Webinar: Five Essentials for Ion Chromatography Applications
About the Webinar
In our recent webinar, Inorganic Ventures’ Technical Director, Mike Booth, shared his insights into Ion Chromatography (IC). Although IC isn’t a topic we talk about a lot at Inorganic Ventures, it’s a powerful technique we’ve been using for years, and Mike was excited to share some key knowledge. Below are the five essentials that Mike covered during the session.
1. Background Signal and Its Importance in IC
Mike began by discussing background signal, emphasizing that it’s mainly dependent on the eluent you use. The cleaner your eluent, the lower your background signal will be, and that’s going to help in a lot of ways, including improving detection limits. He reminded us that even if you’re using an eluent generator, you still need clean water for the system, and using dedicated lab equipment just for IC, like graduated cylinders and pipettes, can help avoid cross-contamination.
He recommended keeping a maintenance log for your system, noting when you prepare new eluents and tracking background conductivity to catch any issues early. Mike also mentioned a resource on the Inorganic Ventures website: a quick 5-minute video about making clean eluents that’s worth checking out.
2. Constructing Calibration Standards
When it comes to constructing calibration standards, Mike pointed out that most IC users prefer to prepare their standards from single-element stocks rather than blended standards. He walked through a typical Excel setup, where you track your lot numbers and calculate the final concentrations. Mike suggested preparing standards by weight instead of volume, as it’s more accurate.
For anions, stability can be tricky, especially with standards like nitrite and phosphate. Nitrite can convert to nitrate if not handled properly, but Mike recommends adjusting the pH to 10 or higher to stabilize it. Phosphate, on the other hand, is prone to biological growth. Adding a biocide can help stabilize it, and Mike noted that Inorganic Ventures offers blended standards that are demonstrated to be stable for up to five years.
3. Combating Interferences
Mike then moved into combating interferences in IC, which often comes down to co-elution. He showed an example of a sample containing fluoride, acetate, and formate, which, on one column, came out as a messy, unresolved set of peaks. To fix this, he switched to a different column and tweaked the eluent concentration, achieving much better separation, though it came at the cost of longer analysis time.
The key takeaway here is that choosing the right column and making adjustments to your eluent concentration can significantly improve your separation. However, keep in mind that there’s always a trade-off between resolution and sample throughput. Mike also reminded us that IC software measures conductivity versus time, meaning it’s up to you to validate the retention times of your peaks by running single standards.
4. Method Development: Isocratic vs. Gradient Methods
When discussing method development, Mike explained the difference between isocratic and gradient methods. An isocratic method keeps the eluent concentration constant throughout the run, which makes troubleshooting simpler. Gradient methods, on the other hand, allow you to vary the eluent concentration to separate more challenging analytes, but they are more complex and take more time.
In one of his examples, Mike showed a gradient method that was used to separate a mix of organics and inorganics, requiring a runtime of over 140 minutes. While it’s a lengthy process, the gradient allowed for the separation of a challenging set of analytes. His advice? Start with column manuals, application notes, and white papers from manufacturers when developing methods.
5. Troubleshooting: Focus on Baseline Stability
Finally, Mike covered troubleshooting, with a primary focus on baseline stability. He shared examples of unstable baselines and recommended starting with a check of the eluent concentration and pump valves if you see fluctuations. Injecting water through the system can sometimes help stabilize the baseline as well.
He also discussed issues like peak tailing, often caused by dead volume in the plumbing, and broad peaks, which can usually be fixed by diluting the sample or switching to a smaller injection loop. For issues with peak resolution, Mike advised checking your eluent preparation and potentially replacing the column if performance continues to degrade.
Conclusion: Supporting Your IC Journey
Mike wrapped up the webinar by reminding us that Inorganic Ventures is here to help. We offer stock singles and blended standards for IC, including anion and cation standards, and we also have custom standards available to meet your specific needs. If you want to save time on standard prep, reach out to our team for a custom solution.
And don’t forget about our educational resources! Check out IV Ignite, our virtual training platform, for more in-depth learning, and consider signing up for our 2024 ICP Workshop, which offers in-person training in all things ICP.
If you missed the live session, the recording is available below. Feel free to revisit the webinar or share it with colleagues who might benefit from the information.
