• FOCUS: LIFE SCIENCE
• /
• no.1
• /
• pp.6.1-6.9
• /
• 2024

The document is a white paper on Hydrophilic Interaction Liquid Chromatography (HILIC) analysis method development. HILIC is a type of chromatography that uses an organic/aqueous mobile phase and a polar stationary phase. In HILIC, water is a strong solvent, and unlike in Reversed Phase Liquid Chromatography (RPLC), increasing the proportion of water in the mobile phase reduces the retention time of the analyte. The paper discusses when to consider HILIC analysis methods, the advantages of HILIC, and the challenges often encountered due to the lack of understanding of HILIC mechanisms compared to RPLC. It also provides a systematic flowchart for intelligent solutions for HILIC analysis method development, which includes a three-step approach for chromatography analysis method development. The first step involves gathering as much information as possible about the analyte (e.g., pKa, log P, log D). The second step involves analyzing the sample under different pH conditions using three HILIC columns in either isocratic or gradient mode to identify the suitable column/pH combination for the analyte. The third step involves optimizing the separation by investigating other parameters such as temperature and ionic strength, and assessing the robustness of the method. The paper emphasizes that the selection of the appropriate stationary/mobile phase combination, based on the differences between the HILIC stationary phases and the mobile phase pH, can provide high selectivity in the analysis. This step-by-step approach can help users develop an efficient analysis method.

• Applied Biological Chemistry
• /
• v.37 no.6
• /
• pp.451-455
• /
• 1994

To detect naturally occurring bioactive compounds from unused marine resources, the screening for the 5-lipoxygenase(potato lipoxygenase-II) inhibitors in Asterina pectinifera, Halocynthia roretzi skin, Nototodarus sloani ink, Anthocidaris crassispina skin, Sargassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata was carried out. Water, ether, acetone and methanol fractions extracted from Sargassum horneri had strong inhibitory effect on enzymatic lipid oxidation by potato lipoxygenase-II, and their $IC_{50}$ were 320, 18, 9.5 and $100\;{\mu}g/mL$, respectively. The $IC_{50}$ of ether fraction extracted from Asterina pectinifera and acetone fraction extracted from Nototodarus sloani ink were 29.5 and $34.3\;{\mu}g/mL$, and these extracts showed relatively excellent inhibitory activity. Nonpolar solvent (ether, acetone) extracts of tested marine organisms had more inhibitory effect against 5-lipoxygenase than the polar solvent(water) extracts.

• Journal of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.55-63
• /
• 1987

The systematic investigation of the retention behaviors of 18 monosubstituted benzenes in reversed-phase liquid chromatography(RPLC) was studied in order to predict the separation possibility of their mixtures and study the contribution of substituent group to the retentions of solutes. The columns and mobile phases employed in this study were $\mu$ -Bondapak $C_{18}$, $\mu$-Bondapak phenyl columns and methanol/water, acetonitrile/water, and THF/water, respectively. The polar substituents such as phenol, aniline, acetophenone and benzonitrile have smaller capacity factor(k') values than benzene, while nonpolar ones such as alkylbenzenes and halobenzenes show larger k' value. The capacity factors of all solutes increased on both C18 bonded and phenyl bonded phases as the organic solvent content of three organic solvent-water mixtures decreased. The absolute differences in capacity factor(${\Delta}k$') between substituent and benzene were graphically shown for the prediction of the separation of the mixture and interpretation of the elution behavior of substituent. In addition, the selectivity of solvent system for the separation of the mixture was investigated in both two columns and three mobile phases.

• Polymer(Korea)
• /
• v.38 no.4
• /
• pp.535-543
• /
• 2014

This work, which was about the synthesis of naphthalimidopropyl acrylate and GMA copolymers and their physical properties, investigated the compositions of the copolymer, the reactivity ratios of the monomer, resonance effect (Q), polar effect (e) and fluorescence of naphthalene. Azobisisobutyronitronitryl (AIBN) as an initiator was employed at $60^{\circ}C$ with dimethylformamide (DMF) of solvent for the copolymerization of NIPA. $r_1$ was found to be higher than $r_2$ from the reactivity ratios of the monomer obtained from Fineman-Ross (F-R), Kelen-$T{\ddot{u}}d{\ddot{o}}s$(K-T) methods. NIPA was found to be more copolymerized than GMA. $r_1{\cdot}r_2$ product was lower than 1, copolymerization was maked random-alternating type. The fluorescence spectrum of these polymers showed a weak monomer fluorescence band at 380 nm and a strong excimer fluorescence band at about 460 nm. Fluorescence life time of NIPA monomer showed fluorescence cover with UV 355 nm at room temperature, and life time showed $5.1449{\times}10^{-7}s$.

• Restorative Dentistry and Endodontics
• /
• v.31 no.4
• /
• pp.290-299
• /
• 2006

Objectives: The purpose of this study is to evaluate the effect of ethylene glycol analogs on modulus of elasticity and ultimate tensile strength of moist, demineralized dentin matrix. Methods: Dentin disks 0.5 mrn thick were prepared from mid-coronal dentin of extracted. unerupted, human third molars. 'I' beam and hour-glass shaped specimens were prepared from the disks, the ends protected with nail varnish and the central regions completely demineralized in 0.5M EDTA for 5 days. Ultimate tensile stress (UTS) and low strain modulus of elasticity (E) were determined with specimens immersed for 60 min in distilled water $(H_{2}O)$, ethylene glycol $(HO-CH_{2}-CH_{2}-OH)$, 2-methoxyethanol $(H_{3}CO-CH_{2}-CH_{2}-OH)$, and 1,2-dimethoxyethane $(H_{3}CO-CH_{2}-CH_{3}-OCH_{3})$ prior to testing in those same media. Modulus of elasticity was measured on the same specimens in a repeated measures experimental design. The results were analyzed with a one-way ANOVA on ranks, followed by Dunn's test at ${\alpha}\;=\;0.05$. Regression analysis examined the relationship between UTS or E and hoy's solubility parameter for hydrogen bonding $({\delta}_{h})$ of each solvent. Results: The UTS of demineralized dentin in water, ethylene glycol, 2-methoxyethanol, and 1,2-dimethoxyethane was 24 (3), 30 (5), 37 (6), and 45 (6) MPa, ${\times}$ (SD) N = 10. Low strain E for the same media were 16 (13), 23 (14), 52 (24), and 62 (22) MPa. Regression analysis of UTS vs ${\delta}_{h}$ revealed a significant $(p\;<\;0.0001,\;r\;=\;-0.99,\;R^{2}\;=\;0.98)$ inverse, exponential relationship. A similar inverse relationship was obtained between low strain E vs ${\delta}_{h}\;(p\;<\;0.0005,\;r\;=\;-0.93,\;R^{2}\;=\;0.86)$. Significance: The tensile properties of demineralized dentin are dependent upon the hydrogen bonding ability of polar solvents $({\delta}_{h})$. Solvents with low ${\delta}_{h}$ values may permit new interpeptide H-bonding in collagen that increases its tensile properties. Solvents with high ${\delta}_{h}$ values prevent the development of these new interpeptide H-bonds.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.23 no.6
• /
• pp.959-963
• /
• 1994

To detect bioactive compounds present in unused marine resources, the screening for the 5-lipoxygenase inhitors in Asterina pectinifera, Halocynthia roretzi skin, Nototodarus sloani ink, Anthocidaris crassispina skin, SArgassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata was carried out. THe ether and acetone extracts of Sargassum horneri had the strongest antioxygnic activityon lipid oxidation by potato lipoxygenase-1 (one of 5-lipoygenase) among the tested marine samples and their $IC_{50}$ were 0.3 and 1.1g/ml, respectively. The ether and acetone extracts of Asterina pectinifera, the acetone extracts of Halocynthia roretizi, and the acetone extracts of Nototodarus sloani ink had strong inhibitory activity and their $IC_{50}$ were 72.5, 65, 13.3 and $13.3\mu\textrm{g}/ml$, respectively. In addition, the $IC_{50}$ of the acetone extracts of Agarum cribrosum and Desmarestia ligulata, and the ether extracts of Desmarestia ligulata were 15.5, 35 and $30.5\mu\textrm{g}/ml$, respectively. The nonpolar solvent (ether, acetone) extracts of tested marine organism had more antioxigenic effect against 5-lipoxygenase than the polar solvent(water) extracts.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.9
• /
• pp.989-996
• /
• 2007

In this study, abiotic transformation of 1-naphthol(1-NP) via oxidative-coupling reaction and its reaction products were investigated in the presence of Mn oxides. The reaction products were characterized for their relative polarity using solvent extraction experiment and reverse-phase HPLC, and for structure using CCMS and LC/MS, and for absorption characteristics using UV-Vis spectrometry. The reaction products present in aqueous phase were more polar than parent naphthol and comprised of 1,4-naphthoquinon(1,4-NPQ) and oligomers such as dimers and trimers. Hydrophilic component present in water phase after solvent$(CH_2Cl_2)$ extractions was identified as naphthol polymerized products having molecular weight(m/z) ranging from 400 to 2,000, and showed similar UV-Vis. absorption characteristics to that of foil fulvic acid. Transformation of 1,4-NPQ, which is non-reactive to Mn oxide, to the polymerized products via cross-coupling reaction in the presence of 1-NP was also verified. In this experimental conditions(20.5 mg/L, 1-NP, 2.5 g/L $MnO_2$, pH 5), the transformation of 1-NP into the oligomers and polymerized products were about 83% of initial 1-NP concentrations, and more than 30% of the reaction products was estimated to be water insoluble fractions, not extracted by $H_2O$ methanol. Results from this study suggest that Mn oxide-mediated treatment of naphthol contaminated soils can achieve risk reduction through the formation of oligomers md polymer precipitation.

• Korean Journal of Food Science and Technology
• /
• v.26 no.2
• /
• pp.178-183
• /
• 1994

The fresh perilla seed and tile one-year stored perilla seed were solvent extracted for their oil. On the other hand, the fresh seed and the stored seed were germinated in the dark at $25{\sim}28^{\circ}C\;for\;2{sim}3$ days and then solvent extracted. The above four kinds of perilla oil, that is, the oil from the nongerminated and fresh seed(NFO), the oil from the nongerminated and one-year stored seed (NSO), the oil from the germinated and fresh seed(GFO), and the oil from the germinated and one-year stored seed(GSO) were analyzed with regards to the chemical composition, and the effects of germination of the seed on the oxidative stability of perilla oil were studied. The iodine value and the saponification value were similar in all the perilla oils, but the acid value was increased by germination of the seed. The contents of free fatty acid and diacylglycerol were increased by germination of the seed, while the content of triacylglycerol was decreased. Of the polar lipid components, the content of phosphatidyl ethanolamine was greatly increased by germination of the seed. The contents of total tocopherol of perilla oil from the fresh seed and the one-year stored seed were 494 ppm and 439 ppm, respectively, and by germination of the seed increased to 560 ppm in GFO and 515 ppm in GSO, respectively. Especially a great change in the content of ${\gamma}-tocopherol$ was observed. The oxidative stability of perilla oil was increased by germination of the seed and the increase was distinct in the case of the one-year stored seed compared with that in the case of the fresh seed.

• Journal of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.441-447
• /
• 1985

Several benzanilides were prepared by acylation of anilines with substituted benzoyl chlorides. While 2-chlorobenzanilides were photocyclized, 2-methylbenzanilide and 2'-methylbenzanilide were cleaved to give photo-Fries type products. 2-Nitrobenzanilide and 2'-nitrobenzanilide were inert in the above conditions due to lowering energy of the excited state by the nitro group. N, N-dibenzoylaniline and N, N-di-(2-chlorobenzoyl) aniline gave photo-Fries type reaction products effectively. In the benzanilide photo-Fries type reaction the excited singlet state was believed to be involved, since no oxygen effect was observed on the reaction rate. Quantum yield for 2-methylbenzanilide is higher in nonpolar and less viscous solvents than in polar and viscous solvents. The solvent cage radical pair is suggested in the photo-Fries type reaction of benzanilides.

• Microbiology and Biotechnology Letters
• /
• v.40 no.4
• /
• pp.333-338
• /
• 2012

Lichens are a symbiosis between fungi, algae and cyanobacteria. Our group recently studied the antioxidant properties of some bacterial species isolated from Arctic lichens and we confirmed that they possess high antioxidant activities. In this paper, we investigated the antioxidant capacity of 5 microorganisms newly isolated from 4 Arctic lichen species, Cladonia sp., Sterocaulon sp., Umbilicaria sp. and Cetraria sp., using various solvent extractions. We carried out 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity test and ferric reducing antioxidant power (FRAP) assay. Also total phenolic and flavonoid content assays were performed. Among the bacterial culture extracts of the tested lichen-microorganisms, ethyl acetate extracts of Burkholderia sordidicola S5-B(T) had not only a high antioxidant activity (72.9%) when compared with the ascorbic acid used as the control (51.3%) in the DPPH assay, but also a high amount of phenolic content as well as flavonoid content. As a result, these lichen-microorganisms may be potentially useful sources of natural antioxidants.