1901: Secret Service Established
Counterfeiting
• In 1865, 1,600 different forms of currency in U.S.
• The amount of counterfeit currency increases 25% year
Preventative Measures
Paper-Based Identification of Counterfeiting
• Only one company in U.S. can make paper for currency
• Cellulose based paper w/red & blue threads
• Most other papers are stiffened by adding starch
Cellulose v. Starch Identification
Glycosidic Linkage
Functional Groups
Identification Of Unknowns
• Since 1995, many commercial chemical products have had a chemical “signature” mixed in to assist in their identification
• Unique functional groups and structures allow chemists to identify the date, source and purchaser of the chemical
Lab: Using Organic Indicators
• Purpose: To determine the specificity of four organic indicators and to apply them to the identification of unknown solutions
Chemistry of Organic Indicators
• Benedict’s Reagent: Copper ions in solution oxidized to cupric oxide, causing color change
• Lugol’s Solution: Potassium iodide sits in spaces between monomers, blocking out light, causing color change
• Biuret Reagent: Copper ions in solution reflect off of the amide functional group, causing color change
• Sudan IV: Molecules of dye bind to organic molecule based upon solubility
Protocol 1: Setup
• Obtain 5 test tubes and fill 1 with 5mL of water
• Mark the other tubes w/ a grease pencil to the same level
• Fill the remaining 4 tubes with 5mL of 1% starch, 1% glucose, 1% gelatin and 1% lipid respectively
Protocol 2: Benedict’s Test
• In the first test, add 5 drops of Benedict’s Reagent to each tube
• Place all four tubes in a hot water bath
• The first one to change color is the organic molecule for which benedict’s reagent is an indicator
Protocol 3: Lugol’s Test
• Clean up the tubes and restock with your standard solutions (water, 1% starch, etc.)
• Add 5 drops of Lugol’s to each tube
• NO HEATING IS NECESSARY
• The most drastic change is the organic molecule for which Lugol’s is an indicator
Protocol 4: Biuret Reagent Test
• Clean up the tubes and restock with your standard solutions (water, 1% starch, etc.)
• Add 5 drops of Biuret Reagent to each tube
• NO HEATING IS NECESSARY
• The most drastic change is the organic molecule for which Lugol’s is an indicator
Protocol 5: Sudan IV Test
• Clean up the tubes and restock with your standard solutions (water, 1% starch, etc.)
• Add 5 drops of Sudan IV Reagent AND 5 drops of Ethyl Alcohol to each tube
• Do not heat but shake up tube• The most drastic change is
the organic molecule for which Sudan IV is an indicator
• Note: This is a solubility-based test
Protocol 6: Identification of Unknown Mixtures
• Clean out your tubes and obtain 5mL of your 1st assigned unknown in each of four test tubes
• Add 5 drops of Benedict’s to the first tube, 5 drops of Lugol’s to the second, 5 drops of Biuret to the third tube and 5 drops of Sudan IV & Ethyl Alcohol to the 4th
• Heat only the Benedict’s• Record the changes and
determine which of the four unknowns is present in that mixture
• Repeat this procedure for the two remaining assigned unknowns.
UNKNOWN MIXTURE ASSIGNMENTS
• Group 1– Unknowns A, B, E
• Group 2– Unknowns C, D and F
• Group 3– Unknowns E, F and A
• Group 4– Unknowns A, D, F
• Group 5– Unknowns B, C and D
• Group 6– Unknowns B, C and E