• Title, Summary, Keyword: norvaline

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Electrooxidation of DL-norvaline at Glassy Carbon Electrode: Approaching the Modified Electrode for Voltammetric Studies of Hydroquinone and Catechol

  • Kamel, Mahmoud M.
    • Journal of Electrochemical Science and Technology
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    • v.5 no.1
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    • pp.23-31
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    • 2014
  • The DL-norvaline was electrochemically oxidized and deposited on the glassy carbon electrode surface using cyclic voltammetry (CV). The modified electrode was examined for electrochemical oxidation of hydroquinone (HQ) and catechol (CC). It exhibited good electrocatalytic ability towards their oxidation and simultaneous determination in a binary mixture using differential pulse voltammetry (DPV). The peak currents were linear to the concentration of HQ and CC, in the range from $5{\mu}M$ to $100{\mu}M$, and $4{\mu}M$ to $140{\mu}M$, respectively. The determination limits(S/N = 3) for HQ and CC were $1{\mu}M$ and $0.8{\mu}M$, respectively. The obtained modified electrode was applied to simultaneous detection of HQ and CC in water sample.

The Dissociation Constants of Valines in Aqueous Solution (수용액 중에서 발린류의 해리상수)

  • Jung-Ui Hwang;Yong-Woo Kwak;Jae-Won Jung;Chon-Ho Kil
    • Journal of the Korean Chemical Society
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    • v.35 no.2
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    • pp.105-110
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    • 1991
  • The dissociation constants of valine and norvaline in aqueous solution were measured by conductometric method in various temperatures and pressures. The properties of the dissociation reaction were discussed in term of the thermodynamic properties of reaction. These substituted effects on the dissociation reaction were discussed on the points of Hammett relation and net charge of the O and N-atom calculated from CNDO/2 method respectively.

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Antioxidant and Physicochemical Changes in Salvia plebeia R. Br. after Hot-air Drying and Blanching (열풍건조 및 데침 처리에 따른 배암차즈기(Salvia plebeia R. Br.)의 항산화 및 이화학적 특성 변화)

  • Jeong, Ji-Suk;Kim, Yong-Joo;Choi, Bo-Rum;Go, Geun-Bae;Son, Byeong-Gil;Gang, Suk-Won;Moon, Seung-Man
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.6
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    • pp.893-900
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    • 2014
  • The aim of this study was to investigate physicochemical changes in Salvia plebeia R. Br. (SPA) upon hot-air drying and blanching. After hot-air drying and blanching, total polyphenol and flavonoid contents were reduced from 96.64 mg and 48.40 mg gallic acid equivalent/g to 29.70 mg and 22.10 mg quercetin equivalent/g, respectively. DPPH radical scavenging activities at $25{\mu}g/mL$ of SPA were 94.5% for ascorbic acid, 84.3% for hot-air dried SPA, and 59.7% for blanched SPA and there was no significant difference between those of hot-air dried SPA and ascorbic acid as a positive control. Total sugar contents were 7.187% and 6.104% for hot-air dried SPA and blanched SPA, respectively. During the blanching process, sucrose and maltose contents decreased, whereas glucose and fructose contents increased. Glucose and fructose were converted into citric acid in blanched SPA, whereas sucrose and maltose were converted into tartaric acid, malic acid, and succinic acid. Fourteen kinds of amino acids were found, but methionine, lysine, glycine, histidine, and cysteine were absent. The proportion of essential amino acids was 61.76% upon hot-air drying, which was a relatively high amount. In addition, hot-air drying resulted in 1.40 mg/100 g of norvaline as well as 39.00 mg/100 g of GABA, which are non-amino acids. Therefore, Salvia plebeia R. Br. can be used not only as vegetables but also as highly useful and various health functional foods with antioxidant effects and excellent nutrition.