Concluding thoughts on summer research of auto paints

Step four of my summer research plan is to conclude what I’ve learned over the summer and plan for the coming semester. I’ve learned a lot this summer about car paints and what research in a chemistry lab is all about. I learned that auto paints are way more complicated then they appear and that auto paints have evolved just as cars have evolved over time. During the last couple weeks, I discovered through some literature review a test for a base knowledge of what auto paint is made up of. This test also proved to be a helpful extraction agent and gave some distinctive spectra when paired with SERS. When I head back to the lab next semester I will further explore this method of extraction and see if I can truly identify and reproduce the characteristic spectra for the manufacturer auto paints. Once I have finished developing the method for the manufacturer paints, I will finally move on to paint samples straight from a car. I can’t wait to get back into the lab and continue exploring new ideas and developing experimental methods.

Musings on Thomas Edison and Auto Paint Analysis

Step three of my summer research plan is to identify a characteristic spectrum for each manufacturer auto paint sample. We have two different auto paints samples one from Honda and the other from Toyota. To begin the initial testing I performed a normal Raman scan without silver nanoparticles of each paint. One was found to be normal Raman active and the other was not. Normal Raman active means that without silver nanoparticles I was able to identify a characteristic spectrum. After the normal Raman scans, I performed a simple SERS test on each paint. A simple SERS test is done by only applying silver nanoparticles to the paint sample. This yielded some results but not as distinctive of a characteristic spectrum as I would like. In order to get a more characteristic spectrum, I started to develop an extraction method. The extraction method, in theory, would coax out the chromophore or pigment into the solvent making it easier to see a characteristic spectrum with SERS. However, this has not been the case. Auto paint matrixes are extremely complex with multiple additives, binders, resin, and pigments. Due to their complexity I have not been able to fully extract the chromophore, but I have been able to slowly breaking down the matrix with some simple solvents. This has allowed me to see some characteristic spectrum for the two paints, but again not to the distinctiveness that we would like. Research is a complicated process. I often like to take comfort in Thomas Edison’s wise words that he said when he was inventing the light bulb: “I have not failed. I’ve just found 10,000 ways that won’t work.” I have not failed either. I’ve just found five ways that won’t extract a paint pigment.

Reproducibility of known Auto Paints

Step two for my research over the summer is reproducibility of known auto paints from a collision center. These are not actual auto paints samples from the manufacturer but paints used by the collision center to match the manufactured paint. Over the past semester, we had identified a specific Raman spectrum using surface-enhanced Raman spectroscopy for a particular paint. My goal was to simply reproduce this spectrum. Reproducing something is often much harder then it sounds unfortunately. After much trial and error, I was able to reproduce the spectrum on multiple samples on different days. Success! I was also able to reproduce the spectrum of the other paints provided by the collision center. Through the reproduced spectra, I was also able to prove that the chromophore or pigment used by the specific collision center was the same for all the paints. Double-success! Step three is to obtain an identifiable spectrum from auto paints actually from the manufacturer.

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Have you ever watched colloids dry?

At the beginning of the summer I developed a series of steps that I need to complete in order to have a successful summer researching auto paints. The first step was stabilizing the colloidal silver nanoparticles that my lab uses; we call them colloids for simplicity. Colloids are a suspension of silver nanoparticles in a sodium citrate and water solution. Stable colloids can be applied to auto paint samples, amongst other substances, for surface-enhanced Raman spectroscopy analysis. The trick is getting them to remain stabilized. Over the past semester, our colloids were only stable for a max of two days. The lifespan of colloids should be upwards of two weeks. After reviewing the procedure that we had been using all semester, we found some flaws. We discovered that our sodium citrate was expired by three years and that we were not boiling the silver nitrate enough before adding the sodium citrate. We corrected these two details and now we have colloids that last for three weeks! With stabilized colloids, I am able to move on to step two, reproducibility of auto paint standards.

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Application of Surface-Enhanced Raman Spectroscopy to Forensic Auto Paint Analysis

Hello everyone! Have you ever been in a situation where your car was involved in a hit and run accident? Usually when this happens a paint sample is left behind by the car that hit you. This paint sample can be used in forensic analysis to identify the car of the offender. My research over the summer will be in applying a new analytical method in order to solve this common crime amongst other crimes involving paint evidence.

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