Analyzing Drug Components Using Thin-Layer Chromatography

Tanner Nielsen

CHMY 321-011

TA: Jeffrey Richards

11 September, 2015

Lab #1

Analyzing Drug Components Using Thin-Layer Chromatography

Introduction:

The purpose of the experiment was to identify the components of an unknown analgesic drug tablet and identify the tablet as one of six possible commercial drugs. The six commercial drugs were Advil, Anacin, Aspirin, B.C. Tablets, Excedrin, and Tylenol. Each drug contained 1 or 3 of these substances: Aspirin, Acetaminophen, Ibuprofen, Salicylamide, and Caffeine. Thin-Layer Chromatographic Analysis was utilized in order to correctly identify the components of the unknown analgesic drug. Knowing the components of the unknown allowed for the drug to be identified as one of the six commercial drugs.

Thin-Layer Chromatography (TLC) was the method used to identify the drug. TLC is a chromatography technique used to separate solutions. TLC is done on a plate that is coated with a layer of absorbent material, in this case a silicone based material. After the solutions have been spotted onto the plate, a solvent is drawn up the plate due to capillary action. Capillary action has to do with the intermolecular forces between the liquid and surrounding solid surface. Different substances ascend the plate at different rates which results in separation. The TLC in the experiment used ethyl acetate/acetic acid (200:1) as the developing solvent. There were 6 solutions used as the analytes in the TLC. The solutions included: Aspirin, Acetaminophen, Ibuprofen, Salicylamide, Caffeine, and the unknown drug solution which was created using the powder from the drug and 1:1 ethanol/dichloromethane. After the TLC had been completed, the retention factors of each spot were calculated. The Retention Factor (Rf) is calculated by the distance traveled by the sample divided by the distance traveled by the solvent. The retention factors of the 5 components were then compared to the unknown drug’s retention factors. Knowing the components of the unknown analgesic , the drug was identified as one of the 5 commercial drugs.

Procedure/Observations:

List of Lab Materials:

Flat-Bladed Spatula

Small Test Tube

Stirring Rod

Filter-Tip Pipet

Small Vial

Silica-Gel TLC PLate

Micropipet

Pencil

Unique Tools:

Short-Wavelength (254 nm) Ultraviolet Light (do not look directly under lightsource)

Developing Chamber (containing a paper wick)

Chamber Cover

Silica-Gel TLC PLate

List of Chemicals:

Ethyl Acetate/Acetic Acid (200:1)

Quarter Tablet of Unknown Analgesic Drug

1:1 Ethanol/Dichloromethane

Acetaminophen

Salicylamide

Caffeine

Ibuprofen

Aspirin

(the chemicals were worked with under the fume hood)

First, ethyl acetate/acetic acid (200:1) was added to a developing chamber, containing a paper wick, to a depth of about 5 mm. The chamber was then covered with a lid and put under the fume hood. Next, a quarter tablet of the unknown analgesic drug was grinded into a powder by using a flat-bladed spatula. The powder was grinded on a watchglass. The powder was then carefully transferred to a small test tube. 2.5 mL of 1:1 ethanol/dichloromethane was then added to the test tube containing the powder. The powder was dissolved as much as possible into the solution by mixing the solid into the solvent using a stirring rod. Next, using a pipet that was filled with cotton to act as a filter, the solution was transferred to a small vial. The solid was left behind in the test tube. Next the 5 standard solutions of aspirin, ibuprofen, caffeine,salicylamide, and acetaminophen were obtained. A starting