• Journal of Plant Biology
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• v.36 no.3
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• pp.297-300
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• 1993

Six flavonoid compounds from the ethyl acetate fraction of Machilus thunbergii leaves were identified by HPLC. Separation by reversed phase chromatography on u-Bondapak C18 column was achieved by isocratic elution. The contents of the major flavonoids, guaijaverin and quercitrin were about 0.48% (w/w) and 0.98% (w/w) for the methanol extract, respectively.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.1070-1072
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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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.

• Analytical Science and Technology
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• v.5 no.3
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• pp.333-338
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• 1992

The tea tannins, epigallocatechin, epigallocatechin gallate, were successfully separated by a Sephadex LH-20 column by the acetone based gradient elution. Each fractions was collected by monitoring at 280nm. Purified fractions were directly characterized by fast atom bombardment mass spectrometry. Epigallocatechin and epigallocatechin gallate were identified and shown as low as 70% purity in the reversed phase column. This revised method is more advantageous than known methods in purity and rapidity.

• Bulletin of the Korean Chemical Society
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• v.18 no.10
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• pp.1085-1089
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• 1997

A new HPLC chiral stationary phase (CSP 3) has been prepared by connecting N-phenyl N-propyl amide of (S)-naproxen to silica gel through the 6-methoxy-2-naphthyl group of (S)-naproxen. The new CSP has been applied in resolving a homologous series of N-(3,5-dinitrobenzoyl)-α-amino acid esters and a homologous series of N-(3,5-dinitrobenzoyl)-α-(4-alkylphenyl)alkylamines. The separation factors, α, for resolving a homologous series of N-(3,5-dinitrobenzoyl)-α-amino esters and a homologous series of N-(3,5-dinitrobenzoyl)-α-(4-alkylphenyl)alkylamines on the new CSP have been found to remain almost constant throughout the wide range of the length of the alkyl substituent of the analytes while those on the previously reported CSPs (CSP 1 and 2) which were prepared by connecting N-phenyl N-propyl amide of (S)-naproxen to silica gel through the N-propyl group increase or decrease continuously. These results are concluded to support the chiral recognition models which utilize the intercalation of the alkyl substituent of the racemic analytes between the adjacent strands of CSP 1 or 2 to rationalize the increasing or decreasing trends of separation factors.

• Analytical Science and Technology
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• v.36 no.4
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• pp.143-151
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• 2023

Considering the greater role of α-amino acids in our daily lives, the enantiomer resolution of seven α-amino acids derivatized with fluorogenic reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, NBD-F) by chiral HPLC on amylose or cellulose trisphenylcarbamate derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence (FL) detection was performed. The degree of enantioseparation and resolution was affected by nature and selector backbones of the CSPs as well as the kind of amino acids. Baseline enantiomer separation and resolutions were observed for the enantiomers of all analytes as NBD derivatives especially on coated type amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-H and Lux Amylose-1). The other CSPs also showed good enantioselectivity except for the CSPs (Chiralpak IB, Chiralcel OD-H and Lux Cellulose-1) having cellulose tris(3,5-dimethylphenylcarbamate) as chiral selectors. The developed analytical chiral method was applied to determine the enantiomeric purity of seven commercially available L-α-amino acids and the impurities as D-forms were found to be in the range 0.08-0.87 %, respectively. The intra- and interday accuracy and precision assays showed high accuracy and precision of the developed analytical method. This chiral HPLC method for the enantiomer resolution of amino acids using fluorescent derivatization could be useful for the determination of enantiomeric purity of pharmaceuticals and biological study for amino acid type compounds among chiral drugs.

• The Korea Journal of Herbology
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• v.22 no.2
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• pp.97-102
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• 2007

Objectives : This study presents a high performance liquid chromatography - electrospray ionization-mass spectrometer (HPLC-MS/MS) methods for the quantitative and qualitative analysis of various active components in Samul-tang, which is composed of four crude herbs. Methods : HPLC-ESI-MS/MS for the determinations of paeoniflorin and 5-HMF (5-hydroxymethyl 2-furaldehyde) in the Samul-tang, the separation method was performed on an COSMOS1L 5C18-AR-Il (2.0 X 150 mm I.D.) column by gradient elution with 0.1% acetic acid and 5% CH3CN in water (A)-0.1% acetic acid and 5% H20 in CH3CN (B) as the mobile phase at a flow-rate of 300 ${\mu}L/min$ with detection at quadrupole mass spectrometer. The all marker substances were always detected as the base peaks in the positive ion mode. Results : The paeoniflorin of Paeoniae Radix in Samul-tang showed a strong base peak [M+H2O]+ in the positive detection mode to give the following as; paeoniflorin (498.109 [M+H2O]+, 479.8 [M]+, 301 [M-glucose]+, 179.3 [glucose]+). Based on the HPLC retnetion time and MS of standard compounds confirmed the identity of active compounds in Rehmanniae Radix Preparata as follows; 5-HMF (127.0[M+H]+, 109.3 [M-OH]+) in the positive ion mode. Conclusion : According to the above results, HPLC-ESI-MS method permits assignment of tentative structures such as paeoniflorin and 5-HMF in the Samul-tang.

• Journal of Dairy Science and Biotechnology
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• v.15 no.1
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• pp.1-9
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• 1997

This study was conducted to efficiently separate the Ig from Korean native cattle colostrum and to utilize them as an immunogen for the production of antibodies aginst rabbit. The results obtained were as follows : 1. About 84% of Ig G could be separated from Korean native cattle colostrum by·gel filtration using Superose 12 column on HPLC. The separation profile of Korean native cattle colostral immunoglobulin was similar that of Holstein colostral Ig. 2. Separation of Korean native cattle colostral Ig by anion exchange chromatography using Mono Q column on HPLC was poor resolution chromatographic pattern. 3. Hi-Trap Protein G column showed better results than the Protein A Sepharose CL-4B column in the Ig G binding capacity from Korean native cattle colostral Ig. 4. Protein G Sepharose Fast Flow system resulted in higher Ig g binding capacity as the industrial size scale-up approach. 5. Sufficient titer reaction of antibody to Korean native cattle colostral Ig G was confirmed by ELISA.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.547-552
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• 2003

Separation and determinations of Co(II) and Ni(II) ions as their 4-(2-pyridylazo)resorcinol(PAR) chelates by reversed-phase capillary high-performance liquid chromatography(RP-CpHPLC) were performed. Among many capillary columns, Vydac C4 column was selected and acetonitrile solution was used as mobile phase. The effect of pH and MeCN concentration(%) on the retention factor, k and peak intensity was examined and discussed. As a results, it was found that 22.5% MeCN and pH 5.60 was adequate as mobile phase for the separation of the two metal ions and determination of Co(II) ion, but the mobile phase condition for Ni(II) ion determination was 22.5% MeCN of pH 7.20. Detection limit(D.L., S/N=3) of Co(II) and Ni(II) ions were $2.0{\times}10{-7}$ M(14.9 ppb) and $1.0{\times}10{-6}$ M(59.2 ppb), respectively.

• Analytical Science and Technology
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• v.26 no.3
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• pp.182-189
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• 2013

The purpose of this research is to separate and quantitate selenium species in some food samples with HPLC-ICP-MS. Cation exchange chromatography showed efficient separation only for inorganic Se species while reversed phase ion pair chromatography showed good separation for both inorganic and organic Se species. $C_8$ column ($Symmetryshield^{TM}\;RP_8$, 3.5 ${\mu}m$, $4.6{\times}150$ mm) was used with optimum condition of 5% methanol mobile phase, 0.05% of nonafluorovaleric acid ion pairing reagent. Five standard Se species of Se(IV), Se(VI), SeCys(selenocystein), SeMet(selenomethionine) and Se-M-C(seleno methyl cystein) were separated successfully under the optimum condition (mobile phase; 5% methanol, ion-pairing reagent; 0.05% nonafluorovaleric acid, flow rate; 0.9 mL $min^{-1}$). To extract Se species, microwave assisted and enzyme-assisted extraction methods were studied. In enzyme-assisted extraction method, protease I for garlic, protease I plus trypsin for pork and mackerel, and protease XIV for tuna showed the best extraction efficiency. With the optimum condition for each sample, it was found that mostly inorganic Se, SeCys and SeMet are present in the sample studied ranging from few ${\mu}g$ $g^{-1}$ to few tens of ${\mu}g$ $g^{-1}$.