University:
York University
Course:
CHEM 2021 | Introductory Organic Chemistry II
Academic year:

2022
Views:

398

Pages:

4
Author:

Hallie Randolph

Part A: Extraction of Curcumin from Turmeric Mass turmeric ___1.00_____ g Volume isopropyl alcohol __100___ mL Part B: Spectrum of Standard Curcumin Solution 1. %Transmittance, %T, and absorbance, A, for the 50-fold diluted solution calculated as log(100/%T). (nm) %T 380 45 0.347 A 435 (nm) 18 %T 0.745 A 390 38 0.420 440 19 0.721 400 31 0.509 450 22 0.658 410 20 0.699 460 25 0.602 415 20 0.699 470 39 0.409 420 18 0.745 480 64 0.194 425 14 0.854 490 86 0.066 430 15 0.824 500 100 0 Maximum A __0.854_____________ Wavelength (nm) at Maximum A (λMax) __425 nm________________ To find mass % curcumin in unknown sample of turmeric: 1. Calculate concentration C of curcumin in the undiluted extract: Absorbance, A, of diluted extract at 425 nm: __0.854_______ c, conc. of curcumin in diluted extract: c = A/(ab) = 0.854/(110 x 1) = 7.764 x 10-3 g/L a = 110 cm-1 g-1L b (path length) = 1 cm C, conc. of curcumin in undiluted extract of unknown sample: 50 x c = 50 x (7.764 x 10-3) = 0.3882 g/L 2. Find mass % of curcumin in your sample of turmeric. Volume of extract: 100 mL = 0.100 L Mass Curcumin in Extract, C (g/L) x 0.100 L: = 0.3882 x 0.100 = 0.03882 g Mass turmeric: ___1.00_______ g Mass% Curcumin ∈ Turmeric= MassCurcumin ∈Extract Massturmeric x 100%= x 100%=3.882% ( 0.03882 1 ) ❑ Part C: Curcumin as a pH Indicator For each of the household solutions record the color after adding a few drops of curcumin indicator and then estimate the pH range of the solution: Household Solution pH Color Lemonade <8 Light yellow Baking Soda >8 Dark red Vinegar <8 Yellow Oxi Clean >8 Dark red Detergent <8 Yellow Water 7 (neutral) Bright yellow (same as turmeric) Soap >8 Light red Borax >8 Dark red pH ranges: pH < 7 is acidic pH = 7 is neutral pH > 7 is basic Instructor’s Signature_________________________________________ 1. Why was the extract diluted before taking its spectrum? The extract was diluted before taking its spectrum because this action only requires a small amount of extract for the experiment to be sufficient. If the extract wasn’t diluted, the absorbance would be too high and the measurement couldn’t be taken. According to Beer-Lambert Law, A = Epsilon x c x l. Epsilon is called molar absorptivity and this figure is large, l is path length and usually 1cm, and A is between 0 and 1, which means the concentration must be very small. That’s why the extract was diluted. 2. Compare the mass % of curcumin you obtained to actual values of 3-5 %. The mass % of curcumin I obtained is 3.882%, in the range of 3-5%. In my opinion, it’s a reasonable amount. 3. Within what range of pH values will the curcumin indicator change color? The curcumin indicator changes color within the range of pH 7.4 to 8.6 and larger than 8.6. If pH is from 7.4 to 8.6, the color will be yellow, and if pH > 8.6, the color changes to red. 4. Why do you think curcumin is difficult to absorb by the body when taken orally? The curcumin is difficult to absorb since the digestive system of a person is watery, but the curcumin dissolves in fat easier than in water. When the curcumin goes into the digestive system, most of it just ends up excreted by the body. The small amount absorbed will be metabolized (broken down) quickly. As a result, very little curcumin is available for body to use.