(b) For staining thin blood films or combination thin/thick smears, Triton
X-100 in 0.01 concentration is used. Higher concentrations will lyse the erythrocytes.
For malarial thick smears, a concentration of 0.1 percent is preferred. For staining thick
films for microfilariae, 0.5 percent is recommended.
c. Field's Stain for Malarial Parasites.
(1)
Preparation of reagents.
(a) Solution A.
Methylene blue .................................................. 0.80 gm
Azure B (American stain) .................................. 0.50 gm
Sodium phosphate, dibasic, anhydrous ............ 5.00 gm
Potassium phosphate, monobasic, anhydrous.. 6.25 gm
Distilled water, q.s ............................................. 500.00 ml
STEP 1: Dissolve a large portion of the phosphate salts in a 500 milliliter volumetric
flask and add enough water to prepare 500 milliliters of solution.
STEP 2: Grind the remainder of the salts with the azure in a mortar and add this
mixture to the solution, mix well, and allow to ripen for 24 hours. Filter and
use the solution as needed.
(b) Solution B.
Eosin ............................................................... 1.00 gm
Sodium phosphate, dibasic, anhydrous ............ 5.00 gm
Potassium phosphate, monobasic, anhydrous.. 6.25 gm
Distilled water, q.s ............................................. 500.00 ml
STEP 1: Dissolve the phosphate salts in a portion of the water. Add the stain. Add
enough water to prepare 500 milliliters of solution.
STEP 2: Allow the solution to ripen for 24 hours. Filter and use as needed.
(2)
Procedure. Prepare a thick smear as for Giemsa stain.
STEP 1: Dip the smear two to three times into solution A.
STEP 2: Tap the slide on paper towels to remove excess stain. Immerse the slide
immediately into distilled water. Dip three to four times.
MD0841
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