Sulfy: a new GC for analyzing sulphur compounds

Published on
June 11, 2019

A state-of-the-art gas chromatograph, with autosampler
and photodetector, is the brand-new addition to ETE’s already impressive
collection of analytical machinery. Sulfy, as the machine is called by its users, is specialized in measuring sulphur compounds like mercaptans and hydrogen sulphide (H2S). ‘With this machine we can analyze a wide range of sulphur compounds more accurately’, PhD scientist Margo Elzinga says.

Mercaptans, for example methanethiol (CH3SH), are organic sulphur compounds, that are present in, among others, natural gas. Burning these smelly substances results in sulphur dioxide (SO2), an important air pollutant and one of the causes of acid rain. Therefore, mercaptans have to be removed before the gas can be used. One known method is to ‘wash’ the gas by bubbling it through a highly alkalic fluid: the mercaptans will stay in the fluid, where after they can be further treated. In the past, one of ETE’s research projects was aimed at degrading mercaptans using anaerobic fermentation in a so-called UASB reactor. This resulted in the formation of hydrogen sulphide (H2S). This smelly substance can theoretically be converted into commercially valuable sulphur particles. ‘But this UASB method was very slow and the microorganisms could not deal with the higher mercaptans’, Elzinga says. ’Therefore, together with company Paqell, ETE is now focusing on a more efficient method to degrade these compounds.’

More accurate measurements

For a proper development and understanding of such a degrading process, the scientists need to measure not only the H2S formed, but also other sulphur compound that can possibly be formed during these reactions. Elzinga: ‘We need more accurate measurements of a wide range of sulphur compounds. Not only the mercaptans should be measured, but also the in-between products as well as the end products. This way, we can make an accurate balance about which compounds go where and eventually get a thorough understanding of the whole breakdown

Special coating

Assistant researcher Julian Zamudio is an expert on the new GC and his appreciation for the new lab addition is more than clear. He points to a stainless-steel tube-shaped part of the machine. ‘Here the liquid sample, containing the sulphur compounds we want to measure, is heated up and the resulting gas is led into the machine’, he explains enthusiastically. ‘Every part of the machine, that comes in contact with this gas has a special coating to prevent any interaction with the sulphur components. This way, all different compounds present remain intact and unchanged.’ The coming months Elzinga and Zamudio will work on developing their new method to degrade mercaptans and thanks to Sulfy, they hope to get a full understanding of the whole process involved.