Answering a burning question
Polycyclic Aromatic Hydrocarbons (PAHs) are everywhere. Occurring naturally in coal, crude oil, and gasoline, they are also produced when fossil fuels, wood, and garbage are burned. Commercially produced PAHs are used to make everything from mothballs to organic light-emitting diode (OLED) TV monitors.
PAHs are also a major source of air pollution and linked to adverse health impacts, including the development of certain cancers and low birth weight and neural tube defects in babies. The Agency for Toxic Substances and Disease Registry has identified 17 PAHs (among hundreds) as being of greatest concern with regard to potential exposure and adverse health effects on humans.
Despite the ubiquity and toxicity of PAHs, relatively little is known about them at the molecular level. However, that situation is now changing, thanks to the efforts of Prof. Sunghwan Kim of South Korea's Kyungpook National University.
"My work is dedicated to understanding polyaromatic hydrocarbon compounds -- identifying what kinds of PAH compounds exist in the nature and trying to understand their chemistry," said Prof. Kim. "To achieve that goal, I use mass spectrometry, ion mobility mass spectrometry, UPLC, HPLC, and gas chromatography as major tools."
"If we understand nature, maybe we can fix the environmental problems we have caused to nature."
From toxicity to TVs
Those tools are enabling Kim's research, opening new doors of discovery.
"It's well known that PAHs are bad for humans and animals, but studies of their harmful effects have been limited to just a few PAH compounds due to limitations of analytical techniques," said Kim. "With the advancements in technology in mass spectrometry and chromatography, we are now able to detect more compounds and analyze them, both quantitatively and qualitatively, so that we can begin to understand their origin and chemistry."
Kim's work is wide ranging. He's working with toxicology experts to study PAHs in nature and their effects at the cellular level. In his research, he has demonstrated how PAH compounds oxidized by UV light can have a toxic effect on cells in the laboratory. He's hoping to expand that research in the next several years to studying the impact of PAHs on marine life, specifically fish.
On the other end of the spectrum, Kim is working with TV manufacturers LG Electronics and Samsung.
"The basic structure of compounds used for OLED TV monitors is made up of PAHs," noted Kim. "The manufacturers are trying to develop analytical methods by which they can understand the oxidation of those PAH compounds and how that degradation affects the monitors' performance. Again, mass spectrometry and chromatography are very important, because some of the compounds, especially the degradation or oxidation products, exist in very, very small quantities."
"Today, the EPA regulates a number of PAH compounds. We believe that there are more PAH compounds that should be watched. We're working to expand that list."
Many of Kim's analytical experiments are breaking new ground in the field. A search on ResearchGate.net reveals his name as co-author on 82 articles in publications such as Analytical Chemistry and Journal of Chromatography. In what is considered to be a scientific first, he and his team recently published a paper in the Journal of Chromatography demonstrating how a mobile phase of deuterated methanol and supercritical CO2 for Waters ACQUITY UPC2 system coupled to a Waters mass spectrometer with atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI), could separate, and thus speciate, thirty one nitrogen - and/or oxygen-containing standard compounds in 20 minutes. This experiment allows one to identify the functional groups attached to PAH compounds which is important for understanding their chemical structure.
A scientist from the start
That pioneering spirit has driven Sunghwan Kim since he was a child in Seoul.
"From when I was young, in middle school, I wanted to be a scientist," Kim recalled. "And I wanted to understand nature. I don't know where I got the idea, but that's what I wanted to do."
That interest led him to earning a bachelor's degree at Seoul National University in Korea before traveling to Oregon State University in 1997 to work on his Ph.D in analytical chemistry. By then, Kim was married and when his wife got a job at Ohio State University, he transferred there and finished his doctorate in 2003. He also found a mentor.
"I was very impressed by Prof. Patrick G. Hatcher," remembered Kim. "He's a person who always tried to do new things, and supported me in doing new things."
After post-doctoral work at Florida State University, Kim returned to South Korea as a senior researcher at the Korea Basic Science Institute before moving to Kyungpook National University in 2009. The idea of doing new things continues to inspire him.
The satisfaction of finding new answers
"I published a paper in 2014 on how we can use information obtained from ion mobility mass spectrometry to identify the structure of PAH compounds," cited Kim as an example of what motivates him. "It took almost three years to complete. One day, I just came up with an idea by which we can combine the data for ion mobility, theoretical calculations of collision cross section (CCS) values, and high resolution mass spectrometry data. By combining those three data, I realized that we could get new information to develop a fuller understanding of those chemistries. I was very satisfied at that moment."
When he isn't in the laboratory, Kim enjoys listening to classical music and watching fantasy and action movies. He's also arguably South Korea's biggest fan of American college football.
"I attended a couple of Buckeyes games when I was at Ohio State -- the year they won the national championship -- and it was just a great experience that I’ll never forget," explained Kim.
"Right now, I have two goals," said Kim. "First, I want to know about Mother Nature -- to understand the PAH compounds that are generated in nature, so that we can live in harmony with nature. My second goal is to teach young people to achieve their goals in their careers. Education is a very, very important part of the research that I'm doing now."
