What is a successful marriage? Is it a partnership of a similar kind or the opposite that attracts? Maybe it’s to bring out the best in each other? My parents were married for 65 years. Watching them as I was growing up, I can say it’s a give-and-take partnership. For them, marriage was new. They took advice from others and learned from their mistakes. Therefore, figuring out what works and what doesn’t. Does that sound familiar?
Traditionally, high-performance liquid chromatography (HPLC) partnered with mass spectrometry (MS) is the setup in many analytical laboratories. In recent years, we have seen a new partnership with another type of liquid chromatography (LC), which is ion chromatography (IC). At first, IC appears to be an unlikely partner for MS because it uses acids and bases as an eluent to enable ion exchange, which LC would call the mobile phase. With such an aggressive eluent, this does not partner well with stainless steel. Any metal component in the flow path will corrode. However, the IC flow path is polyether ether ketone (PEEK). The MS is mainly stainless steel, so it’s the least likely partnership until we discovered the innovative technology of suppression, which suppresses the eluent and converts it to water before entering the MS. Now, Ion Chromatography-Mass Spectrometry (IC-MS) makes perfect marriage material between the two techniques for small polar ionic species. IC provides the separation of small polar species and ionic ones that lack chromophore, while the MS provides the confirmation and identification. With them hyphenated, we can achieve low parts per trillion levels depending on which MS you choose.
To most HPLC users, this may be just another form of LC, but there are a lot of differences. First, we need to take care of the quality of water used for the eluent, making sure it is fresh — especially with reagent-free ion chromatography (RFIC). You cannot leave it for long periods of time, because bacterial growth can cause backpressure through the tubing, columns, degassers, and electrolytic devices. To ensure we get the best out of the IC-MS setup, we have to devote some attention to maintaining the backpressure and the low total background. Looking after all the electrolytics will ensure they are working optimally. The lower the background noise, the better the sensitivity. Like being newlyweds, coming into IC-MS can be challenging initially, but advice from experienced users can help.