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Comparison of Ingredients in various Chocolates 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:

Most of us don't realize that Chocolate Candy is not a simple thing (unless we've been to Hershey Park in Pennsylvania), but a complex mixture of several key ingredients that actually react to produce the thing we know as "Chocolate". Cocoa Butter, Cocoa Powder, Sugar, Alkalis, Mono- and Di-Glycerides, Waxes, Resins, Flavoring agents, Coloring Agents, Starch, Milk, Eggs, Nuts..... YUMMY! While the Sugars are not very well seen by UV Detection on HPLC, almost all of the other components are seen with fair to good sensitivity. A Sample of Chocolate is prepared for injection on the HPLC and the Chromatograms from a variety of Chocolate types and brands are compared to show that there are measurable differences in grades of Chocolate. This is a QUALITATIVE Lab, since it would be very difficult to get Pure Standards to make a series of GOOD Calibration Standards. Organic chemicals like Vitamins, Alkaloids, Xanthines, Fatty Acids, Lipids, Sterols (not Steroids!), Amino Acids and Proteins can be seen by this simple Reverse Phase HPLC technique with moderately high resolution.

INSTRUMENTS NEEDED:

Model BLC-10 iso-HPLC w/ 254nm. UV Detector & a mixed 60%:40% Methanol-Water Solvent Computer operating Peak-Simple Software

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5 ml. Sample Syringe with Filter Cartridges(to remove particulates which damage the Column)

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100 uL Syringe INFO/Buy IT!

SUPPLIES:

1. Chunks of Known Chocolate Reference Materials: Milk, Dark, White & Bakers (all Hershey)

2. 250 ml. Pyrex Beaker

3. Disposable Pipets

4. "Hot-Plate" Mug Warmer(for preparing the Samples)

SAMPLES:

· Try to get the same TYPE of Chocolate (Milk, Semi-sweet, Dark, White, etc.) from different manufacturer BRANDS (Nestle, Cadbury, Ghirardelli, Baker's, etc.).

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