• Journal of the Korean Chemical Society
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• v.38 no.9
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• pp.682-686
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• 1994

New synthetic method of aminophosphonic acids by the amination of organoboranes containing phosphorus was developed. Thus, the hydroboration of diethyl 2-propenylphosphonate, diethyl 2-methyl-2-propenyl-phosphonate, diethyl 3-butenylphosphonate with borane-THF, followed by amination of the resulting organoboranes with hydroxylamine-O-sulfonic acid gave diethyl 3-aminopropylphosphonate, diethyl 3-amino-2-methyl-2-propylphosphonate and diethyl 4-aminobutylphosphonate, respectively. 3-Aminopropylphosphonic acid and 4-aminobutylphosphonic, acid were obtained by the hydrolysis of the corresponding esters, respectively.

• Journal of Electrochemical Science and Technology
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• v.2 no.1
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• pp.57-61
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• 2011

This paper describes an electrochemical immunoassay for simple, fast and quantitative detection of a urinary hippuric acid which is one of major biological indicator in toluene-exposed humans. The electrochemical system of immunoassay was based on the directly osmium complex conjugated with hippuric acid. With the competition between free hippuric acid (HA) and the osmium-hippuric acid conjugate (Os-HA) to bind with antibody hippuric acid (Anti-HA) coated onto gold nanoparticles, the electrical signals were proportional to urinary hippuric acid (HA) in the range of 0.01-5 mg/mL which is enough range to be used for in-field or point-of-care (POC) diagnosis. The proposed electrochemical method can be extended to the applications to detect a wide range of different small molecules in the field of health care.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1028-1032
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• 1997

Low-temperature crystallization method silver nitrate-impregnated silicic acid column chromatography were applied for the isolation of pure $\alpha$-linolenic acid(ALA) from perilla seed oil. ALA or 78% in purity(HALA; yield, 83%) was obtained from the fatty acid mixture(ALA, 65.7%) derived from perilla oil by the low-temperature crystallization method, when the mixture was frozen at -8$0^{\circ}C$ for 210min. ALA over 90% in purity(yield, 71%) was also obtained from HALA ethyl esters(ALA, 78%) by the silver nitrate-impregnated silicic acid column(100cm$\times$10cm, i.d.) chromatography. In addition, the silver nitrate-impregnated silicic acid could be semipermanently used for isolation of ALA, because $Ag^{+}$ ion was not dissociated from the stationary phase.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3239-3242
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• 2013

An improved rapid method for determination of the fatty acid composition using modified methylation procedure was compared with the AOAC reference procedure based on the methylation of fatty acid with the addition of BF3 catalyst before and while heating. The new method is useful for research and routine quality control and has a number of advantages over the reference procedure which are more rapid, simple and also reliable. Applicability of the modified methylation method was confirmed with three vegetable oil samples (palm oil, coconut oil and olive oil). Based on the validation method results, we obtained that a quite linear calibration curve of fatty acids was performed with $R^2$ in range of 0.9972-0.9994. The sensitivity of gas chromatography instrument was able to analyze the fatty acids up to a few ppm, the precision and accuracy were good enough with the %RSD between 1.5%-19.5% and the recovery of linolenic acid was 99.1% in the range of 80.0%-113.3%.

• Journal of the Korean Institute of Gas
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• v.19 no.3
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• pp.18-24
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• 2015

The flash point is one of the most important indicators of the flammabiliy of liquid solutions. The flash point is the lowest temperature at which there is enough concentration of flammable vapor to form an ignitable mixture with air. In this study the flash points of binary flammable solutions, 2-propanol+propionic acid and n-hexanol+formic acid systems, were measured using Seta flash closed cup tester. Particularly n-hexanol+formic acid system exhibited minimum flash point behavior. The measured values were compared with the calculated values using Raoult's law and optimization method. The calculated data by optimization method described the measured values more effectively than those calculated by Raoult's law.

• YAKHAK HOEJI
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• v.45 no.4
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• pp.387-396
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• 2001

The effects of ascorbic acid, thiols such as cysteine, n-acetyl-ι-cyteine, glutathione, thiourea, 2-mercaptoethanol and dithiotreithol and organic acids such as magic acid, citric acid, glycolic acid, taurine and kojic acid on polyphenol oxidate (PPO) activity were studied in order to establish if it reacts with oxidized product and/or directly inhibits the enzyme. To investigate the mechanism, the quantification of t-butylcatechol and 4-methylcatechol (phenolic compounds) as substates, their oxidized product and sulphydryl colorless additional compounds were determined by high performance liquid chromatograph (HPLC) method. Chromatographic results indicate that ascorbic acid, organic acids and lower level of cysteine reduced oxidized product of substrates back to their respective positions uf ο-diphenols. On the other hand, other thiols and high level of cysteine reacted with oxidative product of ο-diphenols and then produced sulphydryl colorless compounds. Cysteine apperars to have two types of mechanism of actions in the formation of oxidative products of substrates depending on its concentration; ascorbic acid-type and other thiols-types. The effect of ascorbic acid with thiols on polyphenol oxidase was determined by same method. Chromatographic results indicate that ascorbic acid was more reactive with oxidized product of substrates than thiols.

• Mass Spectrometry Letters
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• v.4 no.4
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• pp.75-78
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• 2013

A gas chromatography/mass spectrometric (GC/MS) method was developed as a candidate reference method for the accurate determination of essential fatty acids (linoleic acid, ${\alpha}$- and ${\gamma}$-linolenic acids) in food supplemental oil products. Samples were spiked with three internal standards (stearic acid-$d_{35}$, $^{13}C_{18}$-linoleic acid, and $^{13}C_{18}$-${\alpha}$-linolenic acid). Samples were then subject to saponification, derivatization for methylation, and extraction by organic solvent. For GC/MS measurement, an Agilent HP-88 column, designed for the separation of fatty acid methyl esters, was selected after comparing with other columns as it provided better separation for target analytes. Target analytes and internal standards were detected by selected ion monitoring of molecular ions of their methyl ester forms. The GC/MS method was applied for the measurement of three botanical oils in NIST SRM 3274 (borage oil, evening primrose oil, and flax oil), and measurement results agreed with the certified values. Measurement results for target analytes which have corresponding isotope-labeled analogues as internal standard were calculated based on isotope dilution mass spectrometry (IDMS) approach, and compared with results calculated by using the other two internal standards. Results from the IDMS approach and the typical internal standard approach were in good agreement within their measurement uncertainties. It proves that the developed GC/MS method can provide similar metrological quality with IDMS methods for the measurement of fatty acids in natural oil samples if a proper fatty acid is used as an internal standard.

• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.341-350
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• 2005

To assess the antioxidative activity of 12 medicinal plants on lipid peroxidation, twelves traditional medicinal plants extracted with 95% methanol were investigated the antioxidative activity using DPPH, thiocyanate acid method, and thiobarbituric acid (TBA) methods. Out of 12 medicinal plants extracted with methanol, the extraction yields of Sedum kamtschaticum was the highest values (49.46%) among them and Geranicum sibiricum, Saururus chinensis root (R), Agrimonia pilosa leaf (L), Agrimonia pilosa root was the lowest value (9.97%). Radical scavenging effect of the selected traditional medicinal plants extracted from different extract solution were examined by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical method. Antioxidative activity of methanolic extracts was higher than those of ethanol and n-hexane extracts. Scavenging effects in Sedum kamtaschaticum (R) determined by DPPH radical showed the highest among the 12 plants. The antioxidative effects of the first four medicinal plants were similar to those of butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT), but higher than that of tocopherol, which was used as a handled control. Antioxidative effects of each indicated concentration of the methanolic extracts on linoleic acid by thiocyanate method was the highest in Sedum kamtschaticum and followed by Geum japonicum and Agrimonia pilosa and their antioxidative effect were similar to those of BHA, and BHT, but higher than that of tocopherol. Antioxidative effects of the selected medicinal methanolic extract on linoleic acid by thiocyanate acid method were examined for 15 days. Peroxidation of control and tocopherol group occurred on days 5 and 9, respectively, but BHA, BHT, selected medicinal methanolic extract group did not occur until on day 15. Antioxidative effects of the selected medicinal methanolic extract on linoleic acid by TBA method were examined for 15 days. Antioxidative activity was similar to those obtained by thiocyanate acid method.

• Analytical Science and Technology
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• v.30 no.2
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• pp.82-88
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• 2017

Adenophorae Radix (AR) is a frequently used medicinal herb; because of its popularity, products containing similar herbal products are often sold as substitutes, especially if their morphology is similar. However, any analytical method to identify AR based on quantitative analysis is not registered in Korea, Japan and China Pharmacopoeias. This study developed a simple HPLC method to discriminate between authentic AR and substitutes. Linoleic acid was used as a marker compound of AR. Our optimized HPLC-UV conditions included a mobile phase of 90 % acetonitrile under isocratic condition, and a flow rate of 1.0 mL/min at room temperature. Detection wavelength was set at 205 nm. Linoleic acid was detected at 13.5 minutes for a total analysis time of 20 minutes. The standard herb of AR contained 0.025 % of linoleic acid, while four authentic AR samples and eight substitutes contained 0.040~0.071 % and 0.004~0.014 %, respectively. Comparison of the linoleic acid concentrations of the sample types to reference AR showed that among 12 samples, only the four samples were authentic. Thus, our HPLC-UV method, along with our suggested content criterion for linoleic acid concentration, can be used for the quick and accurate determination whether the herbal products are authentic AR or substitute.

• Journal of Dairy Science and Biotechnology
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• v.41 no.1
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• pp.34-43
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• 2023

Hydrolysis of whey-derived proteins using lactic acid bacteria (LAB) utilizes the mass culture method and fermentation of LAB to produce effective bioactive peptides. Whey protein has the biological potential of its precursors, but the active fragments may not be released depending on the hydrolysis method. As an alternative to these problems, the nutritional and bioactive functionality of the hydrolysis method have been reported to be improved using LAB for whey protein. Peptide fractions were obtained using a sample fast protein liquid chromatography device. Antioxidant activity was verified for each of the five fractions obtained. In vitro cell experiments showed no cytotoxicity and inhibited nitric oxide production. Cytokine (IL [interleukin]-1α, IL-6, tumor necrosis factor-α) production was significantly lower than that of lipopolysaccharides (+). As a result of checking the amino acid content ratio of the fractions selected through the AccQ-Tag system, 17 types of amino acids were identified, and the content of isoleucine, an essential amino acid, was the highest. These properties show their applicability for the production of functional products utilizing dietary supplements and milk. It can be presented as an efficient method in terms of product functionality in the production of uniform-quality whey-derived peptides.