스파이크된 시료용액에서 측정된 동위원소의 비를 선택하였다. 각 요인에 따른 불확도를 구하고 전체 농도의 불확도에 미치는 요인을 계산한 결과, 각각에 대하여 54.4%와 0.61%, 0.0072%와 0.018%, 그리고 45.0%를 얻었다. 가장 큰 요인은 스파이크 동위원소 용액의 농도이며 두 번째는 스파이크가 첨가된 시료용액에서의 동위원소비이었다. 스파이크 용액의 질량흐름속도와 원자량의 불활도는 크게 영향을 끼치지 못하였다. 계산된 전체불확도는 $126.30ng{\cdot}g^{-1}$ SeMet 표준용액에 대하여 $1.46ng{\cdot}g^{-1}$으로서 실험결과는 $127.09ng{\cdot}g^{-1}$을 얻었고 상대불확도는 1.20%이었다.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.363-367
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• 2009

An isotope-dilution flow-injection electrospray/mass spectrometric method was developed for the accurate determination of glucosamine contents in pharmaceutical formulations. Samples were extracted by methanol. After spiking glucosamine-1-$^{13}C_1$ as an internal standard, the extracts were then analyzed by flow-injection ESI/MS in a selected ion monitoring (SIM) mode to detect [M+H]$^+$ ions of the analyte and its isotope analogue at m/z 180 and m/z 181, respectively. Confirmatory measurements were made by selectively monitoring the collisionally induced dissociation channels of m/z 180 $\rightarrow$ m/z 72 and m/z 181 $\rightarrow$73, respectively, to test the possibility of bias in the SIM method due to matrix interferences, but any significant bias in the SIM mode was not observed. Repeatability and reproducibility studies showed that the flow-injection ESI/MS method is a reliable and reproducible method which can provide a typical method precision of 1.0 %. Other results for the method validation are reported.

• 암석학회지
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• 제10권3호
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• pp.190-201
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• 2001

동위원소희석법은 스파이크(농축 동위원소)를 사용하여, 질량분석기에서 얻어지는 각 원소들의 동위원소 스펙트럼을 비교함으로써 정량화하는 방법으로서, 현재까지 개발된 정량분석 방법 중 가장 정확한 방법이다. 특히 열이온 질량분석기(Thermal Ion Mass Spectrometer)를 이용한 동위원소희석법은 현재까지 알려진 분석방법 중 가장 신뢰도가 높은 결과(1% 이내의 정도까지 가능함)를 얻을 수가 있다. 동위원소회석법에 의해 정량분석을 하고자 할 때, 가장 중요한 요인중의 하나로서 스파이크(농축 동위원소)의 선택이다. 회토류원소의 복합 스파이크용액을 만들 때의 개개의 회토류원소의 스파이크는 $^{138}$ $La^{142}$ , $Ce^{145}$ /Nd, $^{149}$ /, $Sm^{151}$ , $Sm^{151}$Eu, $^{157}$ Gd, $^{163}$ Dy, $^{167}$ Er, $^{171}$ , $Yb^{176}$ Lu를 많이 쓴다. 이 동위원소희석법에 의한 정량분석이 가장 유용하게 쓰여지고 있는 지구화학적 연구분야는 암석이나 광물의 연대를 측정하고자 할 때의 관심원소의 정량 및 자연계시료의 회토류 원소의 미세구조를 들 수가 있다. 특히 희토류원소의 테트라드 효과를 연구하고자 할 때, 이 동위원소희석법은 아주 효과적인 방법이다.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3663-3667
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• 2010

Acetaminophen (N-acetyl-p-aminophenol) is one of the most popular analgesic and antipyretic drugs. An isotope dilution mass spectrometric method based on LC/MS was developed as a candidate reference method for the accurate determination of acetaminophen in pharmaceutical product. After spiking an isotope labeled acetaminophen (acetyl-$^{13}C_2$, $^{15}N$-acetaminophen) as an internal standard, tablet extracts were analyzed by LC/MS in a selected reaction monitoring (SRM) mode to detect ions at m/z $152{\rightarrow}110$ and m/z $155{\rightarrow}111$ for acetaminophen and acetyl-$^{13}C_2$, $^{15}N$-acetaminophen, respectively. The repeatability and reproducibility of the developed ID/LC-MS method were tested for the validation and assessment of metrological quality of the method.