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Stains for wet preparations following concentration by the formol-ether method. 1. Lugol's iodine solution (Double strength) Reagent 1
Potassium iodide 20 g Iodine 10 g Distilled water 100 mL
Add potassium iodide to the distilled water; when dissolved, add the iodine crystals. Store in a brown bottle. The solution remains stable for many weeks, but if it is not used after some months, a fresh
batch of reagent must be prepared.
Reagent 2 25% glacial acetic acid Working Solution Mix equal parts of reagent 1and reagent 2 for use.
Comment The addition of iodine to a stool concentrate highlights the internal inclusions of cysts; e.g. the nuclei and glycogen mass, thus aiding their identification. For example, the
addition of iodine enhances refraction of nuclei of 2. Acridine orange1 Stock solution.
0.1% acridine orange in distilled water.
Working solution.
Stock acridine orange 1 mL Glacial acetic acid 0.5 mL Buffered water pH 6.8 8.5 mL
Add an equal volume of stain to the concentrate. Examine the deposit under UV light after 30 minutes. Comment
The addition of acridine orange to a faecal concentrate highlights the chromidial bars of Entamoeba coli, Entamoeba histolytica/dispar and Entamoeba hartmanni, which fluoresce bright green.
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| [UKNEQAS Parasitology] [Diagnostic procedures] [Protozoa] [Helminths] |