Manual of basic techniques for a health laboratory - libdoc.who.int

304 Manual of basic techniques for a health laboratoryMethod for May–Grünwald and Giemsa stains1. Fix the thin film with methanol for 2–3 minutes.2. Prepare the stains as follows:● Dilute May–Grünwald stain 1 in 2 using equal volumes of stain and bufferedwater. Mix.Example: use 10ml of stain and 10ml of buffered water.● Dilute Giemsa stain 1 in 10 using one volume of stain and nine volumes ofbuffered water. Mix gently.Example: use 2ml of stain and 18ml of buffered water.Note: Prepare only enough stain for 1 day’s use, as the diluted stains do not keepwell. Prepare the Giemsa mixture slowly and carefully. Shaking causes the stainto precipitate.3. Cover the slide with diluted May–Grünwald stain for 5 minutes.4. Tip the stain off and replace with diluted Giemsa stain for 10 minutes.Important: The staining time may need to be adjusted, especially when a newbatch of stain is received or the stain has been stored for a long time.5. Wash the stain off in a stream of buffered water. Do not tip the stain off as thiswill leave a deposit of stain on the film.6. Leave clean water on the slide for 2–3 minutes to differentiate the film. The timefor differentiation will depend on the stain and the pH of the water used. The pHshould be between pH 6.8 and 7.0.7. Tip the water off and place the slide in a draining rack to dry.Method (rapid) for Field stain1. Fix the thin film with methanol for 2–3 minutes.2. Dip the slide into Field stain B (Fig. 9.72) and count up to five. Drain and washthe slide in the first container of tap water (Fig. 9.73).3. Drain and dip the slide into Field stain A and count up to 10. Drain and washthe slide well in the second container of tap water.Fig. 9.72 Staining the blood film withField stainFig. 9.73 Rinsing the slide in water