Determination of Caffeine Content in caffeinated beverages using HPLC
Caffeine (1,3,7-trimethylxanthine) a purine alkaloid is the principle stimulating constituent in 60 plant species including tea, coffee, cocoa and so on. Besides tea and coffee, caffeine is also very widely consumed through a wide range of dietary products, like cocoa beverages, energy drinks, soft drinks etc. Caffeine is a white, odourless powder with a slightly bitter taste. As a derivative of the xanthine nucleus, caffeine has pharmacological properties. It is a central nervous system and metabolic stimulant and is used both recreationally and medically to reduce physical fatigue and restore alertness when drowsiness occurs. It produces increased wakefulness, faster and clearer flow of thought, increased focus, and better general body coordination. Caffeine does not accumulate in the body over time and is normally excreted within several hours of consumption.
Objective:
To determine the concentration of caffeine in caffeinated beverages and compare that to the ones reported on the label.
Experimental setup:
The following were the HPLC conditions:
HPLC model LC2030 (Simadzu Corporation)
Zorbax Eclipse Plus 18 C Column, pore size 5μ, internal diameter 4.6nm and length 150 mm.
Flow rate, 1 ml/min (constant),
Column temperature at 40°C
UV detector set at 272 nm
Mobile phase: HPLC grade Water: Methanol (60:40)
Sample injection volume: 10 μl
The following standard solutions will be prepared using the C 1 V1 = C 2 V2 from a stock standard solution in a 10 mL volumetric flask. You will be provided with a 100 mg/L stock solution, calculate the volume of standard solution necessary to make the following:
Calibration
standard in
mg/L
Certified standard
concentration in
mg/L
The final
volume in mL
Initial volume
in mL
Initial volume
in μL*
0 100 10.0 ? ?
0.5 100 10.0 ? ?
1.0 100 10.0 ? ?
5.0 100 10.0 ? ?
10.0 100 10.0 ? ?
20.0 100 10.0 ? ?
You will be using a micropipette to perform the dilutions.
Introduction (8): Minimum word limit: 300 words
In your introduction focus on theory and background for the experiment you are performing. Include any important chemical reactions or calculations that are key to the experiment. Inclusion of reactions and calculations must be discussed and not simply placed in this section.
Lastly, include an industry/research related adaptation (application) of the main technique (e.g. Iodometry, gravimetric, etc…) used in the experiment. This should provide a summary of the work being done and how it relates to the experiment and should also include in-text citations (at least three citations not including lab manual and any safety information related links).
Materials (2): List out all materials and chemicals required (includes glassware, chemicals, and instrumentation used).
Safety (4): Provide the safety information for each chemical used in the experiment. This includes even nonhazardous chemicals such as water.
Each chemical should have the following information provided: Hazards Identification (section 3 of SDS) Handling (section 7 of SDS) Personal Protection (section 8 of SDS)
Procedure (4): Do not copy the procedure from the lab manual. Come up with your own plan, which should briefly but comprehensively cover all the procedure you will perform. You can format this section in either paragraph, bullet point, or flow chart format. Include mock calculations used (formulae..)
References (2): In text citations must be provided and ACS formatted citations must be used when creating the citation.
