Page 75 - Practical book PC406-MNU-2025

MANSOURA NATIONAL UNIVERSIY
PHARM D- CLINICAL PHARMACY LEVEL II INSTRUNENTAL ANALYSIS (PC 406)

Application: TLC ANALYSIS OF ANALGESIC DRUGS

Sample: Mixture prepared from commercial analgesic tablets (M).

Reference Solutions: standard reference solutions of three standard compounds often used

in analgesic formulations (Aspirin AS, Acetaminophen AC and Ibuprofen IB)

Mobile phase: 0.5% glacial acetic acid in ethyl acetate. The small amount of glacial

acetic acid suppresses ionization of the aspirin, allowing it to travel upward on the

plates. Without the acid, this compound does not move.

Stationary phase: a silica gel coating with a fluorescent indicator.

N.B.:

 After developing, you will observe your plate and a reference plate under illumination

from a short-wavelength UV lamp.

 When using the UV lamp, you must be careful not to operate the lamp outside of the

viewing chamber, and always wear the safety glasses provided. Under these

conditions, some of the spots will appear as dark areas on the plate, while others will

fluoresce brightly.

 This difference in appearance under UV illumination will help distinguish the

substances from one another.

 Handle the plate carefully, the solvent level must not be above the spots on the plate

or the samples will dissolve off the plate into the reservoir instead of developing.

 Do not rinse the developing jar or beaker with water as the presence of water

hurts the developing process.

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