Formation of blue or green precipitates indicates presence of anthocyanin. Test for Flavonoids. 2.5mL of Sodium hydroxide solution was added to 2.5ml of the extract. Occurrence of orange or intense yellow color indicates the presence of flavonoids. Test for Alkaloids.
This test is performed on-site, as delays between sample collection and testing may result in an alteration in oxygen content. The process includes divalent manganese salt precipitation by strong alkali to divalent manganese hydroxide. Next is the addition of potassium iodide or potassium hydroxide to create a pinkish brown precipitate.
This accounts for the precipitate formed. The iodine test is used to detect the presence of starch. Iodine is insoluble in water. Therefore iodine dissolved in potassium iodide solution to form potassium triiodide solution, then used as a reagent in the test.Iodine form a colored complex with polysaccharide; starch gives blue color when reacted with iodine, while glycogen and partially hydrolyzed starch will react to form a red-brown
Throughout the experiment, the mixture changed color from green, orange, to yellowish lime, and eventually clear. These color changes indicate a chemical change, which show that a reaction had occurred. In the first step when o-vanillin and p-toludine, imine was formed. The color change from green to orange suggests that imine appears as orange colored. In the second step, the addition of sodium borohydride reduced the imine into another derivative, which was yellowish lime color.
A few drops of phenolphthalein indicator is added into the test tube that was filled with 5ml of water. The magnesium ribbon was placed into the test tube. The observations were recorded. 2. The experiment was repeated with small particles of calcium with water.
When the aqueous layer was added to the vial, calcium chloride was then added to dry the solution. If the solution was dry enough, a large peak between 3300-3500 would have been present in the IR spectrum. In order to obtain the IR spectrum two Classification test were performed. The Bromine test and Permanganate test were used to determine if alkenes were indeed present in the solution. Both test were positive for the compound.
The mixture was finally made upto 5 mL with distilled water and placed in hot water bath at 95ºC for 1 h. After cooling, 1 mL of distilled water and 5 mL of the mixture of n-butanol and pyridine (15:1, v/v) was added. The mixture was vortexed and after centrifugation at 4000 rpm for 10 minutes, the absorbance of the organic layer (upper layer) was measured in UV-Vis spectrophotometer (Shimatzu) at 532 nm against blank using distilled water. TBA when allowed to react with MDA aerobically formed a colored complex [MDA-(TBA) 2 complex] which was measured with spectrophotometer. MDA concentration (measured as TBARS) was calculated as
Data Collection and Processing Raw Data Table 1: Amount of Iodine Reacting (± 0.05cm3) in the titration FT 1 FT 2 FT 3 FT 4 FT 5 Trial 1 1.9 1.8 1.8 1.5 1.6 Trial 2 2.1 1.8 1.7 1.5 1.6 Trial 3 2.1 2.0 1.8 1.5 1.5 Trial 4 2.5 2.3 1.7 1.6 1.5 Trial 5 1.9 1.8 1.6 1.6 1.4 Average 2.1 1.94 1.72 1.54 1.52 Analysis The results of Table 1 are shown graphically in Figure 2 where the calculated and measured Iodine Solution are plotted with respect to the amount of days. The graph can be observed, showing that the measured value of the iodine is very close to the theoretical one. It can be seen that each time the Vitamin C is frozen, the iodine solution reacting with the Acid decreases. This means that the Ascorbic Acid is being destroyed every time it is frozen. Volumetric Analysis Calculating the moles of iodine reacting Since the potassium iodide was mixed with the iodine to create triiodide so that the starch indicator could form the complex, it does not have to be
2.9. Estimation of Hydrogen peroxide (H2O2) 10 213 The concentration of H2O2 was determined by the method of Okuda et al (38). Fresh leaf 214 sample (0.5 g) was grounded in ice-cold 200 mM HClO4 and was then centrifuged at 215 1200 g for 10 min followed by neutralization of HClO4 of the supernatant with 4M KOH. 216 The insoluble KClO4 was eliminated by further centrifugation at 500g for 3 min. In a 217 total volume of 1.5 mL, the reaction mixture contained 1 mL of the eluate, 400 mL of 218 12.5 mM 3-(dimethylamino) benzoic acid in 0.375 M phosphate buffer (pH 6.5), 80 mL 219 of 3-methyl-2-benzothiazoline hydrazone and 20 mL of peroxidase (0.25 unit).
The different level of blue colour of the solutions after adding the iodine solution show the different concentration of starch concentration in it. The change in colour is due to the formation of polyiodide chains from the reaction of starch and iodine. The amylose in starch forms helices where iodine molecules assemble, forming a dark blue or black color. 1ml of starch solution with concentration 5000 are added to test tube A. 1 unit volume of the starch solution to be diluted plus 9 unit volumes of the solvent medium.