Sample Preparation in Ion Chromatography

Sample preparation embraces all operations that help bring samples into a form appropriate for analysis. This includes homogenization of the sample, its dissolution, preservation, and filtration. Sample preparation is a very critical step in the entire analytical procedure because each manipulation of the sample can introduce errors in the analytical workflow. Thus, the care taken in sample preparation directly affects the quality and accuracy of the analytical results. In addition, sample preparation is often difficult to automate and, therefore, the limiting factor regarding sample throughput.

Weakly contaminated aqueous samples with moderate total ionic strength, such as drinking water, can usually be injected directly into an ion chromatograph after filtration. If the sample cannot be analyzed within a short time, sterile filtration of the sample at the point of sampling is required to remove bacteria, which otherwise would alter the sample composition as ions such as nitrite, nitrate, orthophosphate, short-chain fatty acids, and ammonium cannot be preserved in any other way. However, there are numerous application examples requiring the removal of interfering matrix components from the sample, which can be done off-line or as an intermediate first step of the subsequent IC analysis (automated in-line sample preparation). Sample preparation in ion chromatography aims to avoid overloading effects by appropriately diluting the sample, removing interfering matrix components, and/or making ions that are present in very low concentrations accessible to analysis via preconcentration. Thus, sample preparation steps are multifaceted and, depending on the required sample preparation steps, associated with a widely different instrumental setup and time expenditure.

This presentation will review sample filtration and preservation, automated sample dilution, sample preconcentration and calibration based on RFIC-ESP, the type of sample pretreatment cartridges for off-line or in-line matrix elimination, and sample neutralization.

Presenter: Joachim Weiss (Technical Director, Thermo Fisher Scientific)

Dr. Joachim Weiss started his professional career in 1982 as an applications chemist at Dionex Corporation in Germany. He currently holds the position of International Technical Director for the chromatography commercial organization at Thermo Fisher Scientific. He is renowned for his exceptional knowledge in separation science and is a recognized authority on Thermo Scientific™ IC and HPLC instrumentation and applications.