Dr. Ellen Hopmans

Analytical chemist Ellen Hopmans develops techniques to measure various molecules in minuscule quantities, in material from the ocean floor, for example. ‘The main group of substances I am searching for are lipids. These are fatty substances that are produced by all living organisms. For example, when an alga dies and sinks to the floor, the lipids from those cells can literally be found millions of years later. Research on fossil lipids can therefore tell us something about the organisms that lived during a certain period and thereby something about the climate in that period.’

From algae to forest fires

‘I make use of various techniques, such as liquid chromatography, to very precisely separate the substances in a mixture. I subsequently send the separated substances to a mass spectrometer with which the mass and therefore the identity of the substance can be derived. Unfortunately, that sounds far simpler than it actually is. If a fellow researcher comes with the question as to whether I can analyse a specific molecule or a mixture of molecules from certain algae in a seafloor sample, then that usually involves a lot of puzzling beforehand. The ratio of molecules or their structure can change over the course of time, as a result of which the puzzle can become far more complex.’

‘Besides lipids, which say something about organisms that lived in a certain period, we can also search for the remains of combusted carbohydrates, such as levoglucosan. With that, we can obtain indications about large-scale forest fires in the past, which in turn also tell us something about the climate.’

Big Data

‘Nowadays, instead of searching for a specific molecule, we increasingly often analyse patterns in complex mixtures of substances. We subsequently let a computer search in the list of thousands and thousands of results to discover what is interesting in that proverbial Big Data. Whereas in the past, we at least knew which needle we were searching for in a haystack, now we are searching for a needle that we do not even know about. We know that a lot of information about the climate from the past is contained in that haystack, but we now depend on the computer to discover what it looks like. The computer basically holds an enormous magnet above the haystack to help us find the needle.’