Week Seven: A Rough Week

Hi blog, and welcome to week seven!

This week has been quite eventful. I came into the week with the plan to run two experiments: a PFOS Water MIP but with a slower scan rate and soak time of 40 minutes on Monday and Tuesday and the same thing but with HCl acid soaks on Thursday and Friday, but that plan quickly went awry.

Everything went as planned on Monday. I did the Acid MIP Fabrication (“Fab”) with the same measurements I had last week – o-PD, HCl acid, and 15 mL of PFOS in water. I created the MIP, characterized the electrode at each necessary step, saved all my files, and uploaded the information to PowerPoint; nothing went wrong. However, Tuesday afternoon is when things started going downhill, and it unfortunately remained that way for the rest of the day.

As I was in the middle of sensing, the white wire connected to the reference electrode broke. I had the exact same thing happen to me not long ago, which I wrote about in a previous blog post. The CV and DPVs I was getting were the same jagged ones I had seen a little less than a month ago. Once the wire was switched, and I made a couple tiny adjustments (i.e. flipping the direction the gold electrode was facing), things seemed to be working again. This is my second MIP that got burned, and we’re going to look more in-depth into the problem with the wires so that hopefully no one will have to face this issue anymore.

It didn’t end there, though. Because my MIP was burned, I started over with the fabrication process. Everything was ran smoothly and the Acid MIP Fabrication CV looked great (like the one pictured in my blog post last week), but right as I was about to finish the experiment and head out for the day, I observed an abnormal CV (image below) and DPV for the last step – the extraction (removing the PFAS molecules to make the “swiss cheese mold”/imprinted polymer). What I should have seen was a normal duck curve, so the CV I got suggests that my MIP was not fully extracted. Thus, I had to scrap my second attempt at the experiment, too. I feel like I’ve set a record with my two failed MIPs in one day.

 (Fiona Xu)

Long story short, I was stuck trying to conduct the same experiment for this entire week. It makes me feel better to know that the experiment going south was due to something out of my control and not because of a procedural error I made, but it was still irritating that I basically got nothing done on Tuesday :(.

I also had plans to collect a water sample from the Great Falls Park (Patowmack Canal) this week, but things didn’t fall into place. I will most likely collect it next week, as I have the supplies prepared for field sampling: gloves, plastic container, cooler, and a permanent marker. Additionally, I started drafting my final Senior Project paper.

Despite the bad luck I ran into this week, I want to also focus on the positive things that happened. On the bright side, I had no issue completing the experiment on Wednesday and Thursday. It’s also taking me less and less time to prepare the solutions needed for experiments. I feel like I’m developing the “muscle memory” of measuring out the o-PD and ferrocene methanol and pipetting the aqueous stock solutions and acid.

My coworker also shared with me a tip on how to make the sonicating step quicker: wiggle the vial to accelerate the dissolving of the solid pieces. For example, the o-PD, PFOS, and acid solution would take up to 15 minutes to sonicate at times, but now it’s consistently shortened to five minutes. The sonicator uses high frequency sound waves to break down large particles (in our case solid o-PD or ferrocene methanol) and homogenize solutions.

Vial sitting in the sonicator bath (Fiona Xu)

Hopefully I’ll be able to follow through the plans I set up next week. See you then!

Fiona