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richard-jack
Team TFS
Team TFS
wastewater analysis by ion chromatographyFor many years, I’ve witnessed a very confusing aspect about cation analysis by ion chromatography. In some circles, there is a myth that suppression isn’t needed. No one would consider NOT using a suppressor for anion analysis, so why then would the opposite be true for cation analysis?

According to Dr. Joachim Weiss, author of the book titled, Ion Chromatography, 2nd Edition, by Wiley press, it appears that much of the misconception concerning suppressed conductivity for cation analysis by ion chromatography is based on myth rather than real science. In an excellent overview described in White Paper, Conductivity Detection in Cation Chromatography—Advantages and Disadvantages of Suppression, (downloadable PDF) Joachim clearly covers the many limitations for non-suppressed conductivity, i.e., the measurement is indirect, results in a higher background lowering sensitivity, requires the use of low capacity columns. Myths against using a suppressor are non-linear calibration of ammonia, which is easily overcome with current technology or a simple quadratic calibration and confusion between response factor and sensitivity. Both myths are clearly explained and refuted.

Cation suppressors are readily available, and have been for many years. Even Hamish Small, considered the Father of Ion Chromatography, has proved that suppressed conductivity for cation analysis is more sensitive. For compliance monitoring, the U.S. EPA has approved ASTM D6919, Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth Cations and Ammonium i....

By the way, you might also find this publication, Analytical Methods Approved for Drinking Water Compliance Monitoring of Inorganic Contaminants and O..., (downloadable PDF) listing contaminants and the reccomended methods useful.

Hopefully, these myths about suppressed conductivity for cation analysis have been cleared up and will no longer be perpetuated by the uninformed and by vendors that lack the capability of producing a quality cation suppressor.

 

Additional Resources


Do check out our Environmental community pages which is a wonderful resource that is totally dedicated to our environmental and ion chromatography customers and features the latest on-demand webinars, videos, application notes, and more.

 

If cation analysis by ion chromatography is of interest to your laboratory, we would like to hear from your challenges and experiences.

 

Richard Jack is currently the Director of Vertical Marketing for the Environmental and Industrial markets for the Chromatography and Mass Spectrometry Division at Thermo Fisher Scientific Inc., a Scientific Advisor to the U.S. EPA Hydraulic Fracturing Research Advisory Panel, a coauthor on the U.S. EPA Method 557, and has drafted several ASTM methods. Richard facilitates development of new applications, instrumentation, column chemistries, and software that provide customers real solutions. Richard’s breadth of experience spans designing chromatography analytical instrumentation including pumps, autosamplers, and detectors. Richard received his Ph.D. in Biochemistry and Anaerobic Microbiology from Virginia Tech University in Blacksburg, VA, where he was involved in vaccine development and, later, worked as an environmental scientist in bioremediation of toxic compounds in soils. He received his Masters in Ecology from the University of Tennessee in Knoxville, TN.