Pharmacognosy Laboratory
Microscopical identification of powdered clove
Select the crude-drug sample, mount it in chloral hydrate, place the slide on a compound microscope, focus at low and high power, scan the field for diagnostic elements and identify the drug with the evidence that supports it.
Objectives
- Prepare a cleared powder mount without air bubbles
- Use coarse and fine focus correctly at low and high power
- Recognise the diagnostic elements of clove powder
- Distinguish genuine clove from clove-stalk and mother-clove adulteration
Principle
Clove is the dried flower bud of Syzygium aromaticum. Powdered crude drugs are identified microscopically by their characteristic elements — cell types, cell contents, crystals, pollen — and by the absence of elements that would indicate an adulterant.
Chloral hydrate is the usual mountant for a general examination: when warmed it clears the tissue, so crystals, glands and stomata are visible. Starch is tested separately with iodine.
Start at low power to find and focus the specimen; switch to high power and use only the fine focus. Field of view = eyepiece field number ÷ objective magnification (18 mm ÷ 40 = 0.45 mm), which lets you estimate sizes.
The microscope image in this lab is a SCHEMATIC ILLUSTRATION drawn from the reference description, not a photomicrograph. Element sizes are to scale; their appearance is simplified.
Safety
- Chloral hydrate is harmful if swallowed and irritates skin and eyes: gloves, no mouth contact, wipe spills.
- Warm slides gently over a low flame or on a hot plate, holding them with a slide holder; never point a warming slide at anyone.
- Carry the microscope with two hands — one on the arm, one under the base. Clean any mountant from the objectives with lens tissue.
Apparatus and materials
- Compound microscope
- Microscope slides
- Coverslips
- Reagent bottles with droppers
- Crude-drug sample jars
- Spirit lamp
- Mounted needle and spatula
- Blotting paper
- Lab notebook
Clove, powdered (jar PG-07) · Chloral hydrate solution · Iodine solution N/50
Curriculum
Listed in the UoK Pharm-D practical syllabus (PHG-411 Pharmacognosy Lab-I, 2nd year, 1st semester: powdered drug examination — flower bud, Eugenia caryophyllus). The microscope view is a schematic illustration. Not faculty-reviewed.
- UoK — PHG-411 Pharmacognosy Lab-I, pcgnosy.pdf p. 2 — “Powdered Drug Examination … Flower bud: Eugenia caryophyllus.”
- HEC Pharm-D curriculum (2025) — related topic only — Pharmacognosy Basic-I, Semester III: “Powder microscopy of crude drugs” (no drug named).
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