Cheers to IC!
Art Fitchett recounts his early days in ion chromatography and highlights how a string of innovations have made it a beverage analysis workhorse.
Art Fitchett |
sponsored by Thermo Fisher Scientific
It was while I was at the DuPont Experiment Station as an analytical chemist in the biochemicals department that I was first exposed to ion chromatography (IC). I read the first article in Analytical Chemistry with great enthusiasm and told my management how useful the technology could be in a number of different challenging areas. Their response was, “Go build one!” I ignored that remark and went to a seminar by Dionex. Having seen a system in operation, I went back to my managers with a letter of justification that included 10 specific problem areas.
In 1976, I was allowed to buy my first ion chromatograph (the first ever commercial instrument was sold in October 1975, so I was a real early adopter). I started working on my new IC system and within a week I’d solved all 10 application problems. Within another few days, I’d solved another challenge in the business and they wanted my IC system for that project, so I had to buy another. So in just a month or two, we had purchased two ICs at DuPont and I had become the unwitting IC guru. I was asked to present IC technology to other operating departments and to see how applicable it was to solving their problems, so I developed a training seminar and wrote courses on methods development.
Teaching Dionex a thing or two about IC
Dionex found about what I was doing and asked me to share what I had learned with them. I put on a three-day workshop about IC for Dionex and at the end of the month, I was invited to join the company. I started in November 1977. To cut a long story short, I was heavily involved in the creation of US Environmental Protection Agency Method 300.0 (Determination of Inorganic Anions by Ion Chromatography), which put IC into routine use – and the rest is history!
The development of hydroxide-selective anion-exchange columns was a game changer for IC and opened up a number of new markets, including food and beverages. The ability to generate high-purity eluent (in this case hydroxide) electrolytically was also key; not only did it increase sensitivity, it also allowed us to run gradient separations with an isocratic pump, which meant we could analyze both the inorganic species but also the bulk of organic acids that we find in food and beverages. Another major step for beverage analysis using IC was the introduction of pulsed amperometric detection, which facilitated the analysis of carbohydrates. More recently, the introduction of 4-µm particle size packing materials has allowed us to really ramp up separation efficiency – today’s IC peaks look like they’ve come off a GC system!
The marriage of IC and mass spectrometry is another significant but natural step forward. IC systems are now even being connected to our top-end Thermo Scientific™ Orbitrap Fusion™ Tribrid™ Mass Spectrometers, which pushes the technique into another new application area: metabolomics. Meanwhile, hyphenation with inductively coupled plasma (ICP)-MS opens the door to arsenic speciation, which is another interesting application area in food and beverage analysis.
Looking back over nearly 40 years, it’s surprising to see just how much innovation has gone into modern IC systems, such as the Thermo Scientific™ Dionex™ ICS-5000+.
From water to wine
It’s fair to say we’re working with all the major manufacturers of beverages when it comes to the application of IC. To offer just a few examples, we can start with the measurement of bromate in bottled water; IC is the only real way of conducting such an analysis, so it’s an important application that links nicely back to IC’s strong history in environmental applications.
Having the potential to analyze all the inorganics and the majority of the organic acids in a single run means that it’s easy to visualize the difference when a process goes awry, or if a beverage product has spoiled. I often share the example of fresh and spoiled orange juice; when we overlay the chromatograms, we can clearly see how peaks have changed and how new peaks have appeared through spoilage, so it can be used as a profiling tool.
Coffee manufacturers like to assess organic acids and carbohydrates in extracts to assess whether the roasting process is robust, and microbreweries might do the same to monitor the fermentation of IPAs that are popular because of their complex flavor profiles.
Sports drinks – where electrolytes, carbohydrates and amino acids may all be of interest – also lend themselves to IC analysis, which can offer a full profile in a single run.
On the cation side, we can take a look at biogenic amines, such as histamine, cadaverine and putrescine in wine. Histamine is regulated in some regions because it is considered an early indicator of decomposition (or poor winemaking) – the same can be said of other biogenic amines, and winemakers are naturally concerned about the negative sensory impact they could have on wine.
And the list goes on...
Back in the mid-1970s, all we had was ion chromatography with conductivity detection. I couldn’t have imagined all of the applications of today – and we’ve not done innovating yet. IC has given me a long, successful and varied career, so I can say in earnest, “Cheers to IC!”
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