Hair Analysis Lab PDF

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Hair Analysis Lab ...

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Shantel Dixon Thursday 11:30-2:45 Feb. 6, 2019 Maggie Staples

Hair Analysis Lab

Hairs are so important when trying to help solve crimes. Being able to tell if a hair collected from a crime scene is human or animal can be the biggest break between identifying a perpetrator or even a victim. There are approximately 250,000 hairs on the human body. The most common hairs found at a crime scene are from the head or the pubic area. In animal hairs under the microscope, the medulla takes up most of the hair strand. In human hair it is the exact opposite. The roots are also shaped differently. In human hair the root is bulb-shaped, while in animal hair it is spear-shaped. This lab was conducted on Thursday, January 31st. The purpose of the lab was to be able to identify different hair samples under the microscope.

Materials and Equipment This lab requires the following: 1. Compound microscope 2. Stereoscopic microscope 3. Microscopic slide 4. Microscope cover slip 5. Mounting media (Xylene) 6. Clear nail polish 7. Forceps 8. Cat, rat, dog, human and unknown hair samples.

Procedures In a group of three, the materials and equipment were both checked to avoid inaccuracies. Next, the stereoscopic microscope, a microscope slide, and nail polish (clear) were obtained. One member pulled a few strands of hair from their head, while another member put the nail polish on the microscope slide and the third member placed the hair sample in the polish and set it to the side to dry.

While the human hair was drying, a member obtained a sample of cat hair from the instructor. One person from the group got the clean microscope slide and applied the Xylene to the slide, while the other member used the forceps to place the hair in the Xylene and gently pressed the coverslip over the hair. The microscope slide was then placed on the microscope stage and examined at 10X objective, because the 40X did not work. The medulla patterns were drawn for the hair sample. This same procedure set was used to examine the rat, dog and other human hair sample. Then, the first hair sample was finished drying, it was placed on the microscope stage and examined and the medulla pattern was drawn.

To complete the lab, the group was given an unknown hair sample. The exact procedures used for the cat, the rat and the hair sample were used to figure if the unknown hair was that of a human or an animal. The following question asked was, “What type of hair is the ‘unknown’”? The group said it was that of a human based on the

observations under the microscopeData/Results

Conclusion The purpose of this lab was to identify if a given hair sample was human or animal. Previous knowledge of working a microscope played a huge role in this lab. The results were accurate for the most part, but I still feel like the pictures could have been better despite being able to identify if it was an animal or human’s hair. I learned way more about hair than I had previously known. For example, the medulla, before this lab I never knew what a medulla was, I never even knew it was a word! I think I did well with the procedures and carefully handling everything and especially the microscope and figuring out the differences. I feel like I could learn so much more to improve. There is always room for improvement, I would really consider doing this lab again, but this time without instructions so that I know that I know what I am doing....