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SAMPLE 1 - InJoy Cocoa
Mass of sample : 10g
Mass of isolate : 0.05 g
Percent yield : 0.5%
SAMPLE 2 - Riccoa
Mass of sample : 10g
Mass of isolate : 0.11 g
Percent yield : 1.1%
Murexide Test
Sample 1- Positive; appearance of purple color
Sample 2- Positive; appearance of purple color
Figure 1.1 Theobromine structure
- Theobromine was discovered by a Russian chemist Alexander Vosresenskey.
- Formerly called as xantheose is an alkaloid belonging to methylxanthines.
- The structure of theobromine is similar to the structure of caffeine
Dragendorff's Test
Sample 1- Positive; appearance of orange pink precipitate
Sample 2- Positive; appearance of orange pink precipitate
Figure 1.2 Caffeine Structure
• top source of antioxidants
• it contains Magnesium and Iron
• In terms of medical applications, it can heal wound quickly, it helps to improve cardiovascular health,
• high blood pressure, cholesterol, obesity and constipation.
28 grams of cocoa contains 60 mg theobromine while the same amount of dark chocolate contains 200 mg.
Standard Curve
Concentration Absorbance
200 0.054
300 0.133
400 0.157
500 0.24
650 0.395
700 0.45
LOD Theoretical
(3 x std.dev)/slope = (3 x 0.15)/(7.82x10^-4)
= 575
LOD Theoretical > LOD experimental
T- TEST
(357.065-200)/(46/(√6))
= 8.36
8.36>6.869
tcalc>ttab
ANOVA
P-value
0.5154>0.265
Pcalc>Ptab
F-TEST
5.9874<19.3
Fcalc <Ftab
• Phytochemicals. (n.d.). Retrieved February 7, 2017,
from http://www.phytochemicals.info/phytochemicals/theobromine.php
• Przybyl, A. K., & Kurekk, J. (n.d.). Laboratory of Organic Chemistry (Natural and Pharmaceutical) (J. Milecki, Ed.).
• Health Benefits of Cocoa. (n.d.). Retrieved March 7, 2017, from https://www.organicfacts.net/health-benefits/other/health-benefits-of-cocoa.html
• Applied Science BTEC Nationals/Chemical Laboratory Techniques/Caffeine Extract. (n.d.). Retrieved from https://en.wikibooks.org/wiki/Applied_Science_BTEC_Nationals/Chemical_Laboratory_Techniques/Caffeine_Extract
-Isolation through reflux
-Final product was white precipitate
-Percent yield: Injoy Cocoa (0.5%) Riccoa ( 1.1%)
-Chemical test: Positive in Dragendorff's test and Murexide test
-T-test: standard is comparable to the sample
-LOD: method was considered to be accepted
Possible source of error:
-Refluxing Time