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The Role of Ion Chromatography in Environmental Sciences

Ion chromatography can help isolate the identity of analytes with high precision

Andy Tay, PhD

Ion chromatography is a powerful technique that separates ions and charged molecules based on their affinity to the ion exchanger. Compared to methods like titration and colorimetry, it can identify and quantify analytes with greater sensitivity and reproducibility. Because of these advantages, it is routinely used in clinical diagnostics, drug development, and battery manufacturing to maintain high product consistency. Besides these industries, ion chromatography is also a useful method for environmental applications such as air and water analysis to ensure that public health and welfare are protected. 

Wastewater analysis

Wastewater monitoring is an important aspect of environmental sciences, and the industry is subject to laws and policies to meet stringent regulations before discharging wastewater. Anions and cations in wastewater can be analyzed with traditional methods including titration, photometry, and colorimetry techniques, but these methods suffer from non-specificity and limited accuracy, particularly for analytes of low concentration in wastewater. They can also be labor intensive and hard to automate. Ion chromatography, on the other hand, offers higher accuracy, precision, and throughput. 

Ion chromatography has been used to monitor nutrient enrichment in wastewater discharge to minimize undesirable ecological impact. Anionic species like nitrate and cationic species like ammonium in wastewater can cause water pollution, including river eutrophication and drop in water quality. Ion chromatography has been used to detect these analytes with high sensitivity and broad detection range. The amount of radioactivity in wastewater is also an important parameter to monitor for ecological safety and food safety. Ion chromatography has been successfully employed to provide early indication of discharge of hazardous, radioactive materials in wastewater.

Air pollution

Air quality is a major determinant of health. Ion chromatography allows scientists to isolate air pollutants, like carbon monoxide and lead, and quantify their levels so they can provide warning should the levels exceed safety limits. Another application is to analyze the levels of particulate matter 10 micrometers (PM10) emissions from diesel engines and industrial factories, which has been implicated in respiratory illnesses. What makes ion chromatography a much more useful method than other detection techniques is that it can detect for multiple cationic and anionic species. Researchers from Tsinghua University, China, made use of ion chromatography to simultaneously identify 12 water-soluble inorganic anions and 15 water-soluble organic ions in atmospheric aerosols. 

Oil spills

All crude oil contains trace metals such as nickel and vanadium, even at different metal ratios. When oil spills happen, ion chromatography coupled with mass spectrometry may be used to detect for these metals and their ratios can be analyzed to identify the source of spills. When oil spills are large, these trace metals could also adversely affect the environment. Ion chromatography can be used to determine the extent and spread of the spill, characterize the environmental impact, and assess the effectiveness of solutions to contain and clean the spills.

Overall, ion chromatography is a much more sensitive and reproducible method compared to titration and colorimetry to identify and quantify analytes. This allows companies and regulators to better analyze environmental hazards, monitor business activities that could impact the environment and protect public health, and to take actions in a timely manner.