Field's Stain A is used as staining solution for blood films for Spirochaetes, Protozoa and other purposes.

Ingredients

1. Methylene blue 1.300 gm
2. Potassium phosphate 6.250 gm
3. Disodium hydrogen phosphate 5.000 gm
4. Fresh distilled water 550.000 ml
5. **Formula adjusted, standardized to suit performance parameters

Directions

1) Dry the blood film and immerse in methanol for 2-3 minutes.
2) Blow off with Fields Stain A (S008) for 2-3 seconds.
3) Wash it with distilled water, and again blow with Fields Stain B (S009) for 2-3 seconds and wash with distilled water.
4) Dry it and observe under microscope.

Principle And Interpretation

Field Stains contain methylene blue and eosin. These basic and acidic dyes induce multiple colours when applied to cells. The
fixative, methanol does not allow any futher change in slide. The basic component of white cells (cytoplasm) is stained by
acidic dye and they are described as eosinophilic or acidophilic. The acidic component (nucleus with nuclei acid) takes blue
to purple shades of the basic dye and are called basophilic. The neutral component of the cells are stained by both the dyes.
This staining method is used for screening thick films of malarial parasites.

Quality Control

Appearance
Dark violet coloured solution.
Clarity
Clear without any particles.
Microscopic Examination
Blood staining is carried out where Field's Stain A is used as one of the stains and staining characteristic is observed under
microscope.
Red cells : pink
Eosinophilic granules : orange
Neutrophilic granules : lilac

Results

Nuclei : blue
Storage and Shelf Life
Store below 30°C in tightly closed container and away from bright light. Use before expiry date on label.