IDENTIFICATION OF AN UNKNOWN ANALGESIC

IDENTIFICATION OF AN UNKNOWN ANALGESIC

INTRODUCTION

Objectives

The aim of this experiment is to identify a series of unknown drugs after isolation of the drug’s pure active compositions.

Background information

Analgesics are basically drugs that are used to relieve the symptoms of pain without blocking nerve impulses thus altering the sensory perception. Moreover, analgesics can be classified into two groups namely; the opioids and the anti-inflammatory drugs. Globally, millions of analgesics are consumed daily. Majority of the anti-inflammatory drugs are manufactured from pyrazolone, phenacetin, and salicylic acid in order to moderate pain (Bpharm, 2018). The two common types include the acetaminophen and the nonsteroidal anti-inflammatory drugs which include compounds like fenoprofen, naproxen and ibuprofen. The most common mild analgesic is the aspirin. Consequently. aspirin is taken by more than half of the adults in the United States.

On the other hand, opioids incorporate almost all synthetic chemical and natural compounds associated with morphine.  These drugs are made from opium which effects are sleep and induction of a peaceful state of the body. Some of the opioids include methadone, meperidine, codeine among others. Majorly, they are used in the reduction of pain associated with gallstones and kidney stones (Bpharm, 2018).

EXPERIMENT

Since the unknown analgesic contains both acidic and basic compounds, they out to be separated before recrystallization through a process called acid-base extraction. Due to the fact that the components have different solubilities in both acidic and basic solutions, the process of separation of the acidic and basic components of the analgesic. All the active components are highly insoluble in water and posses the following acidic functional groups.

Recrystallisation technique

This is termed as one of the best ways to purify solid compounds.

The process of recrystallization.

1. The impure solid compound is suspended in a solvent whereby it is insoluble at lower temperatures.
2. The solvent is heated whereby the solid mixture to be purified as well as the soluble impurities are dissolved leaving behind insoluble impurities.

• Filtration is recommended to remove insoluble impurities.

1. The solution is cooled to room temperature slowly then cooled further using an ice bath for crystallization.

Precautions

Rapid precipitation is discouraged since the solid impurities get embedded in the solid matrix of the precipitating compound.

Safety precautions

• Sodium hydroxide and hydrochloric acid spills should be cleaned immediately since they are highly corrosive.
• Tasting or ingestion of the chemicals is prohibited because the pure analgesics are biologically active.
• Precautions should always be taken seriously since ethanol is highly flammable.

APPARATUS

• Pills (with a colored coating)
• Erlenmeyer flasks
• Sodium Hydroxide (8%)
• Beakers
• Hydrochloric acid (10%)
• pH paper
• Ice bath
• Rubber policeman
• Ethanol
• Buchner funnel

PROCEDURE

Isolation of the active ingredient

• Put the pills into a small Erlenmeyer flask containing about 15 mL of water. Stir or shake them until the pills have almost completely disintegrated.
• Add 2 mL of 8% NaOH. Continue mixing the solution for 5-10 minutes, to allow all of the soluble material to dissolve.
• Remove the insoluble fillers and binders by suction filtration. Transfer the filtrate to a clean beaker.
• Slowly add 10% HCl solution to the filtrate, stirring well after each addition. Add enough HCl so that it tests as strongly acidic with pH paper. When the pH of the solution drops low enough, the drug will precipitate. This should require less than 5 mL.
• Cool the solution down in an ice bath to maximize yield. Isolate the solid by suction filtration, washing it well with cold water. Run the aspirator for a few minutes to remove as much water as possible.

Recrystallization

• Using your rubber policeman, gently remove the collected solid from the Buchner funnel. Do not use a metal spatula. Transfer this solid to the bottom of a small Erlenmeyer flask.
• Add about 5 mL of ethanol. Heat gently to dissolve the solid. If the solid does not dissolve once the ethanol begins to boil, add more in small portions.
• If solid impurities are observed, separate them by hot gravity filtration.
• Slowly add water to the hot solution, until it becomes cloudy. Once the solution becomes cloudy, stop adding water and add ethanol drop by drop until it clears again.
• Remove the Erlenmeyer flask from the heat and set it on the benchtop. Allow it to cool to room temperature. Solids should be observed forming in the flask during this time.
• Once the flask has cooled to room temperature, cool it in an ice/water bath. Once it is ice-cold, isolate the crystals by suction filtration, rinsing them with a small amount of ice-cold water.
• Remove the top of the Buchner funnel, and cover it loosely with a piece of filter paper. Store it in an uncovered, labeled beaker until it is required again.

RESULTS

Weight of the pills = 1.63g

Melting point = 114 degrees Celsius

Picture !: TLC result

DISCUSSION

The drug identification by TLC confirmed the drug was found to be acetanilide since its melting point was 114 degrees. The drug results after data analysis show that the drug impure since it melted with a range of temperatures indicating presence of impurities. The impurity included sodium sulfate. All the drugs were identified since they showed different melting points and pHs thus confirming that they were totally different. I would recommend that a more technological method is used in identification of these drugs since the manual way consumes a lot of time and is prone to errors.

References

Bpharm, C. (2018). List of Common Analgesics + Uses, Types & Side Effects – Drugs.com. Retrieved from https://www.drugs.com/drug-class/analgesics.html

Mickey, l. (2018). Thin Layer Chromatography Lab Analysis. Retrieved from https://www.odinity.com/thin-layer-chromatography/

Murray, R. (2016). Thin-Layer Chromatography – Analysis of Analgesics. Retrieved from https://adamcap.com/schoolwork/thin-layer-chromatography-analysis-of-analgesics/