Yesterday, we had a blood identification practical, in which we were given 6 substances to test. The substances provided were chili sauce, tomato sauce, fruit juice, dyes and real blood. The tests we used were 1. the hydrogen peroxide test, 2. the luminol test and 3. the kastle-meyer reagent test.
These are the 6 substances, labeled 1, 2, 3, 4, 5 and 6. Actually, just by the appearance of the substances, we are able to eliminate some as possible blood samples. Sample 1 is actually very pink and looks like a dye, Sample 2 smells like tomato juice, Sample 3 is tinged orange, like some kind of syrup, Sample 4...looks like blood, Sample 5 looks like a purple dye and Sample 6 is quite diluted and particles are suspended in the liquid, much like watermelon juice.
After adding the hydrogen peroxide. I forgot to take a before, oops. The picture isn't very clear but Samples 4, 5 and 6 are bubbling at different degrees, and as such test positive for catalase. Sample 4 is the most bubbly followed by 5 and 6.
This is sample 4. After adding the hydrogen peroxide, it resembled foam.
This is Sample 5. It foamed for a short while and then became like this. It was purple before and became brown after adding hydrogen peroxide.
This is substance 6. It did not react until about 5 minutes later, when bubbles appeared within the liquid.
This is Janelle and Biqing's hydrogen peroxide test. They were experimenting with mixing two samples together and adding a large amount of hydrogen peroxide.
This actually looks good enough to eat, which is a little disturbing when you know that it might be blood (this is Samples 4 and 6 combined, if I'm not wrong.)
After adding Kastle-Meyer Reagent. Sample 4 is on the right, Sample 5 left.
It is observed that the centre of Sample 4 turns pink.
After adding the luminol. The luminol test narrowed down the possible samples of blood to Samples 4 & 6.
These are the 6 substances, labeled 1, 2, 3, 4, 5 and 6. Actually, just by the appearance of the substances, we are able to eliminate some as possible blood samples. Sample 1 is actually very pink and looks like a dye, Sample 2 smells like tomato juice, Sample 3 is tinged orange, like some kind of syrup, Sample 4...looks like blood, Sample 5 looks like a purple dye and Sample 6 is quite diluted and particles are suspended in the liquid, much like watermelon juice.
After adding the hydrogen peroxide. I forgot to take a before, oops. The picture isn't very clear but Samples 4, 5 and 6 are bubbling at different degrees, and as such test positive for catalase. Sample 4 is the most bubbly followed by 5 and 6. 
This is substance 6. It did not react until about 5 minutes later, when bubbles appeared within the liquid.
This actually looks good enough to eat, which is a little disturbing when you know that it might be blood (this is Samples 4 and 6 combined, if I'm not wrong.)
