• Analytical Science and Technology
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• v.20 no.5
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• pp.400-405
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• 2007

The comparative analysis of glycerin in cosmetic samples was carried out by LC/MS and $^1H$ NMR spectrometry. For the LC/MS analysis, aqueous solution was controlled in strong basic condition with sodium hydroxide, and benzoyl chloride was added to the solution for the derivatization of glycerin. The derivative was extracted using pentane and analyzed by the LC/MS. For the $^1H$ NMR analysis, sample was directly dissolved in $D_2O$ solvent without pretreatment. The quantitative analysis of glycerin was done by $^1H$ NMR ERETIC method. The analysis results of LC/MS and $^1H$ NMR showed that the calibration curves were a good linearity with $r^2=0.9991$ in the range of 0.1 to $10{\mu}g/mL$ and $r^2=1$ in the range of 25 to $500{\mu}g/mL$, respectively.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.2
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• pp.26-33
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• 2018

Xanthium sibiricum is used as a traditional folk medicine for the treatment of cancer, fever, headache, nasal sinusitis, and skin pruritus. This study aimed to identify components from Xanthium sibiricum extracts using an SPE-800MHz NMR-MS hyphenated system. The simultaneous acquisition of MS and NMR spectra from the same chromatographic peaks significantly increases the depth of information acquired for the compound and allows the elucidation of structures that would not be possible using MS or NMR data alone. LC -NMR analysis was conducted using a HPLC separation system coupled to 800 MHz spectrometer equipped with a cryoprobe, and a SPE unit was used to automatically trap chromatographic peaks using a HPLC pump. LC-MS analysis was conducted with a Q-TOF MS instrument using ESI ionization in the negative ion mode. Using the hyphenated analysis, several secondary metabolites were identified, such as 3',5'-O-dicaffeoylquinic acid, 1',5'-O-dicaffeoyl- quinic acid, and ethyl caffeate. These results demonstrate that the SPE-800MHz NMR-MS hyphenated system can be used to identify metabolites within natural products that have complex mixtures.

• Analytical Science and Technology
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• v.23 no.1
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• pp.97-101
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• 2010

(R)-N-3,5-dinitrobenzoyl (DNB) phenylglycinol derived chiral selector was used as a HPLC chiral stationary phase (CSP) for the resolution of racemic N-acylnaphthylalkylamines. In this study, determination of optical purity was performed by both chiral chromatography and NMR spectroscopy by using the (R)-phenylglycinol derived chiral selector. The data of accuracy and precision of each optical purity value are calculated from the results of NMR and HPLC experiments by comparing with true value. Average error of the NMR method was +2.2% with average RSD of 4.54%, while that of HPLC method was -3.5% with average RSD of 3.23%.

• Journal of Ginseng Research
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• v.22 no.2
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• pp.96-101
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• 1998

This paper describes the determination of bulk density and the discrimination of internal structure of red ginseng by nuclear magnetic resonance (NMR). The 102 red ginseng roots were tested for bulk density. The NMR properties measured by NMR parameters such as spin-lattice relaxation time ($T_1$) and spin-spin relaxation time ($T_2$) were determined using the low field proton NMR analyzer. Bulk density of red ginseng root showed a highly negative significant correlation (r=-0.8934) with the value of $T_1$, but a highly positive significant correlation (r=0.7672 and 0.5909) with the value of T21 (short T2) and T22 (long T2), respectively. Multiple regression equation, Y=-0.0069.$T_1$+0.3044.$T_{21}$-0.0156.$T_{22}$-0.6368, using the MNR parameter values of 80 red ginseng roots can effectively predict the bulk density of 22 red ginseng roots with the correlation coefficient of 0.9396 and the standard error of 0.086. The differences in the internal structure of normal and inside white part of red ginseng were easily found by the signal intensity of NMR image based on magnetic properties of proton nucleus.

• Bulletin of the Korean Chemical Society
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• v.5 no.2
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• pp.55-60
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• 1984

The NMR shift arising from the electron angular momentum and electron spin dipolar-nuclear spin angular momentum interactions has been investigated for a $4d^1$system in a strong crystal field environment of tetragonal symmetry. A general formula for NMR shift is used to compute the NMR shifts along the (100), (010), (001), (110) and (111) axes. We find that from the computed results, the NMR shift along the (100) and (010) axes is consistent with each other in a strong crystal field environment of tetragonal symmetry, but the NMR shift along the (001) axis is about triply greater in magnitude than those along the (100) and (010) axes and is opposite in sign to those along (100) and (010) axes. In this work, we express the expansion coefficients $a_1^{(i)}$ and $b_1^{(i)}$ of $A_i$ and $B_i$ in terms of $g_m^{(i)}$ and $h_m^{(i)}$ and two matrices $c_{lm}$ and $d_{lm}$ of radial dependence. The NMR shift is also separated into the contributions of multipolar terms. We find that $1/R^3$ term contributes dominantly to the NMR shift along the (100), (010), (001) and (110) axes while along the (111) axis $1/R^5$ term dominantly contributes. However, the contribtions of the other terms may not be negligible.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.435-442
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• 2008

Natural, synthetic, and treated diamonds were studied by NMR and EPR. It was demonstrated that natural and synthetic diamonds, treated and non-treated diamonds, high pressure high temperature (HPHT) treated and electron beam treated diamonds could be distinguished among each other based on the $^{13}C$ NMR spectra acquired for relatively short periods of 100 minutes. The $^{13}C$ NMR linewidths of gem quality synthetic diamonds were broader than 1.6 ppm due to the paramagentic effects of transition metals, generally used as catalysts, while the linewidths of gem quality natural diamonds were narrower than 0.5 ppm regardless of the methods of treatment. The linewidth (0.5 ppm) for a HPHT treated, gem quality natural diamond was as broad as more than twice of the linewidth (0.2 ppm) of an electron beam treated diamond. The $^{13}C$ NMR signal intensities of treated, gem quality natural diamonds were as strong as more than 10 times of the intensities of non-treated, gem quality natural diamonds. When correlated with the concentrations of the paramagnetic defects (electrons) obtained from the EPR spectra, the relative $^{13}C$ NMR signal intensities increased in proportion to the concentrations of the paramagnetic electrons contained in each sample but the electron beam treated diamond was an exception. This suggested that the lattice component, in addition to the paramagnetic defect component, should also be considered in determining the $^{13}C$ NMR signal intensity of the electron beam treated diamond.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.653-659
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• 2003

A 20 MHz pulsed NMR systems was employed to discriminate the geographical origin of soybeans and black beans (yak-kong) from Korea and foreign countries. Crude fat contents measured by soxhlet method were significantly (p<0.05) different between domestic and imported soybeans. Moisture and crude protein contents, measured by AOAC, were significantly different between domestic and imported black beans. In soybeans, values by solid fat content method and Carr-Purcell-Meiboom-Gill (CPMG) method using 20 MHz pulsed NMR showed the significant difference among soybeans from various the geographical origins. In black beans (yak-kong), NMR values measured by NMR except $T_1$ SR pulse sequence revealed the significant difference by the geographical origins. The habitat of soybeans and black beans could be identified by canonical discriminant analysis of chemical composition with $70{\sim}91.7\;%$ accuracy. Low field NMR data followed by discriminant analysis, however, granted the 100% of accuracy for classification of soybeans.

• Analytical Science and Technology
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• v.17 no.2
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• pp.98-107
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• 2004

In this study, $^1H$ NMR spectroscopy and HPLC were used to identify the type and quantity of each component in an acrylic coating materials applied for an automotive part. By the $^1H$ NMR analysis, it was found that this acrylic coating contained about 88.40 wt% of poly methyl methacrylate (PMMA), 7.05 wt% of methyl methacrylate (MMA), and 2.36 wt% of allyl methacrylate. Polymer additives such as a benzotriazole light stabilizer (Hisorb 328), an oxanilide light stabilizer, butylated hydroxy toluene (BHT), and dimethyl phthalate (DMP) were also identified and measured quantitatively from the $^1H$ NMR spectra. However, only two light stabilizers were identified by reverse phase (RP) HPLC analysis using Bondapak C18 column, methanol mobile phase, and a PDA (Photodiode array) detector. The contents of two light stabilizers in the acrylic coating were measured by a quantitative analysis through UV-Vis spectroscopy and compared with the NMR data. The analytical informations from $^1H$ NMR spetra were better than those from HPLC-PDA plot.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.386-388
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• 2006

Membrane proteins in highly oriented lipid bilayer samples are useful for membrane protein structure determination. We used in the past planar lipid bilayers which were aligned and supported on the glass slide. These samples were mechanically aligned in a magnetic field. However, these stacks of glass slides with planar lipid bilayers are not well suited for use with a commercial solid-state NMR probe with a round coil. Therefore, a homebuilt solid-state NMR probe was built and used with a stack of thin glass plates wherein the RF coil was wrapped directly around the flat square sample. Recently, we began to use magnetically aligned bicelles that are suitable for the structure determination of membrane proteins by solid-state NMR spectroscopy without any effort to build a flat square coil probe. These bicelle samples are well suited for use with a commercial solidstate NMR probe with a round coil, are very easy to prepare and are very stable, so that they can be kept for more than a year. In this paper, we present the solid-state NMR spectra of optimized and magnetically oriented bicelle samples of membrane proteins.

• Journal of the Korean Magnetic Resonance Society
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• v.22 no.2
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• pp.34-39
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• 2018

The Nuclear Magnetic Resonance (NMR) technique using Dynamic Nuclear Polarization (DNP) procedures is one of the promising techniques that enable overcoming low sensitivity problems in NMR spectroscopy. We constructed an ODNP-NMR system using a commercial benchtop EPR spectrometer. The $^1H$ NMR peak area of water in aqueous solutions of 4-hydroxy-TEMPO was enhanced more than 95 times in the ODNP-NMR experiments. Our signal enhancement results were about 55% of the previously reported result. This could be due to non-uniform microwave power over a sample and unwanted sample heating by microwave. However, this portable ODNP-NMR spectrometer will be eventually useful for site-specific detection with nano-scale spatial resolutions and molecular dynamics studies with significantly improved signal sensitivity.