• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.696-700
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• 1993

Gold bonding wire of 0.076 mm in diameter used in semiconductor industry, is dissoved in aqua regia. The solution is then evaporated to near dryness several times with a few drops of HCl added to prepare the final sample solution in 5% HCl. The gold matrix is separated from trace impurities by controlled potential deposition. The whole electrolysis has been carried out inside a clean bench. An optimum potential is found to be +0.25 V to give more than 99.9% Au matrix removal with better than 90 analytes remaining in the electrolyte solution. Isotope dilution calibration is employed to get the best accuracy and precision. Analytical results are presented with determination limits of the analytical method.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2867-2873
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• 2020

In reprocessed uranium, derived from an impoverished fuel of light-water moderated reactors, there are isotopes of ^{232, 234, 236}U, which make its recycling remarkably difficult. A method of concentration of ²³⁵U target isotope in cascade's additional product was proposed to recover the isotopic composition of reprocessed uranium. A general calculation procedure is presented and a parameters' optimization of multi-flow cascades with additional products. For the first time a numeric model of a cascade that uses the cuts of partial flows of stages with relatively high separation factors was applied in this procedure. A novel computing experiment is carried out on separation of reprocessed uranium hexafluoride with providing a high concentration of ²³⁵U in cascade's additional product with subsequent dilution. The parameters of cascades' stages are determined so as to allow reducing the ^{232, 234, 236}U isotope content up to the acceptable. It was demonstrated that the dilution of selected products by the natural waste makes it possible to receive a low enriched uranium hexafluoride that meets the ASTM C996-15 specification for commercial grade.

• Bulletin of the Korean Chemical Society
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• 제26권3호
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• pp.440-446
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• 2005

A method is described for the determination of dibutyltin (DBT) in sediment by isotope dilution using liquid chromatography inductively-coupled plasma/mass spectrometry (LC-ICP/MS). To achieve the highest accuracy and precision, special attentions are paid in optimization and evaluation of overall processes of the analysis including extraction of analytes, characterization of the standards used for calibration and LC-ICP/MS conditions. An approach for characterization of natural abundance DBT standard has been developed by combining inductively-coupled plasma/optical emission spectrometry (ICP/OES) and LC-ICP/MS for the total Sn assay and the analysis of Sn species present as impurities, respectively. An excellent LC condition for separation of organotin species was found, which is suitable for simultaneous DBT and tributyltin (TBT) analysis as well as impurity analysis of DBT standards. Microwave extraction condition was also optimized for high efficiency while preventing species transformation. The present method determines the amount contents of DBT in sediments with expanded uncertainty of less than 5% and its result shows high degree of equivalence with reference values of an international inter-comparison and a certified reference material (CRM) within stated uncertainties.

• 분석과학
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• 제31권6호
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• pp.225-231
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• 2018

안식향산, 메틸파라벤, 부틸파라벤은 식품, 의약품뿐 만 아니라 화장품 분야에서도 사용되는 보존료이다. 그러나 이들 보존료들의 여러 가지 독성이 보고되면서, 한국을 비롯하여 여러 나라들에서 식품 중의 이들 보존료의 사용을 규제하고 있다. 본 연구에서는 간장 중의 안식향산, 메틸파라벤, 부틸파라벤의 정확하고 정밀한 분석을 위하여 세가지 분석물질의 동위원소를 내부표준물질로 이용하는 동위원소 희석 액체크로마토그래피 질량분석법 (Isotope Dilution Liquid Chromatography Mass Spectrometry, ID-LC/MS)을 개발하였다. 메틸, 부틸 파라벤보다 pKa가 낮은 안식향산을 고려하여 acetic acid로 pH 4.0으로 조정한 5 mM ammonium acetate를 이동상 용매로 사용하여 C18 컬럼으로 분리하였다. 질량분석 조건으로는 전기분무이온화법으로 음이온을 생성하여 음이온 모드에서 분석하였으며, 방해물질로부터 선택성을 향상하기 위해 선택반응분석법 (Selected Reaction Monitoring)을 이용하여 분석하였다. 간장의 색깔과 간장 중의 여러 가지 방해물질들을 제거하기 위하여 C18 카트리지를 이용하여 정제하였다. 최적화된 조건과 방법을 이용하여 싱가포르 Health Science Authority(HSA)가 제공하는 간장 기준시료를 분석하였다. 본 연구원에서 측정한 결과값은 HSA가 제공하는 기준값과 불확도 내에서 일치하였다.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1149-1154
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• 2010

Liquid chromatography/mass spectrometry using isotope dilution method has been established as a primary method for the measurement of cortisol in human serum. Verification of this method was accomplished by the participation in Consultative Committee for Amount of Substance-Metrology in Chemistry (CCQM) pilot study. Two levels of cortisol certified reference materials were prepared and certified by the established method. They were used as sample materials for the proficiency testing. The expanded uncertainty in the measurement of cortisol in human serum was approximately 1.2% at 95% confidence level. The results of the proficiency testing showed a good precision among the participants, but some bias to the certified values. This means that commercial field laboratories should keep traceability chain to SI unit through available reference measurement procedures and/or available reference materials.

• 한국초지조사료학회지
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• 제36권4호
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• pp.318-324
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• 2016

본 연구는 전남농업기술원 답리작 시험포장에서 2006년과 2007년 사이에 보리와 이탈리안 라이그래스와 각종 두과를 혼파비율을 달리한 처리하여 파종하였다. 주구는 보리 및 이탈리안 라이그래스와 자운영, 크림손클로버, 헤어리벳치, 사료용 완두였고 세구는 화본과와 두과를 각각 50:50, 60:40, 70:30 그리고 80:20이었다. 공중질소 고정량 및 이의 이동을 측정하기 위하여 질소동위원소($^{15}N(NH_4)_2SO_4$)를 2007년 4월 15일 처리 후 쿼드랏 안의 식물체를 6월 8일에 수확하여 화본과 및 두과로 분리한 후 안정성동위원소 질량분석기를 이용하여 분석하였다. 공중질소 고정률은 두과에서 화본과로, 질소이동은 차이법과 동위원소 희석법을 이용하여 구하였다. 본 실험결과의 주요내용은 동위원소 초과는 화본과에서는 차가 없었던 반면 보리와 두과와 혼파비율이 60:40인 처리에서 유의적인 차이가 있었다. 그 값은 보리와 혼파한 두과는 0에서 0.54 범위였다. 이탈리안 라이그래스와 두과 혼파에서는 초과 값이 더 높아 보리에서는 0.71에서 0.82, 두과는 0.37에서 1.01 사이였다. 공중 질소 이용비율은 보리와의 조합은 0%~49.5%, 이탈리안 라이그라스 조합은 0~60.5%의 범위로 다양한 결과를 나타내었다. 차이법에 의한 이동량 시험에서는 보리와의 조합에서 12.3~90.9 kg/ha, 이탈리안 라이그래스 조합에서는 보리보다 더 많아 31.7~107.8 kg 사이였다. 한편 동위원소 희석법에서는 보리와 두과 혼파조합은 0~36.1 kg/ha 그리고 이탈리안 라이그래스와 두과 혼파에서는 0~50.6 kg/ha로 이탈리안 라이그래스 조합이 더 많은 것으로 나타났다. 차이법에 의한 질소 이동량이 동위원소 희석법보다 더 많은 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.737-744
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• 2007

An isotope dilution-liquid chromatography/tandem mass spectrometric method was developed as a candidate reference method for the accurate determination of acrylamide in potato chips, starch-rich foodstuff cooked at high temperature. Sample was spiked with 13C3-acrylamide and then extracted with water. The extract was further cleaned up with an Oasis HLB solid-phase extraction (SPE) cartridge and an Oasis mixed-phase cation exchange (MCX) SPE cartridge. The extract was analyzed by using LC/ESI/Tandem MS in positive ion mode. LC with a medium reversed-phase (C4) column was optimized to obtain adequate chromatographic retention and separation of acrylamide. MS was operated to selectively monitor [M+H]+ ions of the analyte and its isotope analogue at m/z 72 and m/z 75, respectively. Sample was also analyzed by the LC/MS with selectively monitoring the collisionally induced dissociation channels of m/z 72 → m/z 55 and m/z 75 → 58. Compared to the LC/MS chromatograms, the LC/MS/MS chromatograms showed substantially reduced background chemical noises coming from solvent clusters formed during ESI spray processes and interferences from sample matrix. Repeatability and reproducibility studies showed that the LC/MS/MS method is a reliable and reproducible method which can provide a typical method precision of 1.0% while the LC/MS results are influenced by chemical interferences.

• Mass Spectrometry Letters
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• 제8권3호
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• pp.53-58
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• 2017

Glycated hemoglobin ($HbA_{1c}$) has been commonly used to screen and diagnose for patients with diabetes mellitus. Here the accelerated procedure of microwave-assisted sample treatment from acid hydrolysis to enzyme digestion followed by isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) was optimized and applied to measure $HbA_{1c}$ in an effort to speed up analysis time. First, two signature peptides of $HbA_{1c}$ and hemoglobin $A_0$ were certified with amino acid analysis by setting optimized acid hydrolysis conditions to $150^{\circ}C$, 1.5 h and $10{\mu}M$ sample concentration in 8 M hydrochloric acid. Consequently, the accurate certified peptides above were used as calibration standards to implement the proteolytic procedure with endoproteinase Glu-C at $37^{\circ}C$, 700 W for 6 h. Compared to the traditional method, the microwave heating not only shortened dramatically sample preparation time, but also afforded comparable recovery yields. The optimized protocol and analytical conditions in this study are suitable for a primary reference method of $HbA_{1c}$ quantification with full SI-traceability and other similar proteins in complex biological samples.

• 한국유기농업학회지
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• 제19권spc호
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• pp.161-164
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• 2011

Nitrogen fixation by legumes can be valuable sources for organic farming. This study was to investigate the effect of different legume mixtures on nitrogen fixation and transfer to grasses on spring paddy field. Three different mixtures were used (rye+hairy vetch, Italian ryegrass+crimson clover, oat+pea) in a randomized complete block design with three replications and sowed in pots with different sowing rate (5:5 rye:hairy vetch,7:3=Italian:crimson, 6:4=oat:pea) on early March. $(^{15}NH_4)SO_4$ solution at. 99.8 atom%$^{15}N$ was applied to the each pot at the rate of 2kg N $ha^{-1}$ on $16^{th}$ April. Forage were harvested at ground level in heading stage and separated into legume and grass. Total N content and $^{15}N$ value were determined using a continuous flow stable isotope ratio mass spectrometry. DM yield of rye+vetch, Italian+crimson and oat+pea were 6,607, 3,213 and 4,312kg/ha, respectively. Proportion of N from fixation was 0.73(rye+vetch), 0.42(Italian+crimson) and 0.93(oat+pea). The percentages of N transfer from legume to grass were from 61% to 24% in different method by treatments and -35% to 21% in isotope dilution method.

• 한국해양학회지:바다
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• 제27권3호
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• pp.144-157
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• 2022

비활성기체는 화학적, 생물학적 반응을 하지 않는 보존적인 특성을 가지고 있어 해양에서 수온과 염분 변화, 기체 주입, 해수의 혼합과 빙하 융해수의 분포와 같은 물리적인 변화의 추적자로 활용되고 있다. Ne, Ar과 Kr을 정밀하게 분석하기 위해 사중극자 질량 분석기, 고진공 전처리 라인, 초저온 냉각 트랩과 동위원소 표준기체로 구성된 분석 시스템을 제작했다. 고진공 라인은 시료의 용존 기체를 추출하여 동위원소 표준기체와 혼합하는 시료추출부, 합금 물질을 이용하여 반응성 기체를 제거하고 초저온 냉각 트랩으로 비활성기체를 기화점에 따라 분별 증류하는 기체 준비부, 비활성기체를 원소별로 측정하는 기체 측정부로 구성하였다. 기체준비부에 결합한 초저온 냉각 트랩은 질량분석기 내 Ar와 CO₂의 부분압을 현저히 낮추어 Ne 동위원소 분석의 오차를 감소시켰다. 동위원소 표준기체는 ²²Ne, ³⁶Ar과 ⁸⁶Kr를 혼합하여 제작하였고, 혼합 표준 기체의 원소별 양은 대기를 반복 측정하여 역동위원소 희석법으로 결정했다. 대기 평형수 반복 분석의 상대 오차는 Ne, Ar과 Kr에 대해 각각 0.7%, 0.7%, 0.4%이었다. 반복 측정한 대기 평형수의 농도와 포화 농도의 차이로 확인한 분석시스템의 정확도는 Ne, Ar, Kr에 대해 각각 0.5%, 1.0%, 1.7%이었다.