repeated for ascorbic acid concentration. All test tubes (ethyl acetate soluble fraction‚ ethyl-3-hydroxy-5-methoxy-4-methylbenzoate‚ ascorbic acid‚) labeled separately were shaken well and incubated in the dark at 25oC for 30 minutes. Then the Kinetic absorbance was recorded at 734 nm by spectrophotometer after 1 and 6 minutes for each concentration and mean was taken for each reading. The potential to scavenge the ABTS radical was calculated using the following
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water using the concentration calculations in vials. Seven cuvettes were obtained. One cuvette was filled with de-ionized water and one cuvette with penny solution. Five cuvettes were filled with the copper standards. The computer was set up and the absorbance of each of the solutions at 635 nm was measured. Chemical Equations: Dilute Acid 8H3O+ (aq) + 2NO3- (aq)  2NO (g) + 12H2O (l) Strong Acid 4H3O+ (aq) + NO3- (aq)  2NO2 (g) + 6H2O (l) Zinc Reaction with Acid 2H3O+ (aq) 
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measured their absorbance levels after water bath treatments. The more absorbent the solution was the less hydrogen peroxide there was in the solution. This means the peroxidase was able to break down the hydrogen peroxide. The less absorbent the solution the harder it was for peroxidase to break down hydrogen peroxide. Introduction Enzymes are proteins that catalyze chemical reactions. This means that they lower the
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saliva. A spectrophotometer set to 450nm was used to measure the effect of lysozyme on bacteria. The absorbance or optical density was measured for each sample at specific times with a total measuring time of twenty minutes. In this experiment‚ it was shown that lysozyme inhibits microbial growth in saliva and synthetic tears and in lysozyme standard control. The results showed a decrease in absorbance readings over time as the lysozyme activity was observed. Introduction In 1922‚ Alexander Fleming
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Examining the activity rate using DCIP and a spectrophotometer of succinate dehydrogenase isolated from Brassica oleracea mitochondria via mechanical disruption and differential centrifugation Introduction Mitochondria are important cellular organelles located in the cytosol of cells and is believed to have originated through an endosymbiotic relationship. The unique double layered membrane structure is responsible for the production of the primary energy currency of the cell; adenosine triphosphate
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iron (III) and thiocyanate ion. By using the colorimeter we determined the absorbance of each mixture once it reached equilibrium. Looking at the equation above we see that the mole to mole ration between SCN- and FeSCN2+ is 1:1 so we can simply set up a ratio using the absorbancy to find the consentration of FeSCN2+ : (where Absorbance 1‚ Absorbance 2 and [FeSCN2+ ] 2 are already known) Absorbance 1 = [FeSCN2+ ] 1 Absorbance 2 = [FeSCN2+ ] 2 We then pluged the determined value of [FeSCN2+ ] 1 to
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A Study to Determine the Level of Iron and Copper in Kuala Terengganu Estuary Muhammad Ali Azraei Bin Raduan ( UK32844 ) Lecturer Dr. Kesaven a/l Bhubalan Introduction : Kuala Terengganu River estuary (5.32°-5.35°N‚ 102.95°-103.15°E) is situated on the east coast of peninsular Malaysia facing the South China Sea (figure 1). Generally‚ the Kuala Terengganu River estuary is relatively small and shallow. The total area of the estuary is approximately 8 km2
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ORIGINAL ARTICLE The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity Philip Molyneux Abstract Molyneux‚ P. The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity Songklanakarin J. Sci. Technol.‚ 2004‚ 26(2) : 211-219 The use of the stable free radical diphenylpicrylhydrazyl (DPPH) to estimate the activity of antioxidants is reviewed. Current applications of the method are examined‚ particularly
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Total Volume (ml) 5.0 5.0 5.0 5.0 5.0 5.0 Final protein concentration (mg ml-1) 0 2 4 6 8 10 Absorbance 0.000 0.092 0.163 0.272 0.363 0.474 Table 2: Experimental protocol for determining the protein concentrations of silverbeet grown in the sun and shade Sun Shade Column for modified procedure(s) Procedure Protein concentration (ml) 1 1 0.4 0.4 Biuret reagent (ml) 4 4 4 4 Absorbance 1.104 0.908 0.465 0.363 Protein concentration derived from standard curve (mg ml-1) - - 10.2 8 Protein
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DATE PERFORMED: JULY 20‚ 2007 SPECTROPHOTOMETRIC DETERMINATION OF EQUILIBRIUM CONSTANT FOR A REACTION ABSTRACT UV-VIS spectrophotometry is one of the most widely-used methods for determining and identifying many inorganic species. During this experiment‚ this spectrophotometry was used to determine the equilibrium constant‚ Keq‚ of the Fe3+(aq)+SCN-(aq)↔ FeSCN2+(aq) reaction. By determining the amount of light absorbed‚ the concentration of the colored FeSCN2+ solution was also quantitatively
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