MORPHOLOGICAL AND TINKTORIAL PROPERTIES OF BACTERIA - E. L. Zaitseva - 2015

CHAPTER II. DEGREASING OF SLIDES

Purpose: to ensure proper adhesion and even distribution of the test specimen on the Glass slide.

The accuracy of Cell/15.html">Microscopy largely depends on the quality of smear preparation. Microscope slides and coverslips used for preparing specimens require special preparation. Slides should measure 26x76 mm and be no more than 1.1–1.4 mm thick, while coverslips should be 0.15–0.17 mm thick—requirements dictated by the Optical Properties of the Abbe condenser. They must also be clean and thoroughly degreased. This can be achieved in various ways.

Methods for slide degreasing:

1. New slides are boiled for 15 minutes in a 1% sodium carbonate solution (or soapy Water), then rinsed with water, placed in a weak Hydrochloric acid solution, and thoroughly rinsed with water again.

2. Used slides are first placed in concentrated sulfuric acid or in a mixture of 100 parts sulfuric acid, 50 parts potassium dichromate, and 1000 parts water for 2 hours, after which they are boiled in an alkali solution and thoroughly rinsed with water.

3. Slides are immersed in a mixture of 6% potassium chromate and sulfuric acid for 24 hours, followed by a thorough water rinse. The slides are stored in a 96% alcohol solution.

4. Slides can also be treated with a cleaning fluid of the following composition (according to Zettnow, 1899): Kalii bichromici – 20 g, Acidi sulfurgi crudi – 20 g, water – 200.0 ml. After boiling in this mixture for 10 minutes, the slide is rinsed for 5 minutes in a weak alkali solution, then in water, and finally in alcohol.

Before use, slides are rubbed with a piece of dry soap and then thoroughly polished with gauze until they shine.

For long-term storage, clean, degreased slides are placed in glass jars with ground-glass stoppers containing Nikiforov's mixture (equal volumes of 96% ethanol and sulfuric ether), kept in 96% alcohol, or stored washed and wiped dry.

Evaluation of results. On a clean slide, a drop of tap water or isotonic sodium chloride (NaCl) solution spreads freely across the entire surface, whereas on a greasy slide, it breaks up into numerous tiny droplets.