• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.59.1-59.1
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• 2015

In the Linford group at Brigham Young University we have recently developed three new sets of materials for three different areas of separations science: thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and solid phase microextraction (SPME). First, via microfabrication we have grown patterned carbon nanotube (CNT) forests on planar substrates that we have infiltrated with inorganic materials such as silicon nitride. The coatings on the CNTs are conformal and typically deposited in a process like low pressure chemical vapor deposition. The resulting materials have high surface areas, are porous, and function as effective separation devices, where separations on our new TLC plates are typically significantly faster than on conventional devices. Second, we used the layer-by-layer (electrostatically driven) deposition of poly (allylamine) and nanodiamond onto carbonized poly (divinylbenzene) microspheres to create superficially porous particles for HPLC. Many interesting classes of molecules have been separated with these particles, including various cannabinoids, pesticides, tricyclic antidepressants, etc. Third, we have developed new materials for SPME by sputtering silicon onto cylindrical fiber substrates in a way that creates shadowing of the incoming flux so that materials with high porosity are obtained. These materials are currently outperforming their commercial counterparts. Throughout this work, the new materials we have made have been characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, transmission electron microscopy, etc.

• BMB Reports
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• 제42권7호
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• pp.401-410
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• 2009

We have developed a targeted lipidomics approach that makes it possible to directly analyze chiral eicosanoid lipids generated in cellular systems. The eicosanoids, including prostaglandins (PGs), thromboxanes (TXs), leukotrienes (LTs) and alcohols (HETEs), have been implicated as potent lipid mediators of various biological processes. Enzymatic formations of eicosanoids are regioselective and enantioselective, whereas reactive oxygen species (ROS)-mediated formation proceeds with no stereo-selectivity. To distinguish between enzymatic and non-enzymatic pathways of eicosanoid formation, it is necessary to resolve enantiomeric forms as well as regioisomers. High sensitivity is also required to analyze the eicosanoid lipids that are usually present as trace amounts (pM level) in biological fluids. A discovery of liquid chromatography-electron capture atmospheric pressure chemical ionization/mass spectrometry (LC-ECAPCI/MS) allows us to couple normal phase chiral chromatography without loss of sensitivity. Analytical specificity was obtained by the use of collision-induced dissociation (CID) and tandem MS (MS/MS). With combination of stable isotope dilution methodology, complex mixtures of regioisomeric and enantiomeric eicosanoids have been resolved and quantified in biological samples with high sensitivity and specificity. Targeted chiral lipidomics profiles of bioactive eicosanoid lipids obtained from various cell systems and their biological implications have been discussed.

• Food Science and Biotechnology
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• 제17권5호
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• pp.1032-1037
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• 2008

Lowly volatile heterocyclic sulfur compounds generated in autoclaved garlic extract were isolated and identified, and their antimicrobial activity was determined. Two kinds of unusual volatile sulfur compounds were separated from heated garlic by preparative recycling high performance liquid chromatography (HPLC), and identified by gas chromatography (GC)-mass spectrometry (MS) and $^1H$-nuclear magnetic resonance (NMR). They had heterocyclic structures with 4 to 5 sulfur atoms in the molecules. 4-Methyl-1,2,3-trithiolane (MTTT) is highly volatile and was not able to be concentrated, and was identified by GCMS only. MTTT and 6-methyl-1,2,3,4,5-pentathiepane (MPTP) are lowly volatile and were obtained in pure states to be positively identified for the first time. All 3 heterocyclic sulfur compounds began to appear by the time when the early-formed diallyl sulfides started to disappear. The minimum inhibitory concentration range of MTTT and MPTP was determined to be between 1 and 6 ppm against all yeasts tested. MTTT and MPTP were lowly volatile and sparingly soluble in water.

• 한국식물병리학회지
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• 제10권2호
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• pp.129-135
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• 1994

Ninety-two isolates of Fusarium species were obtained from Chinese corn samples. The predominant Fusarium species isolated from corn seeds were F. moniliforme, F. proliferatum, F. oxysporum and F. subglutinans, and all 13 species were identified. Each isolate was grown on autoclaved wheat grains and wheat cultures were fed by twenty-one-day-old female rats for the toxicity test. Twenty-six out of 92 isolates caused the death accompanying feed refusal, severe weight loss, liver damage, and hemorrhages in the stomach and intestines. Of the toxigenic isolates, 17 isolates of F. moniliforme, 4 of F. oxysporum, 3 of F. proliferatum, and one of each F. sporotrichioides and unknown species were lethal to rats. The analyses of fumonisin B1 production of the 26 toxigenic Fusarium isolates were carried out by thin layer chromatography and high-performance liquid chromatography, and fumonisin B1 was confirmed by mass spectrometry. Fumonisin B1 was produced in wheat culture at levels ranging from 280 $\mu\textrm{g}$/g to 3,952 $\mu\textrm{g}$/g by all of toxigenic F. moniliforme and F. proliferatum, but by none of the other toxigenic Fusarium species. The present results suggest the high possibility of natural occurrence of fumonisin B1 in corn samples imported from China.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2163-2167
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• 2012

A rapid, specific, and reliable LC-MS/MS-based bioanalytical method was developed and validated in rat plasma for the simultaneous quantitation of amitriptyline and its metabolite nortriptyline. Chromatographic separation of these analytes was achieved on a Gemini C18 column ($50{\times}4.60mm$, $5{\mu}m$) using reversed-phase chromatography. The mobile phase was an isocratic solvent system consisting of 1% formic acid in water and methanol (10:90, v/v), at a flow rate of 0.2 mL/min. The analytical range was set as 0.1-500 ng/mL for amitriptyline and 0.08-500 ng/mL for nortriptyline using a $200{\mu}L$ plasma sample. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. The validated method was successfully applied to a pharmacokinetic study in six rats after oral administration of amitriptyline (15 mg/kg). This method allows laboratory scientists to rapidly determine amitriptyline and nortriptyline concentrations in plasma.

• Mycobiology
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• 제47권3호
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• pp.292-300
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• 2019

IAA biosynthetic pathways in a basidiomycetous yeast, Rhodosporidiobolus fluvialis DMKU-CP293, were investigated. The yeast strain showed tryptophan (Trp)-dependent IAA biosynthesis when grown in tryptophan supplemented mineral salt medium. Gas chromatography-mass spectrometry was used to further identify the pathway intermediates of Trpdependent IAA biosynthesis. The results indicated that the main intermediates produced by R. fluvialis DMKU-CP293 were tryptamine (TAM), indole-3-acetic acid (IAA), and tryptophol (TOL), whereas indole-3-pyruvic acid (IPA) was not found. However, supplementation of IPA to the culture medium resulted in IAA peak detection by high-performance liquid chromatography analysis of the culture supernatant. Key enzymes of three IAA biosynthetic routes, i.e., IPA, IAM and TAM were investigated to clarify the IAA biosynthetic pathways of R. fluvialis DMKU-CP293. Results indicated that the activities of tryptophan aminotransferase, tryptophan 2-monooxygenase, and tryptophan decarboxylase were observed in cell crude extract. Overall results suggested that IAA biosynthetic in this yeast strain mainly occurred via the IPA route. Nevertheless, IAM and TAM pathway might be involved in R. fluvialis DMKU-CP293.

• 한국식품영양학회지
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• 제28권1호
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• pp.143-152
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• 2015

Vitamin D contents in agricultural products and foods were quantified by high performance liquid chromomatography (HPLC) with a UV/Vis detector, using external standard methods. The results were confirmed with liquid chromatography tandem mass spectrometry (LC-MS/MS). After homogenization, samples were hydrolyzed by direct alkali saponification. Thereafter, fat-soluble components were extracted with n-hexane containing 0.01% butylated hydroxytoluene (BHT). Vitamin D contents in cereals were found to be in the range of $1.882{\sim}4.856{\mu}g/100g$. Juda's ear and oak mushroom contained high amounts of vitamin D, at 363.85 and $199.42{\mu}g/100g$ of edible portion, respectively.

• 생명과학회지
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• 제11권1호
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• pp.35-42
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• 2001

Irradiation-induced volatile flavor compounds in irradiated (0, 1, 3, 5, 10 kGy) pork meats were analyzed by liquid liquid continuous extraction (LLCE) and gas chromatography/mass spectrometry (GC/MS) methods. One hundred nine volatile compounds were detected in irradiated pork meats. These compounds were mainly composed of hydrocarbons (42 compounds), aromatic compounds (39), aldehydes(9), ketones(5) and miscellaneous compounds (14). Among these, three volatile compounds, such as decene, 1,2,3,4,-tetrahydro-6-methylnaphthalene and 1,2,3,4-tetrahydro-dimethylnaphthalene were selected as irradiation-induced compounds comparing with irradiation dosages in irradiated pork meats. By the high correlation coefficient with the increment of irradiation dose, however, decene (r=0.93) was considered as marker compound for detecting irradiation dosage in fresh pork meats.

• 한국지역사회생활과학회지
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• 제23권2호
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• pp.199-206
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• 2012

In order to evaluate the aroma compounds in Korean traditional alcoholic beverages, volatile compounds of the commercial wines, Makgeolli were analyzed and quantified using the conventional method. Eight volatile compounds including three kinds of alcohols, two kinds of organic acids and three kinds of ether were extracted by Liquid-Liquid Extraction with Dichloromethane. For the separation and quantification, Gas chromatography coupled with mass spectrometry (GC/MS) was used to analyze these compounds. Also, the separation efficiency of these compounds was performed and compared with GC column. The results of this study were as follows ; Eight kinds of volatile compounds were separated well on the HP-88 column better than on the DB-5MS column. Short chain fatty acids, butyric acid and isovaleric acid were not detected in two brands of makgeolli samples. The higher alcohols were detected in the range of 0.86~225.68 ${\mu}g/mL$ and ethyl esters were detected in the range of 0.86~225.68 ${\mu}g/mL$, respectively. There compounds are known to be associated with sensory and odorant.

• 한국식품과학회지
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• 제41권3호
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• pp.326-333
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• 2009

국내에서 주로 섭취되는 어패류(고등어, 삼치, 조기, 대합, 바지락, 꼬막, 백합)를 가열조리 하였을 때 형성되는 HCAs를 분리, 동정하여 그 함량을 모니터링 하였다. 추출 및 정제는 고체상 추출 방법을 사용하였고 정성, 정량을 위한 분석장비는 LC/MS를 사용하였다. 모니터링 결과 생선류에서는 고등어(2.2-1,1117.7 ng/g), 삼치(9.1-443.6 ng/g), 조기(17.5-179.5 ng/g)순으로 HCAs가 많이 검출되었으며 특히 고등어 muscle에서 많은 양(1,1117.7 ng/g, Harman)이 검출되었다. 조개류 중에서는 대합(12.2-196.4 ng/g), 꼬막(2.2-76.2 ng/g), 바지락(1.7-25.8 ng/g), 백합(1.5-2.7 ng/g)순으로 많이 검출되었으며 대합의 Norharman(196.4 ng/g)이 가장 많이 검출되었다. 15종의 HCAs 중 ${beta}$-carbolines에 속하는 Norharman과 Harman이주로 검출되었으며 그 밖에 PhIP, Trp-P-1. Trp-P-2 등의 발암가능성이 있는 물질들이 검출되었다. 조리방법 측면에서 보면 간장을 이용한 조림방법보다는 직접적인 가열을 통한 구이방법이 많은 양의 HCAs를 형성시켰으며 구이 중에서도 muscle만 있는 부위에서의 검출함량보다는 muscle과 skin이 함께 있는 부위에서 검출함량이 더 많았다. 가열 조리한 어패류 분석방법에 대한 유효성을 확인해 본 결과 정량한계는 0.8-23.9 ng/mL, 검출한계는 0.2-7.2 ng/mL이었으며 회수율은 15.7-74.7%이었다.