Separation and Measurement of Caffeine in Sodas
by Liquid Chromatography
INTRODUCTION:
The world of Analytical Chromatography involves the
separation of the individual components in a Sample, then the measurement of
their optical / spectral properties. In the realm of Organic Chemicals, there
are VOLATILE Compounds (low boiling points, easily evaporated, like most
Solvents) and NONVOLATILE Compounds (high BP/MP, usually solid materials, like
many drug and plastic chemicals). There
are many cases where the organic material is NOT Volatile or would decompose
under the temperatures necessary to cause it to boil (evaporate). In such
instances, the popular technique of High-Performance Liquid Chromatography is
available.
PURPOSE:
Using the Mini-LC system optimized for the separation of
Caffeine and other components in the Soda "matrix", and a simple 250
PPM Standard of Caffeine in Water, we can very quickly and easily determine the
amount of Caffeine in a series of popular Sodas. The ability of the HPLC
to "separate" and "isolate" the Caffeine from all of the
other material in these complex blends of sweeteners, coloring agents and preservatives
allows us to make an accurate comparison of these "Unknown" Samples
to the Caffeine Standard.
INSTRUMENTS NEEDED:
EDU-DLC10-HPLC w/ 254nm. UV Detector
& a mixed 60%:40% Methanol-Water Solvent INFO/Buy IT!
Computer operating Peak-Simple Software
100 uL Syringe INFO/Buy
IT!
SUPPLIES:
- Vial
of 250 PPM Caffeine Standard in Water (similar "matrix" to the
Sodas) - Vials
of Soda (degassed):
·
Coke
·
Diet Coke
·
Caffeine-Free Coke
·
Surge
·
Tab
SAMPLES:
· Test sample Sodas that have been shaken to drive off the
excess CO2 bubbles as follows: If using your OWN Soda, be sure to pour it
back and forth several times into a cup to help remove the excess Carbon Dioxide (carbonation)
that might affect the quality analysis.
·
Try different generic
Colas, Root Beer, Dr. Pepper, Iced Teas, Brewed Teas & Coffees (no cream!)
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this experiment * Must be a registered member!
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