Ion chromatography, a technique for separating ions in a sample by passing it through a column, has traditionally been confined to laboratories due to its reliance on expensive, complex machinery. However, a team of scientists at the University of Tasmania in Australia has pioneered a simplified, portable approach, making this advanced analytical method accessible for fieldwork and, more importantly, for modern science classrooms.
In a collaborative effort, these scientists engaged second-year undergraduate students in analyzing soil pore water—the water found between soil particles—directly at the collection site. Utilizing their newly developed portable ion chromatograph, Aquamonitrix, students were able to instantly separate and measure concentrations of nitrate and nitrite ions, both of which are environmental concerns in high amounts. For comparison, the samples were also brought back to the laboratory for analysis with a conventional chromatograph.
The results of their study, documented in the Journal of Chemical Education, confirmed the effectiveness of the portable device. It yielded measurements for nitrate and nitrite ions that were highly comparable to those obtained from the more complex laboratory-based equipment.
Chemistry Beyond the Benchtop
Professor Brett Paull, a leading chemistry professor at the University of Tasmania and the study’s senior author, emphasized their goal: “We are always keen on moving our chemistry out of the traditional laboratory setting and into the field. This ensures students grasp that analytical chemistry isn’t just an in-lab exercise, but a versatile skill applicable in any environment.”
The 2023 ACS Guidelines for Undergraduate Chemistry Programs highlight the importance of hands-on experience in separation techniques like chromatography within undergraduate curricula. Although traditional lab equipment provides valuable experimental practice, it often falls short in preparing students to apply their analytical expertise to practical, real-world situations.
To address this, Professor Paull and his team partnered with Aquamonitrix, the manufacturer of the portable ion chromatograph, to enable undergraduate students to conduct real-time sample analysis directly in the field.
“Portable instruments empower us to venture outside the lab and perform direct, immediate measurements right where they’re needed,” Dr. Paull stated.
Designed for Simplicity and Efficiency
The experimental process began with students extracting soil pore water using a portable vacuum pump. This water was then filtered on-site and immediately injected into the Aquamonitrix chromatograph.
Aquamonitrix operates as a straightforward, low-pressure ion chromatograph, expertly separating anions using a relatively compact column. Crucially, the solution that transports the sample and aids anion exchange within the column uses only sodium chloride, making the entire analytical process remarkably environmentally friendly.
For precise detection of nitrate and nitrite ions amidst other anions, the device incorporates an affordable absorbance detector that utilizes UV light. Since both nitrate and nitrite readily absorb UV light, students could observe distinct peaks on the chromatogram, clearly indicating the presence of these two specific anions.
“Nitrite and nitrate show excellent absorption in the low UV spectrum, and we encounter virtually no interference from other anions,” Dr. Paull elaborated. “This inherent simplicity is a major advantage, as it prevents the messy chromatograms often seen with complex samples.”
Specialized Simplicity
Upon returning to the lab, students compared their field measurements with those from a standard commercial ion chromatograph. The results were remarkably consistent, demonstrating that the portable device delivers accurate data with significant savings in both cost and time.
Dr. Paull highlighted that traditional lab-based ion chromatographs are “far more intricate, costly, and advanced,” typically employing longer columns and high-pressure pumps. While powerful, they often detect a broader range of anions, leading to more complex chromatograms that can be harder to interpret.
“Our goal isn’t to do everything,” he clarified. “It’s simply impractical to bring a $100,000 laboratory instrument into a greenhouse for on-site use. Instead, we focused on creating a $10,000 device that excels at one or two specific tasks, is battery-operated, and can be easily used by students without extensive prior training. We are not attempting to replicate the entire lab in the field, but rather to develop affordable, adaptable instruments suitable for practical outdoor analysis.”
Building on this success, the scientists are also developing a complementary instrument capable of measuring ammonia levels directly in the field.
“With nitrite, nitrate, and ammonia measurements, we can eventually analyze the complete nitrogen cycle, for instance, in water treatment facilities or within soil chemistry,” Dr. Paull explained.
Furthermore, the team is actively developing a similar portable device designed to detect arsenic in contaminated soils and agricultural regions. The presence of this toxic element in soil poses a significant environmental and health risk, especially in areas like India and Bangladesh, which rely heavily on groundwater extraction.
Enriching the Learning Experience
Dr. Vipul Gupta, a chemistry lecturer at Deakin University in Victoria, Australia, highlighted the profound educational impact: “By empowering students to conduct both field and laboratory analyses, this portable device offers a holistic learning experience, seamlessly blending theoretical concepts with practical application. The hands-on nature of these experiments, combined with the chance to tackle genuine environmental issues, significantly sparks curiosity and deepens interest in analytical chemistry.”
Dr. Gupta also believes this methodology can be expanded to facilitate continuous, long-term environmental monitoring directly in the field.
“Beyond that,” he added, “I anticipate that exposure to such portable systems will inspire future students to conceive and develop their own innovative analytical chemistry projects.”
Dr. Paull concluded, “It’s often challenging to ignite students’ enthusiasm for analytical chemistry if their learning is strictly confined to the lab. When you take them into the real world, demonstrating how analytical measurements are performed in an actual environmental setting, the experience becomes far more engaging and enjoyable for them.”
“And they truly learn a lot more.”
This article was written by Rohini Subrahmanyam.