Ion chromatography pioneer wins 2017 Talanta Medal

Interview with Prof. Purnendu (Sandy) K. Dasgupta

The technology that can be used to measure airborne toxins, trace nutrients and molecules in breath that indicate disease has had a significant impact on a range of fields, from environmental science to medicine. This year, the 2017 Talanta Medal has been awarded to Professor Purnendu (Sandy) K. Dasgupta, who pioneered developments in ion chromatography and related techniques.

“The news of the Talanta Medal was overwhelming,” he commented. “I have received a few awards before but to be included on the short list of the extraordinary people who have received the Talanta medal thus far is a true privilege. All of these people have been extraordinary teacher-researchers and have contributed to one or milestones in their fields. Upon being told that I have been selected by the Talanta Editors for this recognition: I could hardly speak for a while.”

A grounding in practical electronics

Prof. Dasgupta is the Hamish Small Chair in Ion Analysis and Jenkins Garrett Professor of Chemistry and Biochemistry at the University of Texas Arlington in the US. With more than 400 scientific publications and a major reference work under his belt, Prof. Dasgupta is a major player in analytical chemistry, but early on his career took some interesting turns.

After completing his Masters and some electrochemistry research in India, he moved to the US to continue his work. While developing methods related to atmospheric chemistry, he realised he needed more of a practical grounding in electronics.

“I took a home-study course to be a TV mechanic. I was the proud owner of a 25-inch TV – the largest you could get in the early 1970s. I had made it myself as part of the course, so it was truly in its glory for everyone to examine the innards, as I could not afford the cabinet. Although I did not much do electrochemistry in the classical sense, the love for solving chemical analysis problems with inexpensive instrumentation always stayed with me.”

That practical grounding and passion for instruments gave Prof. Dasgupta the skills he needed to experiment with equipment and methods – something he has seen change over the years by watching his students.

“It became more difficult to fiddle with the electronic fuel injection in automobiles that replaced carburetors, and the whole generation of American kids who acquired their mechanical skills doctoring carburetors on old jalopies to soup them up disappeared. The replacement – assembling computers out of boards – was a far less wholesome affair; unfortunately, making computer chips is not a feasible home hobby. Interestingly, electromechanical skills are now returning in actual utility of programming in robotics, in drones and so on.”

Developing pioneering techniques

It also gave him the foundation for what would become a notably productive career. After a PhD on the chemical characterization of air pollution at the California Primate Research Center, he became interested in inhalation toxicology.

“This was invaluable experience for me, giving me first direct exposure to clinical research and the lessons survive until today,” he recalled. “It also allowed me to work in close quarters with some world class people who were at the top of their game. The project that I was primarily hired for was supported by a generous grant from the private non-profit Electric Power Research Institute; this allowed the purchase of a then very new instrument, The Dionex Model 10 ion chromatograph. I am fortunate that this early instrument was easy to take apart and modify, I am sure that my initial interest and foray into the world of ion chromatography (IC) would have been stymied with today’s heavily digital instruments where parts are designed to interlock with each other.”

He spent many years working to develop IC instrumentation for atmospheric measurements where IC was part of an arrangement that simultaneously measured ionogenic gases and particles. Prof. Dasgupta’s interest extended towards flow injection analysis and the flurometric techniques he and his colleagues developed over the years for gas and solution/aerosol phase hydrogen peroxide, formaldehyde and ammonia have been used by many and improved upon by others. While the citations and recognition were welcome, they weren’t the main point for Prof. Dasgupta.

“I wish I had a fraction of the physical energy spent in an 18-hour day of hard work on the field measurements back then,” he pondered. “Flow analysis and its derivatives has consistently been a problem-solving tool for me and I have also had a great deal of fun with it when we pioneered extraction in a single drop, resulting in my most cited paper. But it’s not all about citations – I have had an equal amount of fun in working out how you can measure atmospheric gases using a soap bubble as a collector and in-situ measurement, and using a chiral selector doped soap bubble film as a membrane to separate two chiral isomers, which have not been widely used.”

Along the way, applying different techniques to answer questions led to some major discoveries. “I stumbled upon looking for environmental perchlorate initially to help a former student because he was finding it such an analytical challenge. Then finding perchlorate everywhere, especially its universal appearance in mother’s milk, became a major story. I became more interested on its effect on iodine nutrition and on iodine nutrition in general. I have since become an ‘iodine activist’ – I am convinced that iodine nutrition really needs to be improved.”

It’s applications like these that drive a large part of Prof. Dasgupta’s work; the key perchlorate and iodine papers his group worked on had a significant impact. “Analytical chemistry is a utilitarian science,” he commented. “At least half of my work has always been application driven. I do not think of myself as a chromatographer or a spectroscopist, or for that matter, a specialist in anything. I try to provide the best measurement solution to a problem with tools I am familiar with.”

One area in which Prof. Dasgupta is most recognized for his impact is developing and patenting electrodialytic devices – something that began in the mid-80s, when he was trying to improve ion chromatography. “Membrane suppressors led to electrodialytic suppressors, which led to electrodialytic eluent generators,” he explained. “The adoption of these electrodialytic techniques and the development of other related electrodialytic devices by scientists at Dionex have forever changed ion chromatography – mainstream IC today is difficult to imagine without electrodialysis.

“More recently we have been trying to take IC to the open tubular capillary format, which promises very lightweight, very low-cost instrumentation without sacrificing (likely even enhancing) current benchtop IC performance. Several new things have been developed and patented and published this decade but not yet commercialized. Much of the development of this technology was sponsored by NASA – perhaps in my lifetime I will see it used in making discoveries. Or at least on this planet, its small footprint and low cost will bring new discoveries.”

Preparing the next generation

Prof. Dasgupta’s research is now focusing on developing flow measurement techniques that ranges from implanted flow sensors to measure flow in hydrocephalic shunts to sensors that can measure sub-nL/min flow rates. He and his group are also exploring ways to perform sensitive absorbance detection in small capillaries. And more and more of his own work is becoming mathematical and theoretical.

“As I get older, I am no longer as good in the lab with my own hands,” he explained. But he is always busy passing on his skills and expertise. As a third-generation educator, teaching has always been a hugely important and enjoyable part of Prof. Dasgupta’s work, although he admits he could take or leave exam grading.

“There is an overwhelming tendency when we start to teach is to teach the way we were taught, but knowledge evolves continuously, as do means of acquiring and disseminating it,” he said. “Much as rote memorization, beginning even with multiplication tables, is not of great value, it makes no sense to test people on what or how much they can memorize. Today you need to teach how to analyze information and critically evaluate it towards decision making.

Where might his students be exploring in the future of analytical chemistry? Prof. Dasgupta sees the field developing fast in two main areas: biology and space. “The interface with analytical chemistry in these areas are no different. Analytical chemistry and analytical chemists are bound to play key roles in disease diagnostics, bedside care and treatment and making extraterrestrial discoveries.”

As ever, the field will provide researchers with challenges at every turn. Prof. Dasgupta’s advice to those doing research is to remember the past: “There have been very smart people before you – the giants are ready with their shoulders for you to stand on. The best researchers I have seen always look carefully at past work, not just in your own narrow area but in general, and always find lessons in them. As technology evolves, there is always attractive adoption of old wine in a new bottle leading to altogether new solutions.”