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STEM Electrophoresis with Food DyesBio-Rad Biotechnology Explorer™ IDEA and STEM Kits
Biotechnology Explorer™ | explorer.bio-rad.com2
Instructors - Bio-Rad Curriculum and Training Specialists
Sherri Andrews, Ph.D., Eastern US
Damon Tighe, Western US
Leigh Brown, M.A., Central US
Biotechnology Explorer™ | explorer.bio-rad.com3
Why Use Bio-Rad?
Guaranteed to work
Easy to prep
Cost Effective per student group
Easy, inexpensive first exposure to electrophoresis
Independent inquiry opportunities for what dyes are present in food items, what is the charge of the dyes, can they be separated based on charge/size?
Engineering inquiry with STEM kit ranging from optimizing metal composition and diameter for electrodes, gel matrix composition, buffer composition, etc.
Extensions including paper chromatography, spectroscopy, and researching food dyes commonly used
Biotechnology Explorer™ | explorer.bio-rad.com4
Separation technology: How do you separate two or more compounds from each other?
Materials to be Separated Property Used to Separate Components
Explanation
Iron filings from other metals Magnetism Iron filings will be attracted to a magnet while other metals will not
Salt from sand Solubility Salt will dissolve in water and can be separated from the sand
Caffeine from coffee beans Solubility A solvent is used that selectively dissolves the caffeine (such as dichloromethane or ethyl acetate) but not most of the remaining coffee oils
Ethanol from fermented grain Boiling point Ethanol will boil off at a lower temperature than the other components of the fermented grain
Wheat from chaff Density Wheat kernels are more dense and will fall to the ground while chaff can be blow away by the wind
Tea from tea leaves Size Filtration can be used to separate the liquid extract from the large tea leaves
Biotechnology Explorer™ | explorer.bio-rad.com5
Electricity can be used to separate molecules by charge
Acetate ions Tris ions- +
+
-
+
--
-
-
+
+
+
+
- ---
+ ++
Apply an electrical charge
CH3 CO
O-
HO CH2 C CH2 OH
NH3+
CH2 OH
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Sieves can be used to separate materials by their size
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Electrophoresis separates molecules by CHARGE and SIZE
Molecular sieve
Electricity
Electrophoresis means “to carry with electricity”
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Food dyes – What have you recently eaten?…
Did you eat any cheddar cheese? Was it orange?
Starbucks Strawberry Frapuccino?
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Food dyes – Color tells our brains about foods. What flavor is this Skittle?
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Food dyes – We have been dying our foods for hundreds of years
In the early 1800s some cheese and cayenne pepper was colored with LEAD tetroxide
Pickles with COPPER sulfate
Green tea with COPPER carbonate
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Food dyes - Regulation
There was NO control or regulations on food dyes until the early 1900s in the US
•Food and Drug Administration (1902)•Due to public outcry over adulterated foods •Upton Sinclair – The Jungle (1906)•Elixir sulfanilamide Poisoning, 100 dead (1937)
Food Drug and Cosmetics Act (1938) •Synthetic Dyes – Seven approved for use•Natural Dyes (derived from plants or animals) can also be used and are not regulated
Biotechnology Explorer™ | explorer.bio-rad.com12
FD&C Dyes and Natural dyes
FD&C Synthetic Dyes
FD&C Red 40 or FD&C Red 40 LakeFD&C Yellow 6 or FD&C Yellow 6 LakeFD&C Yellow 5 or FD&C Yellow 5 LakeFD&C Blue 1 or FD&C Blue 1 LakeFD&C Blue 2 or FD&C Blue 2 LakeFD&C Red 3 or FD&C Red 3 LakeFD&C Green 3 or FD&C Green 3 Lake
Natural DyesBeetroot red or betanin (from beets)Curcumin (from tumeric)Caramel coloring (from sugar)Annatto (seeds of achiote trees)Carminic acid, carmine, or cochineal (from ground up beetle abdomens)Lycopene (from tomatoes, watermelons, papayas, and red carrots)
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Food dyes in the news
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Food dyes have an intrinsic SIZE and CHARGE and thus can be separated using Electrophoresis
Food dye Molecular weight
Charge
FD&C Blue 1 792.86 -2
FD&C Yellow 5 534.37 -3
FD&C Yellow 6 452.37 -2
FD&C Red 40 496.43 -2
Carminic Acid 492.38 0
Beetroot red 551.48 +1
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So how do we design an electrophoresis chamber to separate food dyes?
Dye Electrophoresis Commercial versus built box comparisons
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Combining Science, Engineering and Math to Develop a Separation Technology
Engineering – Design parameter based; no single “correct answer”
Science – Hypothesis driven; try to find specific cause/effect
Conducts well, has low reactivity, inexpensive
Understanding the chemistry of metals in salt solutions, physics of conductivity and currents
Best electrode material
Best gel matrix
Conducts electricity, moldable, inexpensive, non-toxic, correct pore size
Polymer chemistry, melting points, gelling properties
Mea
sure
men
ts
An
alys
is
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What are some of the design factors we want to think about?
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Dye extraction from candies
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Building and running your electrophoresis system to separate the dyes
Biotechnology Explorer™ | explorer.bio-rad.com20
Building and running your electrophoresis system to separate the dyes
Biotechnology Explorer™ | explorer.bio-rad.com21
Building and running your electrophoresis system to separate the dyes
Biotechnology Explorer™ | explorer.bio-rad.com22
Building and running your electrophoresis system to separate the dyes
Biotechnology Explorer™ | explorer.bio-rad.com23
Building and running your electrophoresis system to separate the dyes
Biotechnology Explorer™ | explorer.bio-rad.com24
Extensions
Paper chromatography Spectroscopy Food diary Electrochemistry study
– pH changes at the cathode and anode– Effect of material choice for electrode
Optimization of STEM box system– Electrode material choice and thickness– Different materials for gel thickness– Impact of TAE Concentration and Volume– Gel percentages
Copper electrode
Gelatin matrix