• 한국축산식품학회지
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• 제39권1호
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• pp.1-12
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• 2019

The objective of this study was to establish an optimized 1D $^1H$ quantitative nuclear magnetic resonance (qNMR) analytical method for analyzing polar metabolites in meat. Three extraction solutions [0.6 M perchloric acid, 10 mM phosphate buffer, water/methanol (1:1)], three reconstitution buffers [20 mM 3-morpholinopropane-1-sulfonic acid, 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid, phosphate buffer], and two pulse programs (zg30, noesypr1d) were evaluated. Extraction with 0.6 M perchloric acid and 20 mM phosphate resulted in a stable baseline and no additional overlap for quantifying polar metabolites in chicken breast. In qNMR analysis, zg30 pulse program (without water-suppression) showed smaller relative standard deviation (RSD) and faster running time than noesypr1d (water-suppression). High-performance liquid chromatography was compared with qNMR analyses to validate accuracy. The zg30 pulse program showed good accuracy and lower RSD. The optimized qNMR method was able to apply for beef and pork samples. Thus, an optimized 1D $^1H$ qNMR method for meat metabolomics was established.

• 한국광물학회지
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• 제21권3호
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• pp.321-329
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• 2008

비정질 규산염 나노입자는 지각에 풍부한 규소와 산소로 이루어진 비다공성 나노입자로서 광물학을 포함한 지구환경과학과 산업적 측면에서 모두 중요한 물질이다. 본 연구에서는 $^{1}H$과 $^{29}Si$ MAS NMR분광분석을 통해 7 nm와 14 nm 규산염 나노입자의 규소와 수소 원자 환경을 측정하고, 입자 크기에 따른 규산염 나노입자 원자 환경 변화를 규명하였다. NMR 스펙트럼의 화학적 이동 값의 이론적 배경을 이해하기 위해 양자화학계간을 통해 $Si_{3}O_{6}H_6,\;Si_{4}O_{5}H_{10},\;Si_{5}O_{4}H_{12}$ 분자계간모델의 화학 차폐를 계산하였다. $^{29}Si$ MAS NMR의 결과, 이중 실라놀(geminal silanol)과 단일 실라놀(single silanol), 실록산(siloxane) 구조의 Si 원자 환경에 해당하는 $Q^2,\;Q^3,\;O^4$가 구분되어 나타나며 입자 크기에 따라 $Q^2,\;Q^3,\;O^4$가 7 nm규산염 나노입자에는 $7{\pm}1%,\;27{\pm}2%,\;66{\pm}2%$, 14 nm 규산염 나노입자에는 $6{\pm}1%,\;21{\pm}2%,\;73{\pm}2%$의 분포를 갖는다. $Q^2,\;Q^3$ 구조는 나노 입자의 표면적에 대부분 존재하는 것으로 예상되었으나, 두 규산염 나노입자의 표면적 차이에 비해 $Q^2,\;Q^3$ 양의 차이가 적으며, 이는 입자 표면 뿐 아니라 입자 내부에도 $Q^2,\;Q^3$ 구조가 존재함을 의미한다. $^{1}H$ MAS NMR 스펙트럼은 물리흡착 된 물(physisorbed water), 수소결합 된 수산기(hydrogen bended silanol), 비 수소결합 된 수산기(non-hydrogen bonded silanol)를 구분하여 나타낸다. 14 nm 비정질 규산염 나노입자에 비해 7nm 나노입자에 약 3.4 배의 수소 원자가 존재하며, 더 강한 수소결합 세기를 갖는다. 전체 수산기 중에서 비 수소결합 된 수산기가 차지하는 비율이 7 nm 규산염 나노입자 보다 14 nm 규산염 나노입자에서 더 높으며, 이는 수소 원자간의 상대적 거리(proximity)가 14 nm 임자에서 더 긴 것을 지시한다. 본 연구결과를 통하여 현재까지 알려지지 않은 규산염 나노입자의 입자의기에 의한 다양한 원자 구조의 변화를 규명하였다.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3644-3649
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• 2011

Multinuclear solid-state nuclear magnetic resonance (NMR) experiments were performed to investigate the local structure changes of nanoporous silica during hydrothermal treatment and surface modification with 3-aminopropyltriethoxysilane (3-APTES). The nanoporous silica was prepared by sol-gel polymerization using inexpensive sodium silicate as a silica precursor. Using $^1H$ magic angle spinning (MAS) NMR spectra, the hydroxyl groups, which play an important role in surface reactions, were probed. Various silicon sites such as $Q^2$, $Q^3$, $Q^4$, $T^2$, and $T^3$ were identified with $^{29}Si$ cross polarization (CP) MAS NMR spectra and quantified with $^{29}Si$ MAS NMR spectra. The results indicated that about 25% of the silica surface was modified. $^1H$ and $^{29}Si$ NMR data proved that the hydrothermal treatment induced dehydration and dehyroxylation. The $^{13}C$ CP MAS and $^1H$ MAS NMR spectra of 3-APTES attached on the surface of nanoporous silica revealed that the amines of the 3-aminopropyl groups were in the chemical state of ${NH_3}^+$ rather than $NH_2$.

• 한국자기공명학회논문지
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• 제17권1호
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• pp.40-46
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• 2013

For a case study of suspected paraquat intoxication, we developed a simple and rapid method of $^1H$ qNMR to determine the mili-molar amount of paraquat in postmortem blood samples. There were no interfering signals from endogenous compounds in the chemical shift of paraquat and diquat (internal standard). The amount of sample used ranged from 0.25 mM to 10.0 mM. Diquat, which has similar physicochemical properties with paraquat, was chosen as an internal standard. The NMR experimental conditions, relaxation delay time and CPMG spin-echo pulse sequence were optimized. The developed method was validated in terms of specificity, accuracy, precision, matrix effect, recovery, limit of detection (LOD), and low limit of quantification (LLOQ). The proposed qNMR method provided a simple and rapid assay for the identification and quantification of the quaternary ammonium herbicide, "paraquat" in postmortem blood samples. This method was tested by using the blood from the heart of a man who was intoxicated with paraquat. In this particular case, the level of paraquat was 1.07 mM in the blood. For the determination of quaternary ammonium herbicides, qNMR could also be used to provide a better understanding of the currently available techniques.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.662-667
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• 2023

Allantoin is an abundant component of yams and has been known as a skin protectant due to its pharmacological activities. In previous methods for allantoin determination using high-performance liquid chromatography (HPLC), the separation was unsatisfactory. We herein developed a ¹H quantitative nuclear magnetic resonance (qNMR) method for quantification of allantoin in the flesh and peel of yams. The method was carried out based on the relative ratio of signals integration of allantoin to a certain amount of the internal standard dimethyl sulfone (DMSO₂) and validated in terms of specificity, linearity (range 62.5-2000 ㎍/ml), sensitivity (limit of detection (LOD) and quantification (LOQ) 4.63 and 14.03 ㎍/ml, respectively), precision (RSD% 0.02-0.26), and recovery (86.35-92.11%). The method was then applied for the evaluation of allantoin in flesh and peel extracts of four different yams cultivated in Korea.

• 한국축산식품학회지
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• 제41권2호
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• pp.312-323
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• 2021

The purpose of this study was to use 1H nuclear magnetic resonance (1H NMR) to quantify taste-active and bioactive compounds in chicken breasts and thighs from Korean native chicken (KNC) [newly developed KNCs (KNC-A, -C, and -D) and commercial KNC-H] and white-semi broiler (WSB) used in Samgye. Further, each breed was differentiated using multivariate analyses, including a machine learning algorithm designed to use metabolic information from each type of chicken obtained using 1H-13C heteronuclear single quantum coherence (2D NMR). Breast meat from KNC-D chickens were superior to those of conventional KNC-H and WSB chickens in terms of both taste-active and bioactive compounds. In the multivariate analysis, meat portions (breast and thigh) and chicken breeds (KNCs and WSB) could be clearly distinguished based on the outcomes of the principal component analysis and partial least square-discriminant analysis (R2=0.945; Q2=0.901). Based on this, we determined the receiver operating characteristic (ROC) curve for each of these components. AUC analysis identified 10 features which could be consistently applied to distinguish between all KNCs and WSB chickens in both breast (0.988) and thigh (1.000) meat without error. Here, both 1H NMR and 2D NMR could successfully quantify various target metabolites which could be used to distinguish between different chicken breeds based on their metabolic profile.

• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.519-524
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• 1998

In this work, we applied the 1D 11B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO2-B2O3). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D 11B nutation NMR experiment. The 11B NMR parameters, quadrupole coupling constants (e2qQ/h) and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

• 한국자기공명학회논문지
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• 제1권2호
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• pp.95-102
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• 1997

Deuterium quadrupole coupling constant (e2qzzQ/h) of ($\mu$3-C2H)[Co(CO)3]3 was determined by using solid-state deuterium MAS NMR spectroscopy. The small quadrupole coupling constant of bridging methyne unit relative to sp-acethylene in propyne is discussed in terms of the C-H bond length and the negative charge on the carbon.

• Journal of the Korean Wood Science and Technology
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• 제35권6호
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• pp.145-151
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• 2007

산겨릅나무 수피의 성분 연구를 위해 수피를 채취하여 70% 아세톤 용액으로 추출하고 농축한 후 분획깔때기로 헥산, 디클로로메탄, 에틸아세테이트 및 수용성으로 순차 추출하여 동결건조하였다. 에틸아세테이트용성 분획에 대하여 Sephadex LH-20 칼럼크로마토그래피를 반복적으로 수행하여 5개의 페놀성 화합물을 분리하였다. 화합물의 구조는 $^1H-NMR$, $^{13}C-NMR$, 2D-NMR 및 MS 스펙트럼을 분석하여, (+)-catechin (1), (-)-epicatechin (2), (-)-epicatechin-3-O-gallate (3), gallic acid (4) 및 6''-O-galloylsalidroside (5)으로 동정하였다. (-)-epicatechin-3-O-gallate (3), gallic acid (4), 6''-O-galloylsalidroside (5)는 산겨릅나무 수피에서 처음 분리되었다.

• Bulletin of the Korean Chemical Society
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• 제19권5호
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• pp.501-503
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• 1998

In this work, we applied the 1D $11^B$ nutation NMR method for the analysis of the local structural environments in powdered borosilicates $(SiO_2-B_2O_3)$. Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density ma trix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D $11^B$ nutation NMR experiment. The $11^B$ NMR parameters, quadrupole coupling constants $(e^2qQ/h)$ and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.