Standard 3% hydrogen peroxide found at the store works fine. Always wear gloves when handling any solutions you believe to be biological, such as blood.
Setup a positive and negative control to make sure the experiment is working. A positive control tells you that your experiment is working while a negative control makes sure that you aren’t getting results that are false positives. Test a substance you know contains no cells, such as paint. This is your negative control. Your positive control will be another sample that you know is blood.
If you don’t have an eyedropper, you can use a cotton swab soaked with hydrogen peroxide and rub it into the sample. Test the same sample multiple times to make sure you get the same results.
If the sample doesn’t bubble, it isn’t blood. If the sample does start to bubble, you still can’t be totally sure it is blood, but this is a good step forward in determining that it is blood.
You can use the catalase test as a first step. If it tests positive, you can move forward with more specific tests. This method is also not very good for detecting dilute concentrations or small amounts of blood.
Phenolphthalein cannot be obtained in stores and must be purchased online. It is easiest to purchase a “Kastle-Meyer Test Kit” as it will contain all of the necessary resources. The standard strength 3% hydrogen peroxide is sufficient for this test. The small eyedropper is optional, it just makes it easier to apply the solutions to the cotton swab. Always wear gloves when working with biological substances like blood.
The swab doesn’t need to be soaked, it just needs to be moist. The alcohol increases the sensitivity of the test by making the hemoglobin more exposed.
If your sample is dry or you don’t have much to work with, you can cut up the fabric into smaller pieces and test that directly. Get the piece damp with rubbing alcohol and proceed to the next step. You only need a very small piece to work with: the size of a fingertip should be sufficient.
If you are working with the cloth directly, add the phenolphthalein directly onto the cloth.
The hydrogen peroxide reacts with the phenolphthalein and any iron present in the substance. Again, drip the hydrogen peroxide directly onto the small piece of cloth.
Try testing your sample multiple times to see if you get the same result. Again, make sure you have added all of the reagents to the sample in the correct order. This could be a source of error if you are quite certain you have blood, but the test comes back negative.
This test is prone to false positives because many vegetables and some metals will also react. Further analysis of the sample is necessary once you have a positive from this test. [10] X Research source
