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close this bookBasic Malaria Microscopy (part I and II) (WHO - OMS, 1991, 72 p.)
View the document(introduction...)
View the documentPreface
View the documentIntroduction
View the documentLearning Unit 1. Malaria, the disease
View the documentLearning Unit 2. Cleaning and storing microscope slides
View the documentLearning Unit 3. Keeping accurate records
View the documentLearning Unit 4. Blood films
View the documentLearning Unit 5. Staining blood films with Giemsa stain
View the documentLearning Unit 6. The microscope
View the documentLearning Unit 7. Examining blood films
View the documentLearning Unit 8. Examining blood films for malaria parasites
View the documentLearning Unit 9. Artefacts in blood films
View the documentLearning Unit 10. Routine examination of blood films for malaria parasites
View the documentLearning Unit 11. Life cycle of the malaria parasite
View the documentLearning Unit 12. Supervisory aspects of malaria microscopy
View the documentBack Cover

Learning Unit 2. Cleaning and storing microscope slides

Learning objectives

By the end of this Unit you should be able to:

· describe how microscope slides for blood films are correctly cleaned, wrapped and stored
· distinguish slides that are suitable for making blood films from those that are not
· demonstrate how to wash, dry, wrap and store slides for blood films.

Cleaning slides

Microscope slides are usually supplied in boxes of 50 or 72. They may be described on the box as “washed” or “pre-cleaned”, but they will still need to be properly washed, dried and wrapped. It is not possible to make good quality blood films on dirty microscope slides. Blood films made on dirty or greasy slides will wash off easily during staining. It is therefore best to discard slides that:

· have an iridescent bloom or appear white or opaque
· are not properly cleaned
· are old, with surface scratches or chipped edges.

In order to clean slides you will need:

· a large plastic basin
· gauze or cotton wool
· a good quality detergent (powder or liquid)
· 2 - 4 clean, dry, lint-free cotton cloths
· clean water.

New slides

All new slides should be washed with detergent and clean water. After being soaked for between 30 minutes and 1 hour, the slides should be rinsed under running tap water or in several changes of clean water. Each slide should be individually wiped dry and polished with the clean, dry, lint-free cloths.

Cleaned slides should be handled only by the edges to avoid finger marks or grease being deposited on the surfaces.

Used slides

Used, dirty slides should be soaked for a day or two in water containing detergent. (Warm water should be used whenever possible.) After soaking, the slides should be cleaned one by one with a small piece of gauze or cotton wool All traces of the blood film and oil (used during microscopy) should be removed from the slides.

Do not leave the slides in the detergent for too long; soaking should be for a few days only, not weeks. If slides are left in the detergent solution for long periods, the water will evaporate, leaving a deposit on exposed slides that is impossible to remove.

After cleaning, the slides should be transferred to a fresh solution of detergent and later rinsed under running water or in several changes of clean water. They should be individually dried with the clean cotton cloths as described previously.

Slides that are slightly scratched and considered unsuitable for blood films may be handed over to other sections of the laboratory service for routine use.

Wrapping cleaned slides

To wrap cleaned slides correctly you will need:

· sheets of thin, clean paper, about II cm x 15 cm in size
· empty cardboard slide boxes (of the type new slides are packed in)
· rubber bands or adhesive tape.

Cleaned slides should be wrapped with thin paper in packs of 10. Each pack can be secured with adhesive tape or a rubber band. Packs can then be placed in the cardboard slide boxes for later use or dispatch to the field.

Slides should be stored in a dry place such as a warm-air cupboard. If stored at room temperature with high humidity, the slides will stick together after a few weeks. It will then not be possible to use them unless they are rewashed and dried.