One of the more annoying tasks that I find myself having to perform at least once every few days is cleaning my glasses. I initially try wiping them with my shirt, but that only succeeds in spreading around the dirt and producing a more uniform haze. A brief puff of moist air and a quick wipe still makes it appear as though I am in London on a foggy day. I finally fetch a moist lens cleaning towelette and a clean lens wiping cloth that I use exclusively for this purpose. This does the job and I am once again able to see with optimal clarity. Lesson learned? If I had started with clean materials in the first place, I would have saved myself a lot of frustration.
Recounting this experience got me to thinking about how something similar can apply to sample analysis, and more specifically, elemental speciation. The elements within a sample can be determined using inductively coupled plasma mass spectrometry (ICP-MS), but this, by itself, will only give you the total amounts of each element. If you want to know the composition of different chemical forms of an element present within a sample, you will need to separate these prior to their arrival at the ICP-MS. Why would you even care about elemental speciation? The main reason is because differing species can have starkly contrasting chemical properties, which impacts its toxicity and even what technology is needed to remove them from contaminated solutions (see Daniel Kutscher’s blog for more on speciation).
To get the separation needed prior to the ICP-MS there are two main options: Ion Chromatography (IC) and High Performance Liquid Chromatography (HPLC). While HPLC has been used extensively as a front end chromatographic separation technique, IC has a distinct advantage. It uses polyether ether ketone (PEEK), an inert material to produce a totally metal-free flow path. Unlike with an HPLC system, you don’t have to worry about metals leaching from your IC system, which is especially critical if you plan to determine the concentration of trace metals. Analyzing samples in the presence of a background of metals is like trying to clean your glasses with a dirty cloth. You’re just not going to get the optimal resolution. With the metal-free flow path that IC provides, you get the lowest background, resulting in the best signal to noise and the lowest levels of detection.
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So the next time you’re considering doing speciation analysis, there should be little doubt that IC is the clear choice.
For more information about speciation analysis using IC-ICP-MS, visit our resource page.