دانلود رایگان ترجمه مقاله تعيين محلول كاتچين در محلول آبی با استفاده از روش شيميوميومينسانس – اسپرینگر ۲۰۰۵
دانلود رایگان مقاله انگلیسی تعیین مقدار کاتچین در محلول آبی توسط روش کمیلومینسانس به همراه ترجمه فارسی
|عنوان فارسی مقاله:||تعیین مقدار کاتچین در محلول آبی توسط روش کمیلومینسانس|
|عنوان انگلیسی مقاله:||Determination of Catechin in Aqueous Solution by Chemiluminescence Method|
|رشته های مرتبط:||شیمی، زیست شناسی، بیوشیمی، علوم گیاهی، شیمی تجزیه و شیمی آلی|
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|نشریه||اسپرینگر – Springer|
مقاله انگلیسی رایگان
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بخشی از مقاله انگلیسی:
A method to determine catechin in aqueous solution by measuring chemiluminescence intensities using a stopped flow system has been studied. The lucigenin-hydrogen peroxide chemiluminescence reaction was chosen for the determination of catechin. Fe(II) ion was added to the chemiluminescence system to increase the sensitivity. The chemiluminescence intensity from the lucigenin system was increased by the addition of catechin. Effects of flow rates of reagent and sample and concentrations of lucigenin, hydrogen peroxide, Fe(II) ion and KOH were investigated. The calibration curve for catechin was linear over the range from 1.0×۱۰-۳ to 1.0×۱۰-۷ M and the detection limit was 3.0×۱۰-۷ M under the optimal experimental conditions.
Catechins are a group of polyphonic compounds abundantly contained in green tea. The main polyphonic components in green tea are (−)-epicatechin (EC), (−)- epicgallocatechin (EGC), (−)-epicatechin gallate (ECG), and (−)-epigallocatechin gallate (EGCG). Catechins are considered to exert protective effects against cancer and inflammatory and cardiovascular diseases [1–۳]. This suggests that polyphenolic compounds like catechins may play an important role in scavenging free radicals such as hydroxyl radicals, peroxyl radicals, superoxide anion radicals, and nitric oxide in living systems [4–۱۲]. Several conventional detection techniques for catechin exist: HPLC-UV detection [13–۱۶], electrochemical detection [2,18] and chemiluminescence method [2,3,18]. Among these approaches, the chemiluminescence method is considered the most sensitive due to the fact that it does not require an excitation light sources as do fluorometry and spectrophotometry analyses.The purpose of this paper is to evaluate the antioxidant activity of catechin using chemiluminescence in order to determine the catechin concentration. The optimum analytical conditions such as concentrations of KOH, H2O2, lucigenin, and Fe (II) ion and flow rates were studied.
Lucigenin (bis-N-methylacridinum nitrate) and catechin hydrate (98%) were obtained from Aldrich (Milwakukee, WI). Hydrogen peroxide (30%) and KOH (min 85%) were purchased from Junsei chemical Co. Ltd. and Duksan (Duksan Pure chemical Co. Ltd) respectively. Ferrous Ammonium sulfite was obtained fromWako Pure chemical industries. Ltd. Deionized water was obtained by means of a Millipore (Bedford, MA) Milli-Q water system and used through out the whole experiment. Catechin stock solution was prepared by dissolving an appropriate amount in deionizied water, and then diluted with deionized water to give a concentration of 1.0 × ۱۰−۲ M.
The diagram of an automated flow injection analyzer used in the chemiluminescence measurement is shown in Fig. 1. The flow system employed in this work consisted of two peristaltic pumps (Ismatec Model MS-4 Reglo/6-100, Glattbrugg-Zich, Switzerland). One (Pump I) delivered a chemiluminogenic reagent solutions, H2O2, KOH, and Fe (II). The other (Pump II) drained all sample solution. The sample solution was mixed with flow cell. PTFE tubing (i.d. 0.040) was used to connect all the components of this system. A bifurcated optical fiber bundle (Model 77533, Oriel, Straford, CT) was screwed to the flow cell for the position of the sensing tip of the optical fiber to be the same for each measurement. The flow cell was housed in a laboratory made light tight chamber to remove all the unnecessary stray light. One end of the fiber bundle was fixed at 10 mm before the emission port and the other end at 10 mm before the excitation port of the cell component of spectrofluorometer (Model FL 111, Spex, Edison, NJ). To record emission and excitation spectra, a 450 W Xe lamp was used. To measure chemiluminescence intensity, the Xe lamp was shut off and the luminescence emitted from the cell was fed to a photomultiplier tube (Model R928, Hamamatsu, USA). The voltage used for the photomultiplier tube was 950 V. The acquisition mode used was signal/reference (S/R) for the excitation and emission spectra and signal (s) for the chemiluminescence measurements. The chemiluminescence intensity at 473 nm was monitored for the determination of catechin. For the chemiluminescence measurements, the integration time and slit width were 1 s and 0.50 mm, respectively.