Karen Martínez-Díaz

If it weren’t for her older sister, Melissa, Karen Martínez-Díaz might never have become a chemist. And fish smugglers in the Pacific Rim would have one less thing to worry about.

An all-around good student in high school with a knack for math, Martínez-Díaz wasn’t always sure which path would be better for her, she says. Melissa, who was a chemistry major, encouraged her sister to make the same academic choice. Today, Martínez-Díaz uses her analytical chemistry skills to keep an exotic aquatic delicacy free of a lethal poison. She is a postdoctoral researcher in the Office of Regulatory Science at the Food & Drug Administration’s Center for Food Safety & Applied Nutrition (CFSAN).

A middle child from a large family living in Las Piedras, P.R., Martínez-Díaz looked up to her big sister. “I’m glad I had her” to talk to, Martínez-Díaz says. “We were pretty close.” The first generation of their family to attend college, both sisters graduated from the University of Puerto Rico (UPR), Cayey, a 4,000-student campus situated in the middle of the island.

“This is going to sound repetitive,” Martínez-Díaz jokes, but it was Melissa who told her all about the ACS Scholars Program. Melissa’s classmate had recently become an ACS Scholar and told Melissa about the program’s benefits. “Melissa figured, ‘It’s too late for me to get the scholarship, but maybe I can help my sister get it,’ ” Martínez-Díaz says.

The younger sister applied for the program and became an ACS Scholar in 1998, toward the end of her freshman year at UPR. The award, which provides up to $5,000 annually to underrepresented minority students pursuing a degree in the chemical sciences, allowed her to focus on exploring her academic interests, a luxury not all of her classmates could afford. For friends who had to work to pay college bills, “it was so hard to concentrate, to do well in classes, because they had to spend those hours working instead of studying,” Martínez-Díaz says.

In addition to financial support, the scholars program provided Martínez-Díaz with information about career paths in chemistry, not to mention a breadth of chemistry research opportunities. “We need more programs like this,” she says.

During the summer after her junior year, Martínez-Díaz worked with graduate student Lisa Muñoz at UPR and discovered her calling: analytical chemistry research. The research combined math with chemistry in a way she loved. UPR professor Raúl Castro Santiago reinforced that interest because, in his class, students “had to think about the problems, not just read a book,” Martínez-Díaz says.

After graduating from college, Martínez-Díaz spent a year at a Puerto Rico manufacturing site for the pharmaceutical company Amgen before deciding to pursue an advanced degree in chemistry. In 2003, she began graduate work at the University of Florida, Gainesville, where she joined Weihong Tan’s group. “I loved the work he was doing,” Martínez-Díaz says. “It was analytical chemistry with a biological twist.” In that spirit, for her dissertation Martínez-Díaz made nucleic acid probes that enabled real-time measurements of how genes are expressed inside cells.

Toward the end of her studies, Martínez-Díaz began looking for work at a government agency after learning about opportunities from a grad school friend. At a career fair at the 2008 Pittsburgh Conference on Analytical Chemistry & Applied Spectroscopy (Pittcon), she met recruiter and CFSAN chemist John Callahan. She didn’t get the FDA position she initially applied for, but months later, Callahan e-mailed her, offering an interview for a postdoctoral position instead. “I was pretty surprised when I got that e-mail,” she says. But she was still excited about FDA and ended up landing the job.

Martínez-Díaz graduated from the University of Florida in December 2008, completing a master’s degree in forensic sciences and a Ph.D. in analytical chemistry.

At FDA, Martínez-Díaz is still working with nucleic acid probes. But now she’s customizing them to recognize tetrodotoxin, a small-molecule neurotoxin found in puffer fish. These fish live in waters near Japan, and they’re considered a delicacy.

They’re also big business. The Japanese government certifies that its puffer fish exports are safe. However, FDA has uncovered several cases of puffer fish smuggling, and black marketeers offer no safety guarantees. Scientists can detect tetrodotoxin in a few ways, but to comb imported puffer fish for the toxin, labs need a detection method that is specific, sensitive, and rapid. Martínez-Díaz is working to develop such a method to ensure that the U.S.’s puffer fish supply is safe. When her postdoc ends later this year, she hopes to continue as a chemist at FDA.

Martínez-Díaz still talks on the phone every day with Melissa, who is a physician practicing in Texas. She thought about following her sister to medical school at one point but says chemistry was the right choice. “I wanted to be able to create new things. I wanted to be able to challenge myself,” Martínez-Díaz says. “Chemistry has the best of all worlds.”

Please contact Kathy Fleming in the ACS Development Office for more information on contributing to this important program. She can be reached at (800) 227-5558, ext. 6210, or by e-mail at k_fleming@acs.org.