• 분석과학
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• 제30권4호
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• pp.194-204
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• 2017

Direct injection (DI) and solid phase extraction (SPE) methods for the simultaneous determination of pendimethalin (PDM) and dinoseb (DNS) in environmental water have been optimized using the ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. The limits of quantification (LOQs) of PDM and DNS were $0.01{\mu}g/L$ using the DI method and $0.0001-0.0002{\mu}g/L$ using the SPE method. The precision by SPE UPLC-MS/MS was less than 11 % for intra-day and inter-day analyses. When the proposed SPE method was used to analyze two analytes in environmental water, PDM was detected in a concentration range of $0.0002-0.011{\mu}g/L$ in 31 samples of the 114 surface water samples, and DNS was detected in a concentration range of $0.0005-0.045{\mu}g/L$ in 17 samples of the 114 surface water samples analyzed. When the DI method was used to analyze target compounds in the same samples, the detected concentrations of the two analytes were within 21% in samples with concentrations above $0.01{\mu}g/L$. The DI UPLC-MS/MS method can thus be used for the routine monitoring of PDM and DNS in environmental water, and the SPE LC-MS/MS method can be used for the determination of the ultra-trace PDM and DNS residues in environmental water.

• 한국수산과학회지
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• 제54권4호
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• pp.404-410
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• 2021

Although, mouse bioassay for the monitoring of azaspiracids (AZAs) toxins in shellfish has been used previously, the reported method has low sensitivity and it is time-consuming. Recently, there is an interest in the quantitative analysis of AZAs using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The purpose of this study is to verify the simultaneous analysis of AZAs in shellfish and tunicate in Korea using LC-MS/MS. To validate the method, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and repeatability were determined. All standard compounds were analyzed within 7 min. The correlation coefficients (R²) of the standard solution was higher than 0.9995 (within the range of 0.8-10.0 ㎍/L). The LODs and LOQs of AZAs in shellfish were 0.08-0.16 ㎍/kg and 0.23-0.50 ㎍/kg, respectively. The accuracy and precision of the method for determining AZAs in shellfish were 87.1-93.0% and 1.23-4.91%, respectively. Consequently, the verified LC-MS/MS method is suitable to analyze AZAs in shellfish and tunicates in Korea.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.163-171
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• 2021

Emiliania huxleyi is a marine phytoplankton that plays a critical role in global carbon and sulfur cycling. The genome of E. huxleyi has been sequenced, and an in-depth proteomic profile of this organism has been reported. This study analyzed the phosphoproteome of E. huxleyi and identified its changes under calcium-limited conditions. A TiO₂ microcolumn was used for phosphopeptide enrichment, followed by liquid chromatography-tandem mass spectrometry analysis. Overall, we identified 7,010 phosphorylated sites on 3,355 phosphopeptides associated with 2,929 phosphoproteins in E. huxleyi. Quantitative analysis revealed changes in the phosphoproteome in E. huxleyi when ambient conditions changed to calcium-limited conditions, notably the phosphorylation of some transporters was altered. This study provides an overview of protein phosphorylation in E. huxleyi and paves the way for further investigations of its biological functions.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.159-162
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• 2021

The fragmentation pattern of four hindered phenol antioxidants was investigated using ammonium and lithium ions as the additives for ionization. Due to different binding geometries and interactions, they underwent different characteristic fragmentation reactions providing useful complementary information for structural analysis of hindered phenol antioxidants. Ammonium ion adducts were fragmented successively until all t-butyl groups were lost in the form of isobutylene and allowed the estimation of the number of t-butyl groups present in the molecule. Lithium ion adducts produced fragment ions from major backbone cleavage, on the other hand, which provide more crucial information for the identification of detailed backbone structure.

• 분석과학
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• 제32권4호
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• pp.121-130
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• 2019

Alumina is one of the most important ceramic materials because of its useful physical and chemical properties. Recently, high-purity alumina has been used in various industrial fields. This leads to increasing demand for reliable elemental analysis of impurities in alumina samples. However, the chemical inertness of alumina makes the sample preparation for conventional elemental analysis a tremendously difficult task. Herein, we demonstrated the feasibility of laser ablation for effective sampling of alumina powder. Laser ablation performs sampling rapidly without any chemical reagents and also allows simultaneous optical emission spectroscopy and mass spectrometry analyses. For six alumina samples including certified reference materials and commercial products, laser-induced breakdown spectroscopy (LIBS) and laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) analyses were performed simultaneously based on a common laser ablation sampling. LIBS was found to be useful to quantify alkali and alkaline earth metals with limits-of-detection (LODs) around 1 ppm. LA-ICP-MS could quantify transition metals such as Ti, Cu, Zn, and Zr with LODs in the range from a few tens to hundreds ppb.

• KSBB Journal
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• 제31권4호
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• pp.263-269
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• 2016

For decades, the microorganisms in arctic soils have been newly discovered according to the climate change and global warming. In this study, the chemical structure of a lipid A molecule from Pseudomonas sp. strain PAMC 28615 which was newly discovered from arctic soils was characterized by mass spectrometric approaches such as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and MALDI multi-stage tandem mass spectrometry (MS). First, lipopolysaccharide (LPS) from Pseudomonas sp. strain PAMC 28615 was extracted and subsequently hydrolyzed to obtain the lipid A. The parent ion peak at m/z 1632 was determined by MALDI-TOF MS, which also can validate our lipid A purification method. For detailed structural determination, we performed the multiple-stage tandem mass analysis ($MS^4$) of the parent ion, and subsequently the abundant fragment ions in each MS stage are tested. The fragment ions in each MS stage were produced from the loss of phosphate groups and fatty acyl groups, which could be used to confirm the composition or the position of the lipid A components. Consequently, the mass spectrometry-based lipid A profiling method could provide the detail chemical structure of lipid A from the Pseudomonas sp. strain PAMC 28615 as an arctic bacterium from the frozen arctic soil.

• Journal of Genetic Medicine
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• 제4권1호
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• pp.53-63
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• 2007

탄뎀 매스를 이용한 신생아 대사 이상 검사는 여과지에 묻힌 소량의 혈액으로 기존의 스크리닝 검사로는 진단되지 않는 30여 종의 아미노산 대사 이상 질환, 유기산 대사 이상 질환, 그리고 여러 지방산 대사 이상 질환을 선별할 수 있는 효과적인 방법이다. 연구자들은 이러한 탄뎀 매스 검사를 집단 선별 검사로 사용하였을 경우 경제적 효용성에 대해 알아보았다. 2001년 4월부터 2004년 3월까지 3년간 총 79,179명의 정상 신생아를 대상으로 탄뎀 매스 검사를 시행하였다. 탄뎀매스 검사를 이용하여 선별 검사를 한 경우, 탄뎀 매스 검사 비용 및 질환이 진단되었을 때의 입원비, 각종 검사료, 특수 분유 비용, 각 질환에 따른 치료비를 합하여 계산하였고, 탄뎀 매스 검사를 시행하지 않은 경우에는 발생한 정신지체아의 보호 양육비 및 이들이 정상적인 생활을 하였을 경우 이들의 노동력을 합한 비용을 계산하여 비교분석하였다. 79,179명의 건강한 신생아 가운데 유전성 대사 이상 질환으로 진단받은 신생아는 총 28명으로 2,827명 당 1명이었다. 이 중 아미노산 대사 이상 질환은 총 13례로 각각 페닐케톤뇨증 4례, tetrahydrobiopterin (BH4) 결손증 2례, 시트룰린혈증 3례, 타이로신혈증 1례, 단풍당뇨증 2례, 고오르니틴혈증-고암모니아혈증-고호모시트룰린혈증증후군(hyperammonemia-hyperornithinemia-homocitrullinemia syndrome, HHH syndrome) 1례가 발견되었고, 유기산 대사 이상 질환은 총 10례로 프로피온산뇨증 4례, 이소발레릭산뇨증 3례, 3-methylcrotonylglycinemia 1례, 글루타릭산뇨증 1형 1례가 발견되었으며, 지방산 대사 이상 질환은 총 5례로 long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) 결손증 3례, very long chain acyl-CoA dehydrogenase (VLCAD) 결손증 1례, short-chain acyl-CoA dehydrogenase (SCAD) 결손증 1례가 발견되었다. 탄뎀 매스 검사를 시행하였을 때와 시행하지 않았을 때 들어가는 총 비용을 비교한 결과, 페닐케톤뇨증은 1:2.26, BH4 결손증은 1:1.68, 시트룰린혈증은 1:3.74, 단풍당뇨증은 1:4.54, 프로피온산뇨증은 1:2.24, 이소발레릭산뇨증은 1:2.66, 글루타린산뇨증 1형은 1:0.39, LCHAD 결손증은 1:5.03로 탄뎀 매스 검사를 시행하는 것이 시행하지 않는 것 보다 경제적 이득이 있는 것으로 나타났으며, 50만 명의 신생아 모두에게 탄뎀 매스 검사를 시행하더라도 전체적으로 1.40배의 경제적 이득이 발생함을 알 수 있었다. 또한 탄뎀 매스 검사는 97.67%의 민감도와 99.28%의 특이도를 나타내었고, 0.05%의 재검률(recall rate)과 6.38%의 양성 예측치를 나타내어 진단적인 가치가 우수함을 알 수 있었다. 유전성 대상 질환에 대한 집단 선별 검사로써의 탄뎀 매스 검사를 시행하는 것이 시행하지 않는 것 보다 경제적임을 알수 있다.

• Mass Spectrometry Letters
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• 제8권2호
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• pp.23-28
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• 2017

Arctigenin is the main active ingredient of Fructus Arctii, which has been reported with a variety of therapeutic activities including anti-cancer, anti-inflammation, anti-virus, and anti-obesity effects. In this study, a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of arctigenin in rat plasma. The assay utilized a simple protein precipitation with methanol and the mobile phase consisted of 100% methanol and water containing 0.1% formic acid (65:35 v/v). Arctigenin and the internal standard (psoralen) were monitored using a positive electrospray turbo ionspray mode with multiple reaction monitoring transitions of m/z $373.2{\rightarrow}136.9$ and m/z $187.2{\rightarrow}130.9$, respectively, and total chromatographic run time was within 5 min. The lower limit of quantification (LLOQ) of arctigenin was 5 ng/mL in the rat plasma. The intra- and inter-day accuracy of arctigenin at LLOQ and matrix-matched quality control samples ranged 97.4 - 104.8% and 97.2 - 102.0%, respectively. The intra-day precision was within 4.80% and the inter-day precision was within 5.92%. Application of the present method was demonstrated through a pharmacokinetic study after intravenous and oral administration of arctigenin in male Sprague Dawley rats.

• Mass Spectrometry Letters
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• 제5권4호
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• pp.104-109
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• 2014

Nonmedical use of prescription stimulants such as methylphenidate (MPH) and amphetamine (AP) by normal persons has been increased to improve cognitive functions. Due to high potential for their abuse, reliable analytical methods were required to detect these prescription stimulants in biological samples. A direct injection liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and implemented for simultaneous determination of MPH, AP and their metabolites ritalinic acid (RA) and 4-hydroxyamphetamine (HAP) in human urine. Urine sample was centrifuged and the upper layer ($100{\mu}L$) was mixed with $800{\mu}L$ of distilled water and $100{\mu}L$ of internal standards ($0.2{\mu}g/mL$ in methanol). The mixture was then directly injected into the LC-MS/MS system. The mobile phase was composed of 0.2% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Capcell Pak MG-II C18 ($150mm{\times}2.0mm$ i.d., $5{\mu}m$, Shiseido) column and all analytes were eluted within 5 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve and the assay was linear from 20 to 1500 ng/mL (HAP), 40-3000 ng/mL (AP and RA) and 2-150 ng/mL (MPH). The intra- and inter-day precisions were within 16.4%. The intra- and inter-day accuracies ranged from -15.6% to 10.8%. The limits of detection for all the analytes were less than 4.7 ng/mL. The suitability of the method was examined by analyzing urine samples from drug abusers.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1791-1800
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• 2004

Angiotensin I, a model decapeptide, was glycosylated and partially hydrolyzed with HCl (6 N, 80 $^{\circ}C$, 4 h), aminopeptidase, and carboxypeptidase Y. A single peptide mass map obtained from truncated peptides in the partial acid hydrolysate of angiotensin and its glycosylation product mixture by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry enabled sequencing of angiotensin by a combinatorial procedure. MALDI-TOF and electrospray ionization (ESI) tandem mass spectrometric results indicate that both the N-terminal amino group of aspartic acid and the guanidinium group of the second residue arginine are glycosylated.