Samm, UR - The Time Has Finally Come!

After only taking about a day and a half for my sunscreen materials to get here, I was able to start my project!

My water samples in the UV Box.

Making the zinc oxide paste.

I decided that, instead of using the 1.5 gallon fish tanks, that I would use 250-mL beakers, due to a suggestion from Heather about the concentration of sunscreen to water. There was also the hurdle of how I was going to "mix" the sunscreen into the water. With the beakers, I was able to spread the sunscreen across the sides and bottom with one of my fingers. Then, I would fill the beakers with DI water (deionized water). The sunscreen coated on the sides would represent how we put sunscreen on our bodies, and the action of it slowly leeching into the water.

I ended up using only 20g of sunscreen, since I didn't account for how many grams were in the Babo Botanical sunscreen (and I only thought to order one). I think in the end though, 20g was enough. I had a heck of a time making sure that I could get as much sunscreen onto the beaker as possible, there was just so much!

The next challenge was figuring out how to spread the pure zinc oxide over the inside of the beaker. After doing some small experiments, I found out that zinc oxide makes a nice paste when mixed with water. A couple drops here, and a few more there, and I had a relatively nice, thick paste that I could spread. It was a little more difficult to spread than the pre-made sunscreen, and my finger was on fire by the time I was spreading the paste!

Control (left) and Babo sample 1 (right)
test strips.

Comparing the Babo sample 1 with
the colour chart.

In total, I have 7 beakers: 3 coated with the Babo Botanical sunscreen, 3 coated with the zinc oxide paste, and one control (DI water ONLY), filled up to 250 mL. Today I finished Day 3 of testing, and this method of using the SenSafe test strips has opened my mind to a lot of questions. On the left is a picture of my test strips side by side. The orange colour on the control means that there was <10 µg of heavy metals in the water. Now the test strip on the right is where all this gets tricky. All of my sunscreen water samples have come out with this red/purple colour.

My test strips drying before I put them into a baggy together.

The corresponding colours on the bottle of test strips are all a tan/brown colour, and because all of my tested strips are red/purple, it's been hard to determine if there is indeed 1000 µg/L of heavy metals, or if it's a smaller number and my samples will get darker as my testing goes on. Today, it looked like one of my pure zinc samples was a little darker than all the rest of them, so I'm keeping my fingers crossed that I'll start to see a difference in intensity of colour!

Tomorrow, I'm going to set up another beaker with what little of the Babo Botanical sunscreen I have left, but use a smaller amount of DI water. I was beginning to think that maybe I had too much concentration of sunscreen for the amount of water, so I'm going to do a small side experiment to see if there is any truth to my thoughts.