Doctor Arturo Keller

“As they accumulate over time, they could also be affecting decomposers in the soil and other organisms that are important for a healthy agricultural system. That’s concerning because we do see accumulation,” Keller says.

“With these nanoscale formulations, what happens is you have a very condensed amount of material in a very small space, and that can be brought into cells where normally that would not happen. So you could have, locally, a very high dose, and we want to make sure this is well understood when people develop these different materials.”

“The tools that we have had for the past decade were really not capable of giving us the complete picture,” Keller explains. “Using electron microscopy, for example, we can see them, but it’s difficult to count them. When you’re looking at the field of view of an electron microscope, you could miscount very easily. You also don’t get any information about their composition directly, so it’s difficult to make sure that’s the material you’re looking for.”

He notes that some laser-based technologies are able to count nanoparticles, but they only work at the parts per million level or higher.

Keller and his colleagues use the ICP-MS to determine how much nanomaterial is present in various environmental samples—down to parts per billion or even trillion. They use the LC/MS to look at the effects of nanomaterials.

“If we expose a plant to nanomaterials, for example, we can measure: How does the plant express certain metabolites: sugars, amino acids, antioxidants, carbohydrates, fatty acids, and so on? How does it change?” Keller says. “We see, because the material has the effect of oxidation, that the plant uses all these antioxidants to try to prevent that effect. Even though we don’t see a visible effect on the plant, we can detect changes early on. That way we can say, ‘Oh, this concentration is likely to begin to cause effects as the plant grows if you keep exposing it to this material.’”

In some cases, the team has discovered unexpected benefits of nanomaterials. For example, a formulation designed to ward off pests was having beneficial effects within the plant’s energy cycle—a discovery that can perhaps be exploited to increase production.

“What’s really cool about the Agilent Thought Leader Award that I received is that Agilent has been right next to us, saying, ‘Hey, guess what? We just came up with this new column that will help you do that analysis much better.’ We tried the column and were able to get a much cleaner analysis on some amino acids, for example. We shared that with Agilent and they said, ‘Wow, that’s even more impressive than we thought.’ So we wrote an application note together.”

He reports that, working with Agilent over the past few years, the software his team uses (a single-particle module within ICP-MS MassHunter) has been improving every six to eight months.

“Early on we were able to detect particles at low concentrations, but it wasn’t as accurate as we thought it could be. That got improved so we were able to measure at the low parts per billion level. Just recently the software team came back and said, ‘You can now measure several elements at once.’ We said, ‘What? That’s exciting.’ So now we’re working with new software—same instrument but just new software—and that allows us to look at 16 different elements at one time. That is really cool. Getting more information out of the same instrument.”