Chrome alum/gelatin coating helps slide to hold the histological sections firmly, thus reducing the risk of losing histological sections while washing and treatment during staining.
Reagents and solutions:
♦ Gelatin powder (Type A, type A, 220 or 275 Bloom)
♦ Chrome alum (Chromium potassium sulfate dodecahydrate CrK(SO4)2.12H2O)
♦ MilliQ/deionized water
Equipment and disposables
♦ Magnetic stirrer with hot plate
♦ Calibrated balance
♦ Glass beaker (1L capacity)
♦ Whatman cellulose filters (optional)
Preparation of 500 ml Chrome alum-containing gelatin solution
Step 1: Warm 500 ml water in an appropriate size beaker ( 1L capacity)
♦ Fill 500 ml MilliQ/deionized water in a beaker and warm it by placing it on a hot plate (set at 50°C).
♦ Add a magnetic bar and turn the stirring on.
Warming up the water to ≈ 50°C may take 20 – 30 min.
Step 2: Weigh out 5 g of gelatin and dissolve it in 500 ml warm water.
♦ Weigh out 2.5g of gelatin. Add a small fraction of gelatin at a time to warm water and stir gently. Add more when the added amount is dispersed into water. Try to avoid the formation of a gelatin clump.
♦ Keep stirring until all the gelatin is completely dissolved. The solution will appear clear with no floating undissolved particles.
Stir gently, avoid introducing air doubles into the solution.
Step 3: Weigh out 0.25 g Chromium Potassium Sulfate and add to the gelatin solution. Stir until it dissolves completely.
Step 4 (optional): Filter the solution through a whatman cellulose filter.
The solution is ready for use. For optimal results, use a fresh solution for slide coating. The solution can also be stored at 4°C for a few days. If a stored solution is to be used, warm it to room temperature and filter it before use.