The samples that are fed into the mass spectrometer traditionally have to be processed in such a way that they form a clear liquid in order for the machine’s ion source (which is like a lens) to read the sample. Traditional methods involve a process similar to the following: Hunt around at the crime scene for items that can be sampled, take them back to the lab to rinse with solvents, filter and prepare them until they become a beautiful clear liquid that is then pumped into the mass spectrometer, which converts it to ions that are read by the scientists, confirming or negating the presence of whatever substance they were looking for at the crime scene, such as explosives residue, blood or drugs.
In 2005, researchers started discovering ion sources that would read solid samples. While there are lots of other universities and companies working on ways to refine this process for organic materials, for applications in things like real-time medical results during surgeries or the next airport screening technique, Merideth and Evans-Nguyen are focused on ambient elemental analysis — using the mass spectrometer’s commercial ion source to read elements like zinc, copper and iron from solid or more opaque samples.
“We would love to be able to do it quickly in the lab. A lot of other people are working on a portable mass spectrometer that you’d have in your crime scene van that has a source on it that you’re using at the scene,” Evans-Nguyen said. “Oh look at this chunk of metal — and you can immediately see that it’s useful, it has explosives on it, and you package it up and take it to the lab as opposed to making your best guess.”
Merideth wants to go into law enforcement when he graduates in December. He chose forensic science because he loves learning about science. He also thought it’d be good to have another career option if things didn’t work out with law enforcement.
“It’s been really good to learn more about my field, about what's going on in forensic science, what techniques are new, where’s the money at in the field,” said Merideth, who presented his research at the American Society of Mass Spectrometry in 2017. It really helped me understand what this degree is about, and if I ever got a job in forensics, what it would entail if I wanted to go into research.”
That being said, his research experience will serve him well in criminology.