• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.520-526
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• 1991

Retention behavior of lanthanides was studied on the dynamic system using dinonylnaphthalene sulfonic acid cation exchanger and tartaric acid as a complexing agent. The relations between logk' and log$[NH^{4+}]$/log[tartarate], and between logk' and logR showed good linearity in isocratic and gradient elution, respectively. In gradient elution of tartaric acid the slopes were increased as the initial concentrations were decreased. Column efficiencies and resolution of lanthanides on dinonylnaphthalene sulfonic acid equilibrated cation exchanger were found to be better in ${\alpha}$-hydroxyisobutyric acid eluent than in tartaric acid.

• KSBB Journal
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• v.22 no.2
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• pp.119-122
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• 2007

Since egg white contains various protein, it is important to research the protein distribution of egg white. Specially, lysozyme and ovalbumin important proteins, are used in medicine and food industry. Reversed phase high performance liquid chromatography has been used for separation of egg white, and column of RP-HPLC is available in variety. We have used C4, C8 and C18 columns to obtain chromatograms by varying carbon chain length of stationary phase. Long carbon chain length of stationary phase has good separation of egg white. Also, we have changed the composition of mobile phase (acetonitrile, water, and trifluoroacetic acid) to find optimum chromatograms. Acetonitrile and water composition of 50 : 50 show many peaks from egg white. Isocartic and gradient elution in RP-HPLC were used to compare the chromatography of egg white.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.582-592
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• 1990

Retention behavior of lanthanide-$\alpha$HiBA complexes was studied on the cation exchanger (LC-18 coated with $C_{20}H_{41}SO_4^-$). An equation predicting retention of lanthanides in isocratic or gradient elution with sodium ion and $\alpha$-HiBA concentration was derived from ion exchange equilibria of metal-ligand complex system, respectively. The relations between log k' and log [Na$^+$] /log [$\alpha$-HiBA) showed non-linearity in isocratic elution. In gradient elution a good linearity between log k' vs log R was obtained. The values of slopes (log k / log R) gave good agreements between calculation and experiment. Individual capacity factors ($k'_{Ln}^{3+}, k'_{LnL}^{2+}, k'{LnL2+}) and stability constant (${\beta}_1$, ${\beta}_2$, ${\beta}_3$) of lanthanide-$\alpha$HiBA complexes were calculated by the non-linear least square fittings using the retention equation. The correlation coefficients of lanthanides were shown better than 0.9996 between experiment and calculation.

• YAKHAK HOEJI
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• v.55 no.4
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• pp.277-283
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• 2011

Simultaneous monitoring of catecholamines and serotonin with their appropriate extraction from the biological samples is required in order to understand thoroughly the regulation of the central and peripheral nervous system. In the present research the segmented gradient elution with the solid phase extraction using a C18 cartridge rather than the previous isocratic elution with alumina extraction is successfully employed to determine norepinephrine (NE), epinephrine (E), dopamine (DA), serotonin (5HT), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5HIAA) simultaneously within 20 minutes using 3,4-dihydroxyhydrocinnamic aicd as the internal standard (IS). Linearities were obtained in the concentration range between $5{\times}10^{-6}M$ and $1{\times}10^{-4}M$ for all 7 compounds with detection limits of 0.6~1.9 ${\mu}M$. The present HPLC/ECD method yielded reasonable accuracy (relative error; -1.4~1.1%) and precision (relative standard deviation; 0.4~1.9%) for 9 measurements of the standard solution consisting of NE, E, DA, 5HT, DOPAC and 5HIAA compounds. Recoveries of catecholamines, serotonin and their metabolites from human serum were in the range of 57%~86%. While the concentrations of NE and 5HT in the serum of normal Sprague-Dawley rat were found as $1.4{\times}10^{-6}M$ and $2.6{\times}10^{-6}M$, respectively, the contents of NE and 5HT in the serum of the stressed rat were increased 5.6 times and 1.4 times more, respectively.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.829-834
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• 2011

Lysozyme in egg white functions as bacteriolysis agent and ovalbumin plays a role as antigen in immune system. Egg white analysis methods usually include electrophoresis, gel permeation chromatography and reversed-phase HPLC(RP-HPLC). Among them, RP-HPLC was selected for rapid analysis and C18 column(Agilent, USA) was used as HPLC column. Optimum conditions were searched by changing mobile phase and temperature. Capacity factor and resolution were calculated and compared for various elution conditions. In the isocratic elution, mobile phase volume ratio was changed from 30/70/0.1 to 60/40/0.1(Acetonitrile(ACN)/Distilled water(DW)/Trifluoroacetic acid(TFA)). ACN composition was increased by 10% and temperature was set as $20^{\circ}C$. In the gradient elution, ACN/DW ratio was changed from 10/90 to 60/40 during 20 minute and temperature was varied as 20, 30 and $40^{\circ}C$. In the isocratic elution, three peaks were separated at 50/50/0.1. Lysozyme and ovalbumin were confirmed as first and third peak in three peaks respectively. In the gradient elution, four peaks were separated at $30^{\circ}C$. Lysozyme and ovalbumin were confirmed as first peak and third peak in four peaks respectively.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.259-264
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• 1993

Ion chromatographic method has been applied for burnup measurement of irradiated nuclear fuel by dynamic system using 1-octanesulfonate as a cation exchanger and $\alpha$-hydroxyisobutyric acid as an eluant. A number of elution techniques were evaluated for the optimum separation of plutonium, uranium and neodymium. These elements were individually separated and collected by gradient elution between 0.05 M and 0.40 M of $\alpha$-hydroxyisobutyric acid in a single column, and finally determined by isotope dilution mass spectrometry. The burnup data from this method were compared with those from conventional anion exchange method. The results showed a good agreement within 3.5 % of difference between two methods.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.4
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• pp.209-213
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• 1998

The sesaminol glucosides in 80% EtOH extract from sesame seeds were separated by high performance liquid chromatography (HPLC). A HPLC system using a Develosil ODS-5 column and gradient elution system from 30% to 80% methanol was selected for separation and quantitative determination of sesaminol triglucoside, sesaminol diglucoside, and sesaminol monoglucoside. Quantitative analyses for these sesaminol glucosides, sesaminol triglucoside, sesaminol diglucoside, and sesaminol monoglucoside were determined on the basis of standard curve of sesaminol glucosides. Sesaminol triglucoside, sesaminol diglucoside and sesaminol monoglucoside contents of the seed of one Korean sesame cultivar, Danbaekggae, were 56.4 mg/100g, 9.6 mg/100g, and 7.5 mg/100g, respectively. The most abundant aglycon of lignan glucosides in sesame seed was sesaminol triglucoside

• KSBB Journal
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• v.15 no.6
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• pp.605-608
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• 2000

Oligodeoxynucleotides (ODNs) were separated by high-performance membrane chromatography (HPMC), a combined system of chromatography and membrane. The separation mechanism involved anion-exchange, and the stationary phase was cation CIM (Convective Interaction Media) DEAE disk (16${\times}$3 mm). Two types of mobile phase were used, buffer A (20mM Tris-HCl, pH 7.4) and buffer B (buffer A + 1M NaCl). As the amount of NaCl dissolved in buffer linearly increased, the retention time shortened, which enabled a gradient elution mode. Based on the number of theoretical plates and resolution observed, the optimum mobile phase and operating condition (Buffer A/Buffer B=50/50 - 20/80 vol%, gradient time 2 min) were experimentally determined. In this experimental condition, ODNs were separated within 2 min at a mobile phase flow rate of 6 ml/min.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.181-186
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• 2005

This experiment was conducted to know the appropriate methods for extraction and determination of rutin contained buckwheat plants. The efficient HPLC analytical condition of rutin contained buckwheat plants was developed. The gradient elution employed a $250mm\times4.6mm$ i.d. Tosoh ODS 120T column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of $2\%$ Acetic $acid-45\%$ Acetonitrile, and mobile phase B, comprising $2\%$ aqueous acetic acid, and delivered at a flow rate of 1mL/min as follows: 0-18 min, $50-100\%$ A; 18-20 min, $100-50\%$ A; 20-22 min, $50\%$ A. The UV detection wavelength was set at 355 nm. The limit of detection (LOD) for rutin standard compound was 20 ng/mL. And, the higher content of rutin in the extracts was obtained by $80^{\circ}C$ reflex extraction for 120 min. from plants of buckwheat using ethanol.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.224-232
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• 2008

The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. The contents of catechins and caffeine in green tea are considered as a standard of quality evaluation of green tea. Therefor, the purpose of this study was to investigate the most suitable HPLC condition for simultaneous determination of catechins and caffeine in green tea extracts. The efficient HPLC analytical condition of catechins and caffeine contained green tea extracts was developed. The gradient elution employed a $250\;mm\;{\times}\;4.6\;mm$ i.d. YMC-pak ODS-AM 303 column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of 0.1% aqueous phosphoric acid, and mobile phase B, comprising 100% MeOH, and delivered at a flow rate of 1 mL/min as follows: $0{\sim}25\;min$, 80% A; $26{\sim}50\;min$, $80{\sim}70%$ A; 51 min, 80% A. $51{\sim}55\;min$, 80% A. The UV detection wavelength was set at 280 nm. The limit of detection (LOD) for catechins and caffeine standards were under 50 ng/mL.