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