Rhodes Analytical Chemistry student makes important innovation

Samuel Chigome, a PhD student at Rhodes University, recently returned from the United States of America after presenting his innovation of an electrospun fiber based solid phase extraction device at an international conference. The work presented by Chigome was well received by researchers from various parts of the world.

In explaining what his work was all about, Chigome said, “One of the main concerns for the analysis of chemical constituents in an Analytical Chemistry laboratory is how to get the sample in a form that is suitable for accurate analysis with an analytical instrument.

“In the analysis of liquid samples, for example, biological samples like urine and plasma a common problem is the presence of unwanted substances that can interfere with the accurate determination of the chemical constituents of interest. As a result there is a wide range of sample preparation techniques that are used to pre-treat the sample before the use of an analytical instrument.”

Solid phase extraction is a common technique that is used for sample preparation. A solid phase extraction device consists of a solid material (sorbent) that is packed into a small column. Sorbent material typically consists of powder like material, which when viewed at the microscopic level, shows that the powder is actually spherical particles that have diameters of about half the thickness of a human hair.

When a liquid sample is passed through the sorbent, the unwanted substances pass through and go to waste while the chemical constituents of interest remain trapped on the sorbent. The trapped chemical constituents are then washed off the sorbent using the appropriate liquid and the clean sample is taken to an analytical instrument for analysis.

Chigome continued, “My work was driven by current interests in Analytical Chemistry research where faster, more efficient and smaller methods for sample preparation are required that would allow the handling of very small sample volumes, cut down on the use of environmentally unfriendly organic liquids, greatly reduce the overall time of analysis and facilitate automation of analytical devices.

“We realised that a way of making solid phase extraction devices smaller and more efficient would be to use a different kind of sorbent material that would allow us to use a smaller amount of sorbent but still achieve the desired results. This brought about electrospinning - a very simple technique that uses thousands of volts to draw a polymer solution into fibers.

“The technique has the ability to fabricate fibers that have a diameter that is 100 times smaller than the diameter of a human hair, which makes them very small relative to conventional spherical particles used in solid phase extraction.”

The technique of electrospinning can be linked to nature where, for example, fiber makers like spiders make silk fibers into spider webs. However, unlike electrospinning, spiders do not use thousands of volts - they rather use Mother Nature’s processes that are not yet fully understood.

The development of this device, under the guidance of Rhodes University Analytical Chemistry Professor, Nelson Torto, was well received by the Royal Society of Chemistry’s referees and editors for the Journal of Analytical Methods. They invited him to write a review article for the sister journal, The Analyst, as well as submit some eye-catching artwork for the cover of the Journal of Analytical Methods.

The picture chosen for the cover describes the new way of fabricating a solid phase extraction device using electrospun fibers. “Having a journal feature work carried out at Rhodes University, I think, is a good reflection of the quality of research and research training coming out of this remote University. This work provides a platform for venturing into a new area, I expect that from publishing this work, a network will be created with researchers worldwide thus team up to share ideas for the advancement of science,” concluded Chigome.