Experiment Name : Preparation of Haemin crystals
Principle of the experiment
Haemoglobin readily splits into globin and heme on reaction with heat and glacial acetic acid. Small amount of heme present in the plasma is sufficient for the formation of haematin hydrochloric or haemin Crystal.
In case of our blood a small amount of NaCl might be added for the proper formation of crystals during this experiment. The reaction takes place in the following 3 steps.
- Glacial acetic acid + oxyhaemoglobin = Haematin + Globin
- Glacial Acetic acid + NaCl = Sodium acetate + HCl
- Acid Haematin + HCl = Haematin Hydrochloride
Materials Required for Preparation of Haemin Crystals
- 90% Ethyl alcohol
- Sterilised needle
- Clean and grease free slide and coverslip
- Glacial acetic acid
- NaCl
- Spirit lamp
- Microscope
- Blade or scalpels
Procedure
- At first fingertips were washed properly and sterilized by 90% alcohol and allowed to dry properly.
- At the second step the fingertip is pricked by a sterilized needle and a drop of blood is taken on the glass slide.
- The blood is spread all over the slide with the help of another slide to make thick blood film.
- It is then dried in the air or over the flame of a spirit lamp.
- The dried film is then scraped by a scalpel and collected in the centre of the slide.
- It is mounted on fresh glacial acetic acid and two crystal NaCl.
- Then the prepared sample is observed gently under the compound microscope.
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Observation
When the prepared Haemin Crystal slide is observed under compound microscope, minute dark brown, rhomboidal crystals are seen. They are arranged in the clusters. These are the Haemin crystals (more precisely Haemain hydrochloride crystals) that are formed due to reaction of heme with HCl.
Conclusion
These were the steps for preparation of Haemin crystals practical experiment in laboratory. This experiment is important in medico-legal tests for detection of blood of different species. Some important precautions are necessary in this laboratory experiment such as, using the needle carefully and properly sanitizing fingertips before and after the blood taking process.